Sensors

10 pages, 3834 KiB

Open AccessArticle

Simulation of SAW Humidity Sensors Based on ( 11 2 ¯ 0 ) ZnO/R-Sapphire Structures

by Xiao-Dong Lan¹, Shu-Yi Zhang^1,*, Li Fan¹ and Yan Wang^1,2

¹ Laboratory of Modern Acoustics, Institute of Acoustics, Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing 210093, China

² College of Electronic Engineering, Nanjing University of Posts and Telecommunications, Nanjing 210046, China

Sensors 2016, 16(11), 1112; https://doi.org/10.3390/s16111112 - 2 Nov 2016

Cited by 15 | Viewed by 5778

Abstract

The characteristics of two types of surface acoustic waves SAWs (Rayleigh waves and Love waves) propagating in bilayered structures of

(11 \bar{2} 0)

ZnO/R-sapphire are simulated by a finite element method (FEM) model, in which both SAWs have crossed propagation [...] Read more.

The characteristics of two types of surface acoustic waves SAWs (Rayleigh waves and Love waves) propagating in bilayered structures of

(11 \bar{2} 0)

ZnO/R-sapphire are simulated by a finite element method (FEM) model, in which both SAWs have crossed propagation directions. Furthermore, based on the bilayered structures, the frequency responses of Rayleigh wave and Love wave humidity sensors are also simulated. Meanwhile, the frequency shifts, insertion loss changes and then the sensitivities of both humidity sensors induced by the adsorbed water layer perturbations, including the mechanical and electrical factors, are calculated numerically. Generally, the characteristics and performances of both sensors are strongly dependent on the thickness of the ZnO films. By appropriate selecting the ratio of the film thickness to SAW wavelength for each kind of the sensors, the performances of both sensors can be optimized. Full article

(This article belongs to the Section Physical Sensors)

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10 pages, 1620 KiB

Open AccessArticle

Label-Free Fluorescent Detection of Trypsin Activity Based on DNA-Stabilized Silver Nanocluster-Peptide Conjugates

by Cai-Xia Zhuo^1,2,†, Li-Hui Wang^1,2,†, Jing-Jing Feng^1,2 and Yao-Dong Zhang^1,2,*,†

¹ Key Laboratory of Applied Surface and Colloid Chemistry of Ministry of Education, School of Chemistry and Chemical Engineering, Shaanxi Normal University, Xi’an 710062, China

² Key Laboratory of Analytical Chemistry for Life Science of Shaanxi Province, School of Chemistry and Chemical Engineering, Shaanxi Normal University, Xi’an 710062, China

^† These authors contributed equally to this work.

Sensors 2016, 16(11), 1477; https://doi.org/10.3390/s16111477 - 9 Nov 2016

Cited by 19 | Viewed by 8762

Abstract

Trypsin is important during the regulation of pancreatic exocrine function. The detection of trypsin activity is currently limited because of the need for the substrate to be labeled with a fluorescent tag. A label-free fluorescent method has been developed to monitor trypsin activity. [...] Read more.

Trypsin is important during the regulation of pancreatic exocrine function. The detection of trypsin activity is currently limited because of the need for the substrate to be labeled with a fluorescent tag. A label-free fluorescent method has been developed to monitor trypsin activity. The designed peptide probe consists of six arginine molecules and a cysteine terminus and can be conjugated to DNA-stabilized silver nanoclusters (DNA-AgNCs) by Ag-S bonding to enhance fluorescence. The peptide probe can also be adsorbed to the surface of graphene oxide (GO), thus resulting in the fluorescence quenching of DNA-AgNCs-peptide conjugate because of Förster resonance energy transfer. Once trypsin had degraded the peptide probe into amino acid residues, the DNA-AgNCs were released from the surface of GO, and the enhanced fluorescence of DNA-AgNCs was restored. Trypsin can be determined with a linear range of 0.0–50.0 ng/mL with a concentration as low as 1 ng/mL. This label-free method is simple and sensitive and has been successfully used for the determination of trypsin in serum. The method can also be modified to detect other proteases. Full article

(This article belongs to the Special Issue Colorimetric and Fluorescent Sensor)

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13 pages, 1707 KiB

Open AccessArticle

Glucose Oxidase Biosensor Modeling and Predictors Optimization by Machine Learning Methods

by Felix F. Gonzalez-Navarro^1,*

, Margarita Stilianova-Stoytcheva¹, Livier Renteria-Gutierrez¹, Lluís A. Belanche-Muñoz²

, Brenda L. Flores-Rios¹ and Jorge E. Ibarra-Esquer¹

¹ Instituto de Ingeniería, Universidad Autónoma de Baja California, Mexicali, B.C. 21290, Mexico

² Computer Science Department, Universitat Politecnica de Catalunya, Barcelona 08034, Spain

Sensors 2016, 16(11), 1483; https://doi.org/10.3390/s16111483 - 26 Oct 2016

Cited by 42 | Viewed by 8606

Abstract

Biosensors are small analytical devices incorporating a biological recognition element and a physico-chemical transducer to convert a biological signal into an electrical reading. Nowadays, their technological appeal resides in their fast performance, high sensitivity and continuous measuring capabilities; however, a full understanding is [...] Read more.

Biosensors are small analytical devices incorporating a biological recognition element and a physico-chemical transducer to convert a biological signal into an electrical reading. Nowadays, their technological appeal resides in their fast performance, high sensitivity and continuous measuring capabilities; however, a full understanding is still under research. This paper aims to contribute to this growing field of biotechnology, with a focus on Glucose-Oxidase Biosensor (GOB) modeling through statistical learning methods from a regression perspective. We model the amperometric response of a GOB with dependent variables under different conditions, such as temperature, benzoquinone, pH and glucose concentrations, by means of several machine learning algorithms. Since the sensitivity of a GOB response is strongly related to these dependent variables, their interactions should be optimized to maximize the output signal, for which a genetic algorithm and simulated annealing are used. We report a model that shows a good generalization error and is consistent with the optimization. Full article

(This article belongs to the Special Issue Advances in Artificial Intelligence: Selected Papers from MICAI 2013, 2014 and 2015—12th, 13th and 14th Mexican International Conferences on Artificial Intelligence)

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16 pages, 5378 KiB

Open AccessArticle

An SOI CMOS-Based Multi-Sensor MEMS Chip for Fluidic Applications

by Mohtashim Mansoor^1,2,*, Ibraheem Haneef^1,3, Suhail Akhtar³, Muhammad Aftab Rafiq⁴, Andrea De Luca²

, Syed Zeeshan Ali⁵ and Florin Udrea^2,5

¹ Institute of Avionics and Aeronautics, Air University, E-9, Islamabad 44000, Pakistan

² Department of Engineering, University of Cambridge, 9-JJ Thomson Avenue, Cambridge CB3 0FA, UK

³ National University of Sciences & Technology (NUST), H-12, Islamabad 44000, Pakistan

⁴ Pakistan Institute of Engineering and Applied Sciences, Nilore, Islamabad 45650, Pakistan

⁵ Cambridge CMOS Sensors Ltd., Deanland House, 160-Cowley Road, Cambridge CB4 0DL, UK

Sensors 2016, 16(11), 1608; https://doi.org/10.3390/s16111608 - 4 Nov 2016

Cited by 27 | Viewed by 10070

Abstract

An SOI CMOS multi-sensor MEMS chip, which can simultaneously measure temperature, pressure and flow rate, has been reported. The multi-sensor chip has been designed keeping in view the requirements of researchers interested in experimental fluid dynamics. The chip contains ten thermodiodes (temperature sensors), [...] Read more.

An SOI CMOS multi-sensor MEMS chip, which can simultaneously measure temperature, pressure and flow rate, has been reported. The multi-sensor chip has been designed keeping in view the requirements of researchers interested in experimental fluid dynamics. The chip contains ten thermodiodes (temperature sensors), a piezoresistive-type pressure sensor and nine hot film-based flow rate sensors fabricated within the oxide layer of the SOI wafers. The silicon dioxide layers with embedded sensors are relieved from the substrate as membranes with the help of a single DRIE step after chip fabrication from a commercial CMOS foundry. Very dense sensor packing per unit area of the chip has been enabled by using technologies/processes like SOI, CMOS and DRIE. Independent apparatuses were used for the characterization of each sensor. With a drive current of 10 µA–0.1 µA, the thermodiodes exhibited sensitivities of 1.41 mV/°C–1.79 mV/°C in the range 20–300 °C. The sensitivity of the pressure sensor was 0.0686 mV/(V_excit kPa) with a non-linearity of 0.25% between 0 and 69 kPa above ambient pressure. Packaged in a micro-channel, the flow rate sensor has a linearized sensitivity of 17.3 mV/(L/min)^−0.1 in the tested range of 0–4.7 L/min. The multi-sensor chip can be used for simultaneous measurement of fluid pressure, temperature and flow rate in fluidic experiments and aerospace/automotive/biomedical/process industries. Full article

(This article belongs to the Special Issue Microfluidic Sensors and Control Devices)

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24 pages, 659 KiB

Open AccessArticle

A Flexible Approach for Human Activity Recognition Using Artificial Hydrocarbon Networks

by Hiram Ponce^*

, Luis Miralles-Pechuán and María De Lourdes Martínez-Villaseñor

Faculty of Engineering, Universidad Panamericana, 03920 Mexico City, Mexico

Sensors 2016, 16(11), 1715; https://doi.org/10.3390/s16111715 - 25 Oct 2016

Cited by 35 | Viewed by 7574

Abstract

Physical activity recognition based on sensors is a growing area of interest given the great advances in wearable sensors. Applications in various domains are taking advantage of the ease of obtaining data to monitor personal activities and behavior in order to deliver proactive [...] Read more.

Physical activity recognition based on sensors is a growing area of interest given the great advances in wearable sensors. Applications in various domains are taking advantage of the ease of obtaining data to monitor personal activities and behavior in order to deliver proactive and personalized services. Although many activity recognition systems have been developed for more than two decades, there are still open issues to be tackled with new techniques. We address in this paper one of the main challenges of human activity recognition: Flexibility. Our goal in this work is to present artificial hydrocarbon networks as a novel flexible approach in a human activity recognition system. In order to evaluate the performance of artificial hydrocarbon networks based classifier, experimentation was designed for user-independent, and also for user-dependent case scenarios. Our results demonstrate that artificial hydrocarbon networks classifier is flexible enough to be used when building a human activity recognition system with either user-dependent or user-independent approaches. Full article

(This article belongs to the Special Issue Advances in Artificial Intelligence: Selected Papers from MICAI 2013, 2014 and 2015—12th, 13th and 14th Mexican International Conferences on Artificial Intelligence)

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12 pages, 7324 KiB

Open AccessArticle

Design of the MEMS Piezoresistive Electronic Heart Sound Sensor

by Guojun Zhang^1,2,*,†, Mengran Liu^1,2,†, Nan Guo^1,2 and Wendong Zhang^1,2

¹ Science and Technology on Electronic Test & Measurement Laboratory, North University of China, Taiyuan 030051, China

² Key Laboratory of Instrumentation Science & Dynamic Measurement, Ministry of Education, North University of China, Taiyuan 030051, China

^† These authors contributed equally to this work.

Sensors 2016, 16(11), 1728; https://doi.org/10.3390/s16111728 - 7 Nov 2016

Cited by 30 | Viewed by 10144

Abstract

This paper proposes the electronic heart sound sensor, based on the piezoresistive principle and MEMS (Micro-Electro-Mechanical System) technology. Firstly, according to the characteristics of heart sound detection, the double-beam-block microstructure has been proposed, and the theoretical analysis and finite element method (FEM) simulation [...] Read more.

This paper proposes the electronic heart sound sensor, based on the piezoresistive principle and MEMS (Micro-Electro-Mechanical System) technology. Firstly, according to the characteristics of heart sound detection, the double-beam-block microstructure has been proposed, and the theoretical analysis and finite element method (FEM) simulation have been carried out. Combined with the natural frequency response of the heart sound (20~600 Hz), its structure sizes have been determined. Secondly, the processing technology of the microstructure with the stress concentration grooves has been developed. The material and sizes of the package have been determined by the three-layer medium transmission principle. Lastly, the MEMS piezoresistive electronic heart sound sensor has been tested compared with the 3200-type electronic stethoscope from 3M (São Paulo, MN, USA). The test results show that the heart sound waveform tested by the MEMS electronic heart sound sensor are almost the same as that tested by the 3200-type electronic stethoscope. Moreover, its signal-to-noise ratio is significantly higher. Compared with the traditional stethoscope, the MEMS heart sound sensor can provide the first and second heart sounds containing more abundant information about the lesion. Compared with the 3200-type electronic stethoscope from 3M, it has better performance and lower cost. Full article

(This article belongs to the Collection Modeling, Testing and Reliability Issues in MEMS Engineering)

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14 pages, 8795 KiB

Open AccessArticle

Development of an FPW Biosensor with Low Insertion Loss and High Fabrication Yield for Detection of Carcinoembryonic Antigen

by Je-Wei Lan¹, I-Yu Huang¹, Yu-Cheng Lin², Chang-Yu Lin³, Jian-Lin Chen⁴ and Chia-Hsu Hsieh^1,*

¹ Department of Electrical Engineering, National Sun Yat-sen University, Kaohsiung 80424, Taiwan

² Department of Engineering Science, National Cheng Kung University, Tainan 70101, Taiwan

³ Sunonwealth Electric Machine Industry Co. Ltd., Kaohsiung 80673, Taiwan

⁴ Powerchip Technology Corporation, Hsinchu 30078, Taiwan

Sensors 2016, 16(11), 1729; https://doi.org/10.3390/s16111729 - 8 Nov 2016

Cited by 14 | Viewed by 5889

Abstract

In the last two decades, various flexural plate-wave (FPW)-based biosensors with low phase velocity, low operation frequency, high sensitivity, and short response time, have been developed. However, conventional FPW transducers have low fabrication yield because controlling the thickness of silicon/isolation/metal/piezoelectric multilayer floating thin-plate [...] Read more.

In the last two decades, various flexural plate-wave (FPW)-based biosensors with low phase velocity, low operation frequency, high sensitivity, and short response time, have been developed. However, conventional FPW transducers have low fabrication yield because controlling the thickness of silicon/isolation/metal/piezoelectric multilayer floating thin-plate is difficult. Additionally, conventional FPW devices usually have high insertion loss because of wave energy dissipation to the silicon substrate or outside area of the output interdigital transducers (IDTs). These two disadvantages hinder the application of FPW devices. To reduce the high insertion loss of FPW devices, we designed two focus-type IDTs (fan-shaped and circular, respectively) that can effectively confine the launched wave energy, and adopted a focus-type silicon-grooved reflective grating structure (RGS) that can reduce the wave propagation loss. To accurately control the thickness of the silicon thin-plate and substantially improve the fabrication yield of FPW transducers, a 60 °C/27 °C two-step anisotropic wet etching process was developed. Compared with conventional FPW devices (with parallel-type IDTs and without RGS), the proposed FPW devices have lower insertion loss (36.04 dB) and higher fabrication yield (63.88%). Furthermore, by using cystamine-based self-assembled monolayer (SAM) nanotechnology, we used the improved FPW device to develop a novel FPW-based carcinoembryonic antigen (CEA) biosensor for detection of colorectal cancer, and this FPW-CEA biosensor has a low detection limit (5 ng/mL), short response time (<10 min), high sensitivity (60.16–70.06 cm²/g), and high sensing linearity (R-square = 0.859–0.980). Full article

(This article belongs to the Section Biosensors)

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17 pages, 3502 KiB

Open AccessArticle

In-Line Sorting of Harumanis Mango Based on External Quality Using Visible Imaging

by Mohd Firdaus Ibrahim^1,2,3,*

, Fathinul Syahir Ahmad Sa’ad^1,2, Ammar Zakaria^1,2

and Ali Yeon Md Shakaff^1,2

¹ Center of Excellence for Advanced Sensor Technology (CEASTech), Universiti Malaysia Perlis (UniMAP), Taman Muhibbah, Jejawi, Arau, Perlis 02600, Malaysia

² School of Mechatronics Engineering, Universiti Malaysia Perlis (UniMAP), Pauh Putra Campus, Arau, Perlis 02600, Malaysia

³ School of Bioprocess Engineering, Universiti Malaysia Perlis (UniMAP), Kompleks Pusat Pengajian Jejawi 3, Kawasan Perindustrian Jejawi, Arau, Perlis 02600, Malaysia

Sensors 2016, 16(11), 1753; https://doi.org/10.3390/s16111753 - 27 Oct 2016

Cited by 20 | Viewed by 8878

Abstract

The conventional method of grading Harumanis mango is time-consuming, costly and affected by human bias. In this research, an in-line system was developed to classify Harumanis mango using computer vision. The system was able to identify the irregularity of mango shape and its [...] Read more.

The conventional method of grading Harumanis mango is time-consuming, costly and affected by human bias. In this research, an in-line system was developed to classify Harumanis mango using computer vision. The system was able to identify the irregularity of mango shape and its estimated mass. A group of images of mangoes of different size and shape was used as database set. Some important features such as length, height, centroid and parameter were extracted from each image. Fourier descriptor and size-shape parameters were used to describe the mango shape while the disk method was used to estimate the mass of the mango. Four features have been selected by stepwise discriminant analysis which was effective in sorting regular and misshapen mango. The volume from water displacement method was compared with the volume estimated by image processing using paired t-test and Bland-Altman method. The result between both measurements was not significantly different (P > 0.05). The average correct classification for shape classification was 98% for a training set composed of 180 mangoes. The data was validated with another testing set consist of 140 mangoes which have the success rate of 92%. The same set was used for evaluating the performance of mass estimation. The average success rate of the classification for grading based on its mass was 94%. The results indicate that the in-line sorting system using machine vision has a great potential in automatic fruit sorting according to its shape and mass. Full article

(This article belongs to the Special Issue Sensors for Agriculture)

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20 pages, 4594 KiB

Open AccessArticle

Integrating Virtual Worlds with Tangible User Interfaces for Teaching Mathematics: A Pilot Study

by Graciela Guerrero¹

, Andrés Ayala², Juan Mateu², Laura Casades³ and Xavier Alamán^2,*

¹ Departamento de Ciencias de la Computación, Universidad de las Fuerzas Armadas ESPE, Sangolquí 171-5-231B, Ecuador

² Departamento de Ingeniería Informática, Universidad Autónoma de Madrid, Madrid 28049, Spain

³ Departamento de ciencias, Florida Secundaria High School, Catarroja 46470, Spain

Sensors 2016, 16(11), 1775; https://doi.org/10.3390/s16111775 - 25 Oct 2016

Cited by 21 | Viewed by 8856

Abstract

This article presents a pilot study of the use of two new tangible interfaces and virtual worlds for teaching geometry in a secondary school. The first tangible device allows the user to control a virtual object in six degrees of freedom. The second [...] Read more.

This article presents a pilot study of the use of two new tangible interfaces and virtual worlds for teaching geometry in a secondary school. The first tangible device allows the user to control a virtual object in six degrees of freedom. The second tangible device is used to modify virtual objects, changing attributes such as position, size, rotation and color. A pilot study on using these devices was carried out at the “Florida Secundaria” high school. A virtual world was built where students used the tangible interfaces to manipulate geometrical figures in order to learn different geometrical concepts. The pilot experiment results suggest that the use of tangible interfaces and virtual worlds allowed a more meaningful learning (concepts learnt were more durable). Full article

(This article belongs to the Special Issue Selected Papers from UCAmI, IWAAL and AmIHEALTH 2015)

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13 pages, 4093 KiB

Open AccessArticle

A Low Noise CMOS Readout Based on a Polymer-Coated SAW Array for Miniature Electronic Nose

by Cheng-Chun Wu, Szu-Chieh Liu, Shih-Wen Chiu and Kea-Tiong Tang^*

Department of Electrical Engineering, National Tsing Hua University/No. 101, Sec. 2, Kuang-Fu Road, Hsinchu 30013, Taiwan

Sensors 2016, 16(11), 1777; https://doi.org/10.3390/s16111777 - 25 Oct 2016

Cited by 4 | Viewed by 7044

Abstract

An electronic nose (E-Nose) is one of the applications for surface acoustic wave (SAW) sensors. In this paper, we present a low-noise complementary metal–oxide–semiconductor (CMOS) readout application-specific integrated circuit (ASIC) based on an SAW sensor array for achieving a miniature E-Nose. The center [...] Read more.

An electronic nose (E-Nose) is one of the applications for surface acoustic wave (SAW) sensors. In this paper, we present a low-noise complementary metal–oxide–semiconductor (CMOS) readout application-specific integrated circuit (ASIC) based on an SAW sensor array for achieving a miniature E-Nose. The center frequency of the SAW sensors was measured to be approximately 114 MHz. Because of interference between the sensors, we designed a low-noise CMOS frequency readout circuit to enable the SAW sensor to obtain frequency variation. The proposed circuit was fabricated in Taiwan Semiconductor Manufacturing Company (TSMC) 0.18 μm 1P6M CMOS process technology. The total chip size was nearly 1203 × 1203 μm². The chip was operated at a supply voltage of 1 V for a digital circuit and 1.8 V for an analog circuit. The least measurable difference between frequencies was 4 Hz. The detection limit of the system, when estimated using methanol and ethanol, was 0.1 ppm. Their linearity was in the range of 0.1 to 26,000 ppm. The power consumption levels of the analog and digital circuits were 1.742 mW and 761 μW, respectively. Full article

(This article belongs to the Special Issue The Use of New and/or Improved Materials for Sensing Applications)

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24 pages, 17406 KiB

Open AccessArticle

A Camera-Based Target Detection and Positioning UAV System for Search and Rescue (SAR) Purposes

by Jingxuan Sun, Boyang Li

, Yifan Jiang and Chih-yung Wen^*

Department of Mechanical Engineering, The Hong Kong Polytechnic University, Hong Kong, China

Sensors 2016, 16(11), 1778; https://doi.org/10.3390/s16111778 - 25 Oct 2016

Cited by 188 | Viewed by 23349

Abstract

Wilderness search and rescue entails performing a wide-range of work in complex environments and large regions. Given the concerns inherent in large regions due to limited rescue distribution, unmanned aerial vehicle (UAV)-based frameworks are a promising platform for providing aerial imaging. In recent [...] Read more.

Wilderness search and rescue entails performing a wide-range of work in complex environments and large regions. Given the concerns inherent in large regions due to limited rescue distribution, unmanned aerial vehicle (UAV)-based frameworks are a promising platform for providing aerial imaging. In recent years, technological advances in areas such as micro-technology, sensors and navigation have influenced the various applications of UAVs. In this study, an all-in-one camera-based target detection and positioning system is developed and integrated into a fully autonomous fixed-wing UAV. The system presented in this paper is capable of on-board, real-time target identification, post-target identification and location and aerial image collection for further mapping applications. Its performance is examined using several simulated search and rescue missions, and the test results demonstrate its reliability and efficiency. Full article

(This article belongs to the Special Issue UAV-Based Remote Sensing)

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9 pages, 3349 KiB

Open AccessArticle

Elimination of Drifts in Long-Duration Monitoring for Apnea-Hypopnea of Human Respiration

by Peng Jiang and Rong Zhu^*

State Key Laboratory of Precision Measurement Technology and Instrument, Department of Precision Instrument, Tsinghua University, Beijing 100084, China

Sensors 2016, 16(11), 1779; https://doi.org/10.3390/s16111779 - 25 Oct 2016

Cited by 5 | Viewed by 5302

Abstract

This paper reports a methodology to eliminate an uncertain baseline drift in respiratory monitoring using a thermal airflow sensor exposed in a high humidity environment. Human respiratory airflow usually contains a large amount of moisture (relative humidity, RH > 85%). Water vapors in [...] Read more.

This paper reports a methodology to eliminate an uncertain baseline drift in respiratory monitoring using a thermal airflow sensor exposed in a high humidity environment. Human respiratory airflow usually contains a large amount of moisture (relative humidity, RH > 85%). Water vapors in breathing air condense gradually on the surface of the sensor so as to form a thin water film that leads to a significant sensor drift in long-duration respiratory monitoring. The water film is formed by a combination of condensation and evaporation, and therefore the behavior of the humidity drift is complicated. Fortunately, the exhale and inhale responses of the sensor exhibit distinguishing features that are different from the humidity drift. Using a wavelet analysis method, we removed the baseline drift of the sensor and successfully recovered the respiratory waveform. Finally, we extracted apnea-hypopnea events from the respiratory signals monitored in whole-night sleeps of patients and compared them with golden standard polysomnography (PSG) results. Full article

(This article belongs to the Special Issue Wearable Biomedical Sensors)

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15 pages, 7307 KiB

Open AccessArticle

Electro-Mechanical Properties of Multilayer Graphene-Based Polymeric Composite Obtained through a Capillary Rise Method

by Chiara Acquarelli^1,2,*, Licia Paliotta^1,2

, Alessio Tamburrano^1,2

, Giovanni De Bellis^1,2 and Maria Sabrina Sarto^1,2

¹ Department of Astronautical, Electrical and Energy Engineering of Sapienza University of Rome (DIAEE), Via Eudossiana 18, Rome 00185, Italy

² Research Center for Nanotechnology Applied to Engineering of Sapienza University (CNIS), Rome 00185, Italy

Sensors 2016, 16(11), 1780; https://doi.org/10.3390/s16111780 - 25 Oct 2016

Cited by 12 | Viewed by 5552

Abstract

A new sensor made of a vinyl-ester polymer composite filled with multilayer graphene nanoplatelets (MLG) is produced through an innovative capillary rise method for application in strain sensing and structural health monitoring. The new sensor is characterized by high stability of the piezoresistive [...] Read more.

A new sensor made of a vinyl-ester polymer composite filled with multilayer graphene nanoplatelets (MLG) is produced through an innovative capillary rise method for application in strain sensing and structural health monitoring. The new sensor is characterized by high stability of the piezoresistive response under quasi-static consecutive loading/unloading cycles and monotonic tests. This is due to the peculiarity of the fabrication process that ensures a smooth and clean surface of the sensor, without the presence of filler agglomerates acting as micro- or macro-sized defects in the composite. Full article

(This article belongs to the Section Physical Sensors)

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18 pages, 5071 KiB

Open AccessArticle

One-Port Electronic Detection Strategies for Improving Sensitivity in Piezoelectric Resonant Sensor Measurements

by Zhongxu Hu¹, John Hedley^1,*

, Neil Keegan², Julia Spoors², Barry Gallacher¹ and Calum McNeil²

¹ School of Mechanical and Systems Engineering, Newcastle University, Newcastle upon Tyne NE1 7RU, UK

² Institute of Cellular Medicine, Newcastle University, Newcastle upon Tyne NE1 7RU, UK

Sensors 2016, 16(11), 1781; https://doi.org/10.3390/s16111781 - 25 Oct 2016

Cited by 12 | Viewed by 5690

Abstract

This paper describes a one-port mechanical resonance detection scheme utilized on a piezoelectric thin film driven silicon circular diaphragm resonator and discusses the limitations to such an approach in degenerate mode mass detection sensors. The sensor utilizes degenerated vibration modes of a radial [...] Read more.

This paper describes a one-port mechanical resonance detection scheme utilized on a piezoelectric thin film driven silicon circular diaphragm resonator and discusses the limitations to such an approach in degenerate mode mass detection sensors. The sensor utilizes degenerated vibration modes of a radial symmetrical microstructure thereby providing both a sense and reference mode allowing for minimization of environmental effects on performance. The circular diaphragm resonator was fabricated with thickness of 4.5 µm and diameter of 140 µm. A PZT thin film of 0.75 µm was patterned on the top surface for the purposes of excitation and vibration sensing. The device showed a resonant frequency of 5.8 MHz for the (1, 1) mode. An electronic interface circuit was designed to cancel out the large static and parasitic capacitance allowing for electrical detection of the mechanical vibration thereby enabling the frequency split between the sense and reference mode to be measured accurately. The extracted motional current, proportional to the vibration velocity, was fed back to the drive to effectively increase the Q factor, and therefore device sensitivity, by more than a factor of 8. A software phase-locked loop was implemented to automatically track the resonant frequencies to allow for faster and accurate resonance detection. Results showed that by utilizing the absolute mode frequencies as an indication of sensor temperature, the variation in sensor temperature due to the heating from the drive electronics was accounted for and led to an ultimate measurement sensitivity of 2.3 Hz. Full article

(This article belongs to the Section Physical Sensors)

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18 pages, 865 KiB

Open AccessArticle

Classification of Anticipatory Signals for Grasp and Release from Surface Electromyography

by Ho Chit Siu^1,*

, Julie A. Shah^1,2 and Leia A. Stirling^1,3

¹ Department of Aeronautics and Astronautics, Massachusetts Institute of Technology, 77 Massachusetts Ave, Cambridge, MA 02139, USA

² Computer Science and Artificial Intelligence Lab, Massachusetts Institute of Technology, 77 Massachusetts Ave, Cambridge, MA 02139, USA

³ Institute for Medical Engineering and Science, Massachusetts Institute of Technology, 77 Massachusetts Ave, Cambridge, MA 02139, USA

Sensors 2016, 16(11), 1782; https://doi.org/10.3390/s16111782 - 25 Oct 2016

Cited by 19 | Viewed by 6741

Abstract

Surface electromyography (sEMG) is a technique for recording natural muscle activation signals, which can serve as control inputs for exoskeletons and prosthetic devices. Previous experiments have incorporated these signals using both classical and pattern-recognition control methods in order to actuate such devices. We [...] Read more.

Surface electromyography (sEMG) is a technique for recording natural muscle activation signals, which can serve as control inputs for exoskeletons and prosthetic devices. Previous experiments have incorporated these signals using both classical and pattern-recognition control methods in order to actuate such devices. We used the results of an experiment incorporating grasp and release actions with object contact to develop an intent-recognition system based on Gaussian mixture models (GMM) and continuous-emission hidden Markov models (HMM) of sEMG data. We tested this system with data collected from 16 individuals using a forearm band with distributed sEMG sensors. The data contain trials with shifted band alignments to assess robustness to sensor placement. This study evaluated and found that pattern-recognition-based methods could classify transient anticipatory sEMG signals in the presence of shifted sensor placement and object contact. With the best-performing classifier, the effect of label lengths in the training data was also examined. A mean classification accuracy of 75.96% was achieved through a unigram HMM method with five mixture components. Classification accuracy on different sub-movements was found to be limited by the length of the shortest sub-movement, which means that shorter sub-movements within dynamic sequences require larger training sets to be classified correctly. This classification of user intent is a potential control mechanism for a dynamic grasping task involving user contact with external objects and noise. Further work is required to test its performance as part of an exoskeleton controller, which involves contact with actuated external surfaces. Full article

(This article belongs to the Special Issue Noninvasive Biomedical Sensors)

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18 pages, 2341 KiB

Open AccessArticle

Optimal Subset Selection of Time-Series MODIS Images and Sample Data Transfer with Random Forests for Supervised Classification Modelling

by Fuqun Zhou^* and Aining Zhang

Canada Centre for Remote Sensing, Natural Resources Canada, 560 Rochester Street, 6th Floor, Ottawa, ON K1A 0E4, Canada

Sensors 2016, 16(11), 1783; https://doi.org/10.3390/s16111783 - 25 Oct 2016

Cited by 15 | Viewed by 4643

Abstract

Nowadays, various time-series Earth Observation data with multiple bands are freely available, such as Moderate Resolution Imaging Spectroradiometer (MODIS) datasets including 8-day composites from NASA, and 10-day composites from the Canada Centre for Remote Sensing (CCRS). It is challenging to efficiently use these [...] Read more.

Nowadays, various time-series Earth Observation data with multiple bands are freely available, such as Moderate Resolution Imaging Spectroradiometer (MODIS) datasets including 8-day composites from NASA, and 10-day composites from the Canada Centre for Remote Sensing (CCRS). It is challenging to efficiently use these time-series MODIS datasets for long-term environmental monitoring due to their vast volume and information redundancy. This challenge will be greater when Sentinel 2–3 data become available. Another challenge that researchers face is the lack of in-situ data for supervised modelling, especially for time-series data analysis. In this study, we attempt to tackle the two important issues with a case study of land cover mapping using CCRS 10-day MODIS composites with the help of Random Forests’ features: variable importance, outlier identification. The variable importance feature is used to analyze and select optimal subsets of time-series MODIS imagery for efficient land cover mapping, and the outlier identification feature is utilized for transferring sample data available from one year to an adjacent year for supervised classification modelling. The results of the case study of agricultural land cover classification at a regional scale show that using only about a half of the variables we can achieve land cover classification accuracy close to that generated using the full dataset. The proposed simple but effective solution of sample transferring could make supervised modelling possible for applications lacking sample data. Full article

(This article belongs to the Section Remote Sensors)

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16 pages, 1902 KiB

Open AccessArticle

Optimal Parameter Exploration for Online Change-Point Detection in Activity Monitoring Using Genetic Algorithms

by Naveed Khan^1,*, Sally McClean¹, Shuai Zhang² and Chris Nugent²

¹ School of Computing and Information Engineering, Ulster University, Coleraine, Co., Londonderry BTT52 1SA, UK

² School of Computing and Mathematics, Ulster University, Jordanstown, Co., Antrim BT37 0QB, UK

Sensors 2016, 16(11), 1784; https://doi.org/10.3390/s16111784 - 26 Oct 2016

Cited by 10 | Viewed by 6533

Abstract

In recent years, smart phones with inbuilt sensors have become popular devices to facilitate activity recognition. The sensors capture a large amount of data, containing meaningful events, in a short period of time. The change points in this data are used to specify [...] Read more.

In recent years, smart phones with inbuilt sensors have become popular devices to facilitate activity recognition. The sensors capture a large amount of data, containing meaningful events, in a short period of time. The change points in this data are used to specify transitions to distinct events and can be used in various scenarios such as identifying change in a patient’s vital signs in the medical domain or requesting activity labels for generating real-world labeled activity datasets. Our work focuses on change-point detection to identify a transition from one activity to another. Within this paper, we extend our previous work on multivariate exponentially weighted moving average (MEWMA) algorithm by using a genetic algorithm (GA) to identify the optimal set of parameters for online change-point detection. The proposed technique finds the maximum accuracy and F_measure by optimizing the different parameters of the MEWMA, which subsequently identifies the exact location of the change point from an existing activity to a new one. Optimal parameter selection facilitates an algorithm to detect accurate change points and minimize false alarms. Results have been evaluated based on two real datasets of accelerometer data collected from a set of different activities from two users, with a high degree of accuracy from 99.4% to 99.8% and F_measure of up to 66.7%. Full article

(This article belongs to the Special Issue Selected Papers from UCAmI, IWAAL and AmIHEALTH 2015)

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11 pages, 2837 KiB

Open AccessArticle

Detection of Copper(II) Ions Using Glycine on Hydrazine-Adsorbed Gold Nanoparticles via Raman Spectroscopy

by Nguyễn Hoàng Ly¹

, Chulhun Seo² and Sang-Woo Joo^1,2,*

¹ Department of Chemistry, Soongsil University, Seoul 156-743, Korea

² Department of Information Communication, Materials, and Chemistry Convergence Technology, Soongsil University, Seoul 156-743, Korea

Sensors 2016, 16(11), 1785; https://doi.org/10.3390/s16111785 - 26 Oct 2016

Cited by 30 | Viewed by 9563

Abstract

A facile, selective, and sensitive detection method for the Cu²⁺ ions in environmental and biological solutions has been newly developed by observing the unique CN stretching peaks at ~2108 cm⁻¹ upon the dissociative adsorption of glycine (GLY) in hydrazine buffer on [...] Read more.

A facile, selective, and sensitive detection method for the Cu²⁺ ions in environmental and biological solutions has been newly developed by observing the unique CN stretching peaks at ~2108 cm⁻¹ upon the dissociative adsorption of glycine (GLY) in hydrazine buffer on gold nanoparticles (AuNPs). The relative abundance of Cu species on AuNPs was identified from X-ray photoelectron spectroscopy analysis. UV-Vis spectra also indicated that the Au particles aggregated to result in the color change owing to the destabilization induced by the GLY-Cu²⁺ complex. The CN stretching band at ~2108 cm⁻¹ could be observed to indicate the formation of the CN species from GLY on the hydrazine-covered AuNP surfaces. The other ions of Fe³⁺, Fe²⁺, Hg²⁺, Mg²⁺, Mn²⁺, Ni²⁺, Zn²⁺, Cr³⁺, Co²⁺, Cd²⁺, Pb²⁺, Ca²⁺, NH₄⁺, Na⁺, and K⁺ at high concentrations of 50 µM did not produce such spectral changes. The detection limit based on the CN band for the determination of the Cu²⁺ ion could be estimated to be as low as 500 nM in distilled water and 1 µM in river water, respectively. We attempted to apply our method to estimate intracellular ion detection in cancer cells for more practical purposes. Full article

(This article belongs to the Special Issue Colorimetric and Fluorescent Sensor)

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19 pages, 13230 KiB

Open AccessArticle

Development and Experimental Comparison of Low-Cost, Reliable Capacitive Touch Sensing Boards

by Ferat Akkoç^1,* and Özge Cihanbeğendi Şahin²

¹ Siemens AS, Corporate Technology Development Center, Kocaeli 41480, Turkey

² Department of Electrical and Electronic Engineering, Engineering Faculty, Dokuz Eylul University, Izmir 35390, Turkey

Sensors 2016, 16(11), 1786; https://doi.org/10.3390/s16111786 - 26 Oct 2016

Cited by 6 | Viewed by 11273

Abstract

In this study, two types of direct interface capacitive sensors, self- and mutual-capacitance, were developed and compared experimentally. Electromagnetic Compatibility (EMC) tests—International Electrotechnical Commission (IEC) 61000-4-3, IEC 61000-4-4, IEC 61000-4-6—were applied in an accredited laboratory to measure the immunity of the sensors against [...] Read more.

In this study, two types of direct interface capacitive sensors, self- and mutual-capacitance, were developed and compared experimentally. Electromagnetic Compatibility (EMC) tests—International Electrotechnical Commission (IEC) 61000-4-3, IEC 61000-4-4, IEC 61000-4-6—were applied in an accredited laboratory to measure the immunity of the sensors against radiated and conducted interference. The frequency hopping algorithm could be implemented for the mutual-capacitance sensor without using any particular circuit. The effects of EMC disturbance were detected by means of a new noise detection algorithm and when the signal-to-noise ratio (SNR) became lower, the operation frequency of the sensors switched to an undisturbed frequency to ensure safe operation. For this purpose, a new noise detection algorithm was developed and frequency hopping was performed with a standard controller. Both cards were tested under several conditions and their performances compared. Full article

(This article belongs to the Section Physical Sensors)

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14 pages, 4806 KiB

Open AccessReview

Conducting Polymers and Their Applications in Diabetes Management

by Yu Zhao^1,†

, Luyao Cao^1,†, Lanlan Li¹, Wen Cheng¹, Liangliang Xu², Xinyu Ping², Lijia Pan^1,* and Yi Shi^1,*

¹ School of Electronic Science and Engineering, Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing 210093, China

² Nanjing Foreign Language School, Nanjing 210008, China

^† These authors contributed equally to this work.

Sensors 2016, 16(11), 1787; https://doi.org/10.3390/s16111787 - 26 Oct 2016

Cited by 31 | Viewed by 9278

Abstract

Advances in conducting polymers (CPs) have promoted the development of diabetic monitoring and treatment, which is of great significance in human healthcare and modern medicine. CPs are special polymers with physical and electrochemical features resembling metals, inorganic semiconductors and non-conducting polymers. To improve [...] Read more.

Advances in conducting polymers (CPs) have promoted the development of diabetic monitoring and treatment, which is of great significance in human healthcare and modern medicine. CPs are special polymers with physical and electrochemical features resembling metals, inorganic semiconductors and non-conducting polymers. To improve and extend their properties, the fabrication of CPs and CP composites has attracted intensive attention in recent decades. Some CPs are biocompatible and suitable for biomedical use. Thus, the intriguing properties of CPs make wearable, noninvasive, continuous diabetes managing devices and other potential applications in diabetes possible in the near future. To highlight the recent advances of CPs and their derived materials (especially in conducting polymer hydrogels), here we discuss their fabrication and characterization, review the current state-of-the-art research in diabetes management based on these materials and describe current challenges as well as future potential research directions. Full article

(This article belongs to the Special Issue Glucose Sensors: Revolution in Diabetes Management 2016)

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1 pages, 141 KiB

Open AccessErratum

Erratum: Rodríguez-Navarro, D., et al. Mathematical Model and Calibration Procedure of a PSD Sensor Used in Local Positioning Systems. Sensors 2016, 16, 1484

by David Rodríguez-Navarro^1,*, José Luis Lázaro-Galilea¹

, Ignacio Bravo-Muñoz¹

, Alfredo Gardel-Vicente¹

, Francisco Domingo-Perez¹ and Georgios Tsirigotis²

¹ Department of electronics, University of Alcalá, Alcalá de Henares, Madrid 28801, Spain

² Informatics Engineering Department, Eastern Macedonia and Thrace Institute of Technology, Kvala 65404, Greece

Sensors 2016, 16(11), 1788; https://doi.org/10.3390/s16111788 - 26 Oct 2016

Cited by 1 | Viewed by 3267

Abstract

n/a Full article

(This article belongs to the Section Physical Sensors)

19 pages, 2357 KiB

Open AccessArticle

Preparation, Characterization and Activity of a Peptide-Cellulosic Aerogel Protease Sensor from Cotton

by J. Vincent Edwards^1,*, Krystal R. Fontenot¹, Nicolette T. Prevost¹, Nicole Pircher²

, Falk Liebner² and Brian D. Condon¹

¹ Southern Regional Research Center, USDA, New Orleans, LA 70124, USA

² Division of Chemistry of Renewable Resources, University of Natural Resources and Life Sciences Vienna, Konrad-Lorenz-Straße 24, Tulln an der Donau A-3430, Austria

Sensors 2016, 16(11), 1789; https://doi.org/10.3390/s16111789 - 26 Oct 2016

Cited by 37 | Viewed by 7797

Abstract

Nanocellulosic aerogels (NA) provide a lightweight biocompatible material with structural properties, like interconnected high porosity and specific surface area, suitable for biosensor design. We report here the preparation, characterization and activity of peptide-nanocellulose aerogels (PepNA) made from unprocessed cotton and designed with protease [...] Read more.

Nanocellulosic aerogels (NA) provide a lightweight biocompatible material with structural properties, like interconnected high porosity and specific surface area, suitable for biosensor design. We report here the preparation, characterization and activity of peptide-nanocellulose aerogels (PepNA) made from unprocessed cotton and designed with protease detection activity. Low-density cellulosic aerogels were prepared from greige cotton by employing calcium thiocyanate octahydrate/lithium chloride as a direct cellulose dissolving medium. Subsequent casting, coagulation, solvent exchange and supercritical carbon dioxide drying afforded homogeneous cellulose II aerogels of fibrous morphology. The cotton-based aerogel had a porosity of 99% largely dominated by mesopores (2–50 nm) and an internal surface of 163 m²·g⁻¹. A fluorescent tripeptide-substrate (succinyl-alanine-proline-alanine-4-amino-7-methyl-coumarin) was tethered to NA by (1) esterification of cellulose C6 surface hydroxyl groups with glycidyl-fluorenylmethyloxycarbonyl (FMOC), (2) deprotection and (3) coupling of the immobilized glycine with the tripeptide. Characterization of the NA and PepNA included techniques, such as elemental analysis, mass spectral analysis, attenuated total reflectance infrared imaging, nitrogen adsorption, scanning electron microscopy and bioactivity studies. The degree of substitution of the peptide analog attached to the anhydroglucose units of PepNA was 0.015. The findings from mass spectral analysis and attenuated total reflectance infrared imaging indicated that the peptide substrate was immobilized on to the surface of the NA. Nitrogen adsorption revealed a high specific surface area and a highly porous system, which supports the open porous structure observed from scanning electron microscopy images. Bioactivity studies of PepNA revealed a detection sensitivity of 0.13 units/milliliter for human neutrophil elastase, a diagnostic biomarker for inflammatory diseases. The physical properties of the aerogel are suitable for interfacing with an intelligent protease sequestrant wound dressing. Full article

(This article belongs to the Special Issue Point-of-Care Biosensors)

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21 pages, 3514 KiB

Open AccessArticle

Sensor Location Problem Optimization for Traffic Network with Different Spatial Distributions of Traffic Information

by Xu Bao¹

, Haijian Li^2,3,*

, Lingqiao Qin³

, Dongwei Xu⁴, Bin Ran³ and Jian Rong²

¹ Key Laboratory for Traffic and Transportation Security of Jiangsu Province, Huaiyin Institute of Technology, Huai’an 223003, China

² Beijing Key Laboratory of Traffic Engineering, Beijing University of Technology, Beijing 100124, China

³ Department of Civil and Environmental Engineering, University of Wisconsin-Madison, Madison, WI 53706, USA

⁴ College of Information Engineering, Zhejiang University of Technology, Hangzhou 310014, China

Sensors 2016, 16(11), 1790; https://doi.org/10.3390/s16111790 - 27 Oct 2016

Cited by 4 | Viewed by 6083

Abstract

To obtain adequate traffic information, the density of traffic sensors should be sufficiently high to cover the entire transportation network. However, deploying sensors densely over the entire network may not be realistic for practical applications due to the budgetary constraints of traffic management [...] Read more.

To obtain adequate traffic information, the density of traffic sensors should be sufficiently high to cover the entire transportation network. However, deploying sensors densely over the entire network may not be realistic for practical applications due to the budgetary constraints of traffic management agencies. This paper describes several possible spatial distributions of traffic information credibility and proposes corresponding different sensor information credibility functions to describe these spatial distribution properties. A maximum benefit model and its simplified model are proposed to solve the traffic sensor location problem. The relationships between the benefit and the number of sensors are formulated with different sensor information credibility functions. Next, expanding models and algorithms in analytic results are performed. For each case, the maximum benefit, the optimal number and spacing of sensors are obtained and the analytic formulations of the optimal sensor locations are derived as well. Finally, a numerical example is proposed to verify the validity and availability of the proposed models for solving a network sensor location problem. The results show that the optimal number of sensors of segments with different model parameters in an entire freeway network can be calculated. Besides, it can also be concluded that the optimal sensor spacing is independent of end restrictions but dependent on the values of model parameters that represent the physical conditions of sensors and roads. Full article

(This article belongs to the Special Issue Enabling the Move from Wireless Sensor Networks to Internet of Things and Cyber-Physical Systems)

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10 pages, 3546 KiB

Open AccessArticle

Nonenzymatic Glucose Sensor Based on In Situ Reduction of Ni/NiO-Graphene Nanocomposite

by Xiaohui Zhang^1,2,†, Zheng Zhang^1,*,†, Qingliang Liao¹, Shuo Liu¹, Zhuo Kang¹ and Yue Zhang^1,3,*

¹ State Key Laboratory for Advanced Metals and Materials, School of Materials Science and Engineering, University of Science and Technology Beijing, Beijing 100083, China

² CRRC Institute, Beijing 100070, China

³ Beijing Municipal Key Laboratory for Advanced Energy Materials and Technologies, Beijing 100083, China

^† These authors contributed equally to this work.

Sensors 2016, 16(11), 1791; https://doi.org/10.3390/s16111791 - 26 Oct 2016

Cited by 73 | Viewed by 11092

Abstract

Ni/NiO nanoflower modified reduced graphene oxide (rGO) nanocomposite (Ni/NiO-rGO) was introduced to screen printed electrode (SPE) for the construction of a nonenzymatic electrochemical glucose biosensor. The Ni/NiO-rGO nanocomposite was synthesized by an in situ reduction process. Graphene oxide (GO) hybrid Nafion sheets first [...] Read more.

Ni/NiO nanoflower modified reduced graphene oxide (rGO) nanocomposite (Ni/NiO-rGO) was introduced to screen printed electrode (SPE) for the construction of a nonenzymatic electrochemical glucose biosensor. The Ni/NiO-rGO nanocomposite was synthesized by an in situ reduction process. Graphene oxide (GO) hybrid Nafion sheets first chemical adsorbed Ni ions and assembled on the SPE. Subsequently, GO and Ni ions were reduced by hydrazine hydrate. The electrochemical properties of such a Ni/NiO-rGO modified SPE were carefully investigated. It showed a high activity for electrocatalytic oxidation of glucose in alkaline medium. The proposed nonenzymatic sensor can be utilized for quantification of glucose with a wide linear range from 29.9 μM to 6.44 mM (R = 0.9937) with a low detection limit of 1.8 μM (S/N = 3) and a high sensitivity of 1997 μA/mM∙cm⁻². It also exhibited good reproducibility as well as high selectivity. Full article

(This article belongs to the Special Issue Nanobiosensing for Sensors)

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13 pages, 932 KiB

Open AccessArticle

Skeleton-Based Abnormal Gait Detection

by Trong-Nguyen Nguyen^1,*, Huu-Hung Huynh² and Jean Meunier¹

¹ DIRO, University of Montreal, Montreal, QC H3T 1J4, Canada

² The University of Danang - University of Science and Technology, Danang 556361, Vietnam

Sensors 2016, 16(11), 1792; https://doi.org/10.3390/s16111792 - 26 Oct 2016

Cited by 72 | Viewed by 11600

Abstract

Human gait analysis plays an important role in musculoskeletal disorder diagnosis. Detecting anomalies in human walking, such as shuffling gait, stiff leg or unsteady gait, can be difficult if the prior knowledge of such a gait pattern is not available. We propose an [...] Read more.

Human gait analysis plays an important role in musculoskeletal disorder diagnosis. Detecting anomalies in human walking, such as shuffling gait, stiff leg or unsteady gait, can be difficult if the prior knowledge of such a gait pattern is not available. We propose an approach for detecting abnormal human gait based on a normal gait model. Instead of employing the color image, silhouette, or spatio-temporal volume, our model is created based on human joint positions (skeleton) in time series. We decompose each sequence of normal gait images into gait cycles. Each human instant posture is represented by a feature vector which describes relationships between pairs of bone joints located in the lower body. Such vectors are then converted into codewords using a clustering technique. The normal human gait model is created based on multiple sequences of codewords corresponding to different gait cycles. In the detection stage, a gait cycle with normality likelihood below a threshold, which is determined automatically in the training step, is assumed as an anomaly. The experimental results on both marker-based mocap data and Kinect skeleton show that our method is very promising in distinguishing normal and abnormal gaits with an overall accuracy of 90.12%. Full article

(This article belongs to the Collection Sensors for Globalized Healthy Living and Wellbeing)

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12 pages, 4289 KiB

Open AccessArticle

Detection and Identification of Multiple Stationary Human Targets Via Bio-Radar Based on the Cross-Correlation Method

by Yang Zhang^1,2,†, Fuming Chen^1,†

, Huijun Xue¹

, Zhao Li¹, Qiang An¹, Jianqi Wang^1,* and Yang Zhang^1,*

¹ Department of Biomedical Engineering, Fourth Military Medical University, Xi’an 710032, China

² Center for Disease Control and Prevention of Guangzhou Military Region, Guangzhou 510507, China

^† These authors contributed equally to this work and should be regarded as co-first author.

Sensors 2016, 16(11), 1793; https://doi.org/10.3390/s16111793 - 27 Oct 2016

Cited by 16 | Viewed by 6054

Abstract

Ultra-wideband (UWB) radar has been widely used for detecting human physiological signals (respiration, movement, etc.) in the fields of rescue, security, and medicine owing to its high penetrability and range resolution. In these applications, especially in rescue after disaster (earthquake, collapse, mine accident, [...] Read more.

Ultra-wideband (UWB) radar has been widely used for detecting human physiological signals (respiration, movement, etc.) in the fields of rescue, security, and medicine owing to its high penetrability and range resolution. In these applications, especially in rescue after disaster (earthquake, collapse, mine accident, etc.), the presence, number, and location of the trapped victims to be detected and rescued are the key issues of concern. Ample research has been done on the first issue, whereas the identification and localization of multi-targets remains a challenge. False positive and negative identification results are two common problems associated with the detection of multiple stationary human targets. This is mainly because the energy of the signal reflected from the target close to the receiving antenna is considerably stronger than those of the targets at further range, often leading to missing or false recognition if the identification method is based on the energy of the respiratory signal. Therefore, a novel method based on cross-correlation is proposed in this paper that is based on the relativity and periodicity of the signals, rather than on the energy. The validity of this method is confirmed through experiments using different scenarios; the results indicate a discernible improvement in the detection precision and identification of the multiple stationary targets. Full article

(This article belongs to the Special Issue Non-Contact Sensing)

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18 pages, 7116 KiB

Open AccessArticle

A 3D Optical Surface Profilometer Using a Dual-Frequency Liquid Crystal-Based Dynamic Fringe Pattern Generator

by Kyung-Il Joo^†, Mugeon Kim^†, Min-Kyu Park, Heewon Park, Byeonggon Kim, JoonKu Hahn and Hak-Rin Kim^*

¹ School of Electronics Engineering, Kyungpook National University, Daegu 41566, Korea

^† These authors contributed equally to this work.

Sensors 2016, 16(11), 1794; https://doi.org/10.3390/s16111794 - 27 Oct 2016

Cited by 8 | Viewed by 7707

Abstract

We propose a liquid crystal (LC)-based 3D optical surface profilometer that can utilize multiple fringe patterns to extract an enhanced 3D surface depth profile. To avoid the optical phase ambiguity and enhance the 3D depth extraction, 16 interference patterns were generated by the [...] Read more.

We propose a liquid crystal (LC)-based 3D optical surface profilometer that can utilize multiple fringe patterns to extract an enhanced 3D surface depth profile. To avoid the optical phase ambiguity and enhance the 3D depth extraction, 16 interference patterns were generated by the LC-based dynamic fringe pattern generator (DFPG) using four-step phase shifting and four-step spatial frequency varying schemes. The DFPG had one common slit with an electrically controllable birefringence (ECB) LC mode and four switching slits with a twisted nematic LC mode. The spatial frequency of the projected fringe pattern could be controlled by selecting one of the switching slits. In addition, moving fringe patterns were obtainable by applying voltages to the ECB LC layer, which varied the phase difference between the common and the selected switching slits. Notably, the DFPG switching time required to project 16 fringe patterns was minimized by utilizing the dual-frequency modulation of the driving waveform to switch the LC layers. We calculated the phase modulation of the DFPG and reconstructed the depth profile of 3D objects using a discrete Fourier transform method and geometric optical parameters. Full article

(This article belongs to the Special Issue Imaging: Sensors and Technologies)

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11 pages, 2106 KiB

Open AccessArticle

Comparison of Ultrasonic Welding and Thermal Bonding for the Integration of Thin Film Metal Electrodes in Injection Molded Polymeric Lab-on-Chip Systems for Electrochemistry

by Marco Matteucci^*

, Arto Heiskanen, Kinga Zór, Jenny Emnéus and Rafael Taboryski

Department of Micro- and Nanotechnology, Technical University of Denmark, Kongens Lyngby 2800, Denmark

Sensors 2016, 16(11), 1795; https://doi.org/10.3390/s16111795 - 27 Oct 2016

Cited by 15 | Viewed by 8526

Abstract

We compare ultrasonic welding (UW) and thermal bonding (TB) for the integration of embedded thin-film gold electrodes for electrochemical applications in injection molded (IM) microfluidic chips. The UW bonded chips showed a significantly superior electrochemical performance compared to the ones obtained using TB. [...] Read more.

We compare ultrasonic welding (UW) and thermal bonding (TB) for the integration of embedded thin-film gold electrodes for electrochemical applications in injection molded (IM) microfluidic chips. The UW bonded chips showed a significantly superior electrochemical performance compared to the ones obtained using TB. Parameters such as metal thickness of electrodes, depth of electrode embedding, delivered power, and height of energy directors (for UW), as well as pressure and temperature (for TB), were systematically studied to evaluate the two bonding methods and requirements for optimal electrochemical performance. The presented technology is intended for easy and effective integration of polymeric Lab-on-Chip systems to encourage their use in research, commercialization and education. Full article

(This article belongs to the Special Issue Microfluidics-Based Microsystem Integration Research)

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12 pages, 2731 KiB

Open AccessArticle

Portable Electronic Tongue Based on Microsensors for the Analysis of Cava Wines

by Pablo Giménez-Gómez¹, Roger Escudé-Pujol¹

, Fina Capdevila², Anna Puig-Pujol²

, Cecilia Jiménez-Jorquera¹ and Manuel Gutiérrez-Capitán^1,*

¹ Instituto de Microelectrónica de Barcelona (IMB-CNM), CSIC Campus UAB, 08193 Cerdanyola del Vallès, Spain

² Institut Català de la Vinya i el Vi (IRTA-INCAVI), Plaça Àgora 2, 08720 Vilafranca del Penedès, Spain

Sensors 2016, 16(11), 1796; https://doi.org/10.3390/s16111796 - 27 Oct 2016

Cited by 22 | Viewed by 7017

Abstract

Cava is a quality sparkling wine produced in Spain. As a product with a designation of origin, Cava wine has to meet certain quality requirements throughout its production process; therefore, the analysis of several parameters is of great interest. In this work, a [...] Read more.

Cava is a quality sparkling wine produced in Spain. As a product with a designation of origin, Cava wine has to meet certain quality requirements throughout its production process; therefore, the analysis of several parameters is of great interest. In this work, a portable electronic tongue for the analysis of Cava wine is described. The system is comprised of compact and low-power-consumption electronic equipment and an array of microsensors formed by six ion-selective field effect transistors sensitive to pH, Na⁺, K⁺, Ca²⁺, Cl⁻, and CO₃²⁻, one conductivity sensor, one redox potential sensor, and two amperometric gold microelectrodes. This system, combined with chemometric tools, has been applied to the analysis of 78 Cava wine samples. Results demonstrate that the electronic tongue is able to classify the samples according to the aging time, with a percentage of correct prediction between 80% and 96%, by using linear discriminant analysis, as well as to quantify the total acidity, pH, volumetric alcoholic degree, potassium, conductivity, glycerol, and methanol parameters, with mean relative errors between 2.3% and 6.0%, by using partial least squares regressions. Full article

(This article belongs to the Special Issue Olfactory and Gustatory Sensors)

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10 pages, 9820 KiB

Open AccessArticle

Electrochemical Behavior and Determination of Chlorogenic Acid Based on Multi-Walled Carbon Nanotubes Modified Screen-Printed Electrode

by Xiaoyan Ma^1,2, Hongqiao Yang^1,2, Huabin Xiong^1,2, Xiaofen Li^1,2, Jinting Gao^1,2 and Yuntao Gao^1,2,*

¹ The Engineering Laboratory of Polylactic Acid-Based Functional Materials of Yunnan, School of Chemistry and Environment, Yunnan Minzu University, Kunming 650500, China

² Key Laboratory of Chemistry in Ethnic Medicinal Resources, State Ethnic Affairs Commission & Ministry of Education, Yunnan Minzu University, Kunming 650500, China

Sensors 2016, 16(11), 1797; https://doi.org/10.3390/s16111797 - 27 Oct 2016

Cited by 39 | Viewed by 6221

Abstract

In this paper, the multi-walled carbon nanotubes modified screen-printed electrode (MWCNTs/SPE) was prepared and the MWCNTs/SPE was employed for the electrochemical determination of the antioxidant substance chlorogenic acids (CGAs). A pair of well-defined redox peaks of CGA was observed at the MWCNTs/SPE in [...] Read more.

In this paper, the multi-walled carbon nanotubes modified screen-printed electrode (MWCNTs/SPE) was prepared and the MWCNTs/SPE was employed for the electrochemical determination of the antioxidant substance chlorogenic acids (CGAs). A pair of well-defined redox peaks of CGA was observed at the MWCNTs/SPE in 0.10 mol/L acetic acid-sodium acetate buffer (pH 6.2) and the electrode process was adsorption-controlled. Cyclic voltammetry (CV) and differential pulse voltammetry (DPV) methods for the determination of CGA were proposed based on the MWCNTs/SPE. Under the optimal conditions, the proposed method exhibited linear ranges from 0.17 to 15.8 µg/mL, and the linear regression equation was Ipa (µA) = 4.1993 C (×10⁻⁵ mol/L) + 1.1039 (r = 0.9976) and the detection limit for CGA could reach 0.12 µg/mL. The recovery of matrine was 94.74%–106.65% (RSD = 2.92%) in coffee beans. The proposed method is quick, sensitive, reliable, and can be used for the determination of CGA. Full article

(This article belongs to the Special Issue Recent Advances in Biosensors Based Screen Printed Platforms)

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37 pages, 2083 KiB

Open AccessArticle

Information Fusion of Conflicting Input Data

by Uwe Mönks^1,*

, Helene Dörksen¹, Volker Lohweg¹ and Michael Hübner²

¹ inIT—Institute Industrial IT, Ostwestfalen-Lippe University of Applied Sciences, Lemgo 32657, Germany

² ESIT—Embedded Systems for Information Technology, Ruhr-University Bochum, Bochum 44801, Germany

Sensors 2016, 16(11), 1798; https://doi.org/10.3390/s16111798 - 29 Oct 2016

Cited by 25 | Viewed by 9055

Abstract

Sensors, and also actuators or external sources such as databases, serve as data sources in order to realise condition monitoring of industrial applications or the acquisition of characteristic parameters like production speed or reject rate. Modern facilities create such a large amount of [...] Read more.

Sensors, and also actuators or external sources such as databases, serve as data sources in order to realise condition monitoring of industrial applications or the acquisition of characteristic parameters like production speed or reject rate. Modern facilities create such a large amount of complex data that a machine operator is unable to comprehend and process the information contained in the data. Thus, information fusion mechanisms gain increasing importance. Besides the management of large amounts of data, further challenges towards the fusion algorithms arise from epistemic uncertainties (incomplete knowledge) in the input signals as well as conflicts between them. These aspects must be considered during information processing to obtain reliable results, which are in accordance with the real world. The analysis of the scientific state of the art shows that current solutions fulfil said requirements at most only partly. This article proposes the multilayered information fusion system MACRO (multilayer attribute-based conflict-reducing observation) employing the μBalTLCS (fuzzified balanced two-layer conflict solving) fusion algorithm to reduce the impact of conflicts on the fusion result. The performance of the contribution is shown by its evaluation in the scope of a machine condition monitoring application under laboratory conditions. Here, the MACRO system yields the best results compared to state-of-the-art fusion mechanisms. The utilised data is published and freely accessible. Full article

(This article belongs to the Special Issue Advances in Multi-Sensor Information Fusion: Theory and Applications)

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15 pages, 1065 KiB

Open AccessArticle

A Novel Group Decision-Making Method Based on Sensor Data and Fuzzy Information

by Yu-Ting Bai¹, Bai-Hai Zhang^1,*, Xiao-Yi Wang², Xue-Bo Jin²

, Ji-Ping Xu², Ting-Li Su² and Zhao-Yang Wang¹

¹ School of Automation, Beijing Institute of Technology, Beijing 100081, China

² School of Computer and Information Engineering, Beijing Technology and Business University, Beijing 100048, China

Sensors 2016, 16(11), 1799; https://doi.org/10.3390/s16111799 - 28 Oct 2016

Cited by 10 | Viewed by 4394

Abstract

Algal bloom is a typical phenomenon of the eutrophication of rivers and lakes and makes the water dirty and smelly. It is a serious threat to water security and public health. Most scholars studying solutions for this pollution have studied the principles of [...] Read more.

Algal bloom is a typical phenomenon of the eutrophication of rivers and lakes and makes the water dirty and smelly. It is a serious threat to water security and public health. Most scholars studying solutions for this pollution have studied the principles of remediation approaches, but few have studied the decision-making and selection of the approaches. Existing research uses simplex decision-making information which is highly subjective and uses little of the data from water quality sensors. To utilize these data and solve the rational decision-making problem, a novel group decision-making method is proposed using the sensor data with fuzzy evaluation information. Firstly, the optimal similarity aggregation model of group opinions is built based on the modified similarity measurement of Vague values. Secondly, the approaches’ ability to improve the water quality indexes is expressed using Vague evaluation methods. Thirdly, the water quality sensor data are analyzed to match the features of the alternative approaches with grey relational degrees. This allows the best remediation approach to be selected to meet the current water status. Finally, the selection model is applied to the remediation of algal bloom in lakes. The results show this method’s rationality and feasibility when using different data from different sources. Full article

(This article belongs to the Special Issue Advances in Multi-Sensor Information Fusion: Theory and Applications)

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8 pages, 2445 KiB

Open AccessArticle

An Optical Fiber Sensor and Its Application in UAVs for Current Measurements

by Felipe S. Delgado, João P. Carvalho, Thiago V. N. Coelho^* and Alexandre B. Dos Santos

Electrical Circuit Department, Federal University of Juiz de Fora, Juiz de Fora 36036-330, Brazil

Sensors 2016, 16(11), 1800; https://doi.org/10.3390/s16111800 - 27 Oct 2016

Cited by 20 | Viewed by 6205

Abstract

In this paper, we propose and experimentally investigate an optical sensor based on a novel combination of a long-period fiber grating (LPFG) with a permanent magnet to measure electrical current in unmanned aerial vehicles (UAVs). The proposed device uses a neodymium magnet attached [...] Read more.

In this paper, we propose and experimentally investigate an optical sensor based on a novel combination of a long-period fiber grating (LPFG) with a permanent magnet to measure electrical current in unmanned aerial vehicles (UAVs). The proposed device uses a neodymium magnet attached to the grating structure, which suffers from an electromagnetic force produced when the current flows in the wire of the UAV engine. Therefore, it causes deformation on the sensor and thus, different shifts occur in the resonant bands of the transmission spectrum of the LPFG. Finally, the results show that it is possible to monitor electrical current throughout the entire operating range of the UAV engine from 0 A to 10 A in an effective and practical way with good linearity, reliability and response time, which are desirable characteristics in electrical current sensing. Full article

(This article belongs to the Special Issue Recent Advances in Fiber Bragg Grating Sensing)

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19 pages, 4510 KiB

Open AccessArticle

Comparison of Reflectance Measurements Acquired with a Contact Probe and an Integration Sphere: Implications for the Spectral Properties of Vegetation at a Leaf Level

by Markéta Potůčková^1,*

, Lucie Červená¹

, Lucie Kupková¹, Zuzana Lhotáková²

, Petr Lukeš³, Jan Hanuš³, Jan Novotný³ and Jana Albrechtová²

¹ Department of Applied Geoinformatics and Cartography, Faculty of Science, Charles University in Prague, Albertov 6, 128 43 Prague 2, Czech Republic

² Department of Experimental Plant Biology, Faculty of Science, Charles University in Prague, Viničná 5, 128 44 Prague 2, Czech Republic

³ Global Change Research Institute, Academy of Sciences of the Czech Republic, v.v.i., Bělidla 986/4a, 603 00 Brno, Czech Republic

Sensors 2016, 16(11), 1801; https://doi.org/10.3390/s16111801 - 28 Oct 2016

Cited by 20 | Viewed by 7567

Abstract

Laboratory spectroscopy in visible and infrared regions is an important tool for studies dealing with plant ecophysiology and early recognition of plant stress due to changing environmental conditions. Leaf optical properties are typically acquired with a spectroradiometer coupled with an integration sphere (IS) [...] Read more.

Laboratory spectroscopy in visible and infrared regions is an important tool for studies dealing with plant ecophysiology and early recognition of plant stress due to changing environmental conditions. Leaf optical properties are typically acquired with a spectroradiometer coupled with an integration sphere (IS) in a laboratory or with a contact probe (CP), which has the advantage of operating flexibility and the provision of repetitive in-situ reflectance measurements. Experiments comparing reflectance spectra measured with different devices and device settings are rarely reported in literature. Thus, in our study we focused on a comparison of spectra collected with two ISs on identical samples ranging from a Spectralon and coloured papers as reference standards to vegetation samples with broadleaved (Nicotiana Rustica L.) and coniferous (Picea abies L. Karst.) leaf types. First, statistical measures such as mean absolute difference, median of differences, standard deviation and paired-sample t-test were applied in order to evaluate differences between collected reflectance values. The possibility of linear transformation between spectra was also tested. Moreover, correlation between normalised differential indexes (NDI) derived for each device and all combinations of wavelengths between 450 nm and 1800 nm were assessed. Finally, relationships between laboratory measured leaf compounds (total chlorophyll, carotenoids and water content), NDI and selected spectral indices often used in remote sensing were studied. The results showed differences between spectra acquired with different devices. While differences were negligible in the case of the Spectralon and they were possible to be modelled with a linear transformation in the case of coloured papers, the spectra collected with the CP and the ISs differed significantly in the case of vegetation samples. Regarding the spectral indices calculated from the reflectance data collected with the three devices, their mean values were in the range of the corresponding standard deviations in the case of broadleaved leaf type. Larger differences in optical leaf properties of spruce needles collected with the CP and ISs are implicated from the different measurement procedure due to needle-like leaf where shoots with spatially oriented needles were measured with the CP and individual needles with the IS. The study shows that a direct comparison between the spectra collected with two devices is not advisable as spectrally dependent offsets may likely exist. We propose that the future studies shall focus on standardisation of measurement procedures so that open access spectral libraries could serve as a reliable input for modelling of optical properties on a leaf level. Full article

(This article belongs to the Section Remote Sensors)

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13 pages, 4480 KiB

Open AccessArticle

Complementary Split-Ring Resonator-Loaded Microfluidic Ethanol Chemical Sensor

by Ahmed Salim and Sungjoon Lim^*

School of Electrical and Electronics Engineering, College of Engineering, Chung-Ang University, 221 Heukseok-Dong, Dongjak-Gu, Seoul 156-756, Korea

Sensors 2016, 16(11), 1802; https://doi.org/10.3390/s16111802 - 28 Oct 2016

Cited by 220 | Viewed by 12080

Abstract

In this paper, a complementary split-ring resonator (CSRR)-loaded patch is proposed as a microfluidic ethanol chemical sensor. The primary objective of this chemical sensor is to detect ethanol’s concentration. First, two tightly coupled concentric CSRRs loaded on a patch are realized on a [...] Read more.

In this paper, a complementary split-ring resonator (CSRR)-loaded patch is proposed as a microfluidic ethanol chemical sensor. The primary objective of this chemical sensor is to detect ethanol’s concentration. First, two tightly coupled concentric CSRRs loaded on a patch are realized on a Rogers RT/Duroid 5870 substrate, and then a microfluidic channel engraved on polydimethylsiloxane (PDMS) is integrated for ethanol chemical sensor applications. The resonant frequency of the structure before loading the microfluidic channel is 4.72 GHz. After loading the microfluidic channel, the 550 MHz shift in the resonant frequency is ascribed to the dielectric perturbation phenomenon when the ethanol concentration is varied from 0% to 100%. In order to assess the sensitivity range of our proposed sensor, various concentrations of ethanol are tested and analyzed. Our proposed sensor exhibits repeatability and successfully detects 10% ethanol as verified by the measurement set-up. It has created headway to a miniaturized, non-contact, low-cost, reliable, reusable, and easily fabricated design using extremely small liquid volumes. Full article

(This article belongs to the Special Issue Microfluidics-Based Microsystem Integration Research)

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12 pages, 8982 KiB

Open AccessArticle

Electrochemical Aptasensor for Myoglobin-Specific Recognition Based on Porphyrin Functionalized Graphene-Conjugated Gold Nanocomposites

by Guojuan Zhang^1,2, Zhiguang Liu¹, Li Wang¹

and Yujing Guo^1,*

¹ Institute of Environmental Science, Shanxi University, Taiyuan 030006, China

² College of Chemistry and Chemical Engineering, Shanxi University, Taiyuan 030006, China

Sensors 2016, 16(11), 1803; https://doi.org/10.3390/s16111803 - 28 Oct 2016

Cited by 31 | Viewed by 7024

Abstract

In this work, a novel electrochemical aptasensor was developed for sensitive and selective detection of myoglobin based on meso-tetra (4-carboxyphenyl) porphyrin-functionalized graphene-conjugated gold nanoparticles (TCPP–Gr/AuNPs). Due to its good electric conductivity, large specific surface area, and excellent mechanical properties, TCPP–Gr/AuNPs can act as [...] Read more.

In this work, a novel electrochemical aptasensor was developed for sensitive and selective detection of myoglobin based on meso-tetra (4-carboxyphenyl) porphyrin-functionalized graphene-conjugated gold nanoparticles (TCPP–Gr/AuNPs). Due to its good electric conductivity, large specific surface area, and excellent mechanical properties, TCPP–Gr/AuNPs can act as an enhanced material for the electrochemical detection of myoglobin. Meanwhile, it provides an effective matrix for immobilizing myoglobin-binding aptamer (MbBA). The electrochemical aptasensor has a sensitive response to myoglobin in a linear range from 2.0 × 10⁻¹¹ M to 7.7 × 10⁻⁷ M with a detection limit of 6.7 × 10⁻¹² M (S/N = 3). Furthermore, the method has the merits of high sensitivity, low price, and high specificity. Our work will supply new horizons for the diagnostic applications of graphene-based materials in biomedicine and biosensors. Full article

(This article belongs to the Special Issue Nanobiosensing for Sensors)

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14 pages, 11745 KiB

Open AccessArticle

Two-Time Scale Virtual Sensor Design for Vibration Observation of a Translational Flexible-Link Manipulator Based on Singular Perturbation and Differential Games

by Jinyong Ju, Wei Li, Yuqiao Wang^*, Mengbao Fan and Xuefeng Yang

School of Mechatronic Engineering, China University of Mining and Technology, Xuzhou 221116, China

Sensors 2016, 16(11), 1804; https://doi.org/10.3390/s16111804 - 28 Oct 2016

Cited by 14 | Viewed by 5160

Abstract

Effective feedback control requires all state variable information of the system. However, in the translational flexible-link manipulator (TFM) system, it is unrealistic to measure the vibration signals and their time derivative of any points of the TFM by infinite sensors. With the rigid-flexible [...] Read more.

Effective feedback control requires all state variable information of the system. However, in the translational flexible-link manipulator (TFM) system, it is unrealistic to measure the vibration signals and their time derivative of any points of the TFM by infinite sensors. With the rigid-flexible coupling between the global motion of the rigid base and the elastic vibration of the flexible-link manipulator considered, a two-time scale virtual sensor, which includes the speed observer and the vibration observer, is designed to achieve the estimation for the vibration signals and their time derivative of the TFM, as well as the speed observer and the vibration observer are separately designed for the slow and fast subsystems, which are decomposed from the dynamic model of the TFM by the singular perturbation. Additionally, based on the linear-quadratic differential games, the observer gains of the two-time scale virtual sensor are optimized, which aims to minimize the estimation error while keeping the observer stable. Finally, the numerical calculation and experiment verify the efficiency of the designed two-time scale virtual sensor. Full article

(This article belongs to the Special Issue Advanced Robotics and Mechatronics Devices)

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44 pages, 1124 KiB

Open AccessReview

Driver Distraction Using Visual-Based Sensors and Algorithms

by Alberto Fernández^1,*, Rubén Usamentiaga²

, Juan Luis Carús¹

and Rubén Casado²

¹ Grupo TSK, Technological Scientific Park of Gijón, 33203 Gijón, Asturias, Spain

² Department of Computer Science and Engineering, University of Oviedo, Campus de Viesques, 33204 Gijón, Asturias, Spain

Sensors 2016, 16(11), 1805; https://doi.org/10.3390/s16111805 - 28 Oct 2016

Cited by 102 | Viewed by 21899

Abstract

Driver distraction, defined as the diversion of attention away from activities critical for safe driving toward a competing activity, is increasingly recognized as a significant source of injuries and fatalities on the roadway. Additionally, the trend towards increasing the use of in-vehicle information [...] Read more.

Driver distraction, defined as the diversion of attention away from activities critical for safe driving toward a competing activity, is increasingly recognized as a significant source of injuries and fatalities on the roadway. Additionally, the trend towards increasing the use of in-vehicle information systems is critical because they induce visual, biomechanical and cognitive distraction and may affect driving performance in qualitatively different ways. Non-intrusive methods are strongly preferred for monitoring distraction, and vision-based systems have appeared to be attractive for both drivers and researchers. Biomechanical, visual and cognitive distractions are the most commonly detected types in video-based algorithms. Many distraction detection systems only use a single visual cue and therefore, they may be easily disturbed when occlusion or illumination changes appear. Moreover, the combination of these visual cues is a key and challenging aspect in the development of robust distraction detection systems. These visual cues can be extracted mainly by using face monitoring systems but they should be completed with more visual cues (e.g., hands or body information) or even, distraction detection from specific actions (e.g., phone usage). Additionally, these algorithms should be included in an embedded device or system inside a car. This is not a trivial task and several requirements must be taken into account: reliability, real-time performance, low cost, small size, low power consumption, flexibility and short time-to-market. The key points for the development and implementation of sensors to carry out the detection of distraction will also be reviewed. This paper shows a review of the role of computer vision technology applied to the development of monitoring systems to detect distraction. Some key points considered as both future work and challenges ahead yet to be solved will also be addressed. Full article

(This article belongs to the Special Issue Imaging: Sensors and Technologies)

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24 pages, 8756 KiB

Open AccessArticle

Wheelchair Navigation System for Disabled and Elderly People

by Eun Yi Kim

Visual Information Processing Lab., Konkuk University, Seoul 143-701, Korea

Sensors 2016, 16(11), 1806; https://doi.org/10.3390/s16111806 - 28 Oct 2016

Cited by 38 | Viewed by 16784

Abstract

An intelligent wheelchair (IW) system is developed in order to support safe mobility for disabled or elderly people with various impairments. The proposed IW offers two main functions: obstacle detection and avoidance, and situation recognition. First, through a combination of a vision sensor [...] Read more.

An intelligent wheelchair (IW) system is developed in order to support safe mobility for disabled or elderly people with various impairments. The proposed IW offers two main functions: obstacle detection and avoidance, and situation recognition. First, through a combination of a vision sensor and eight ultrasonic ones, it detects diverse obstacles and produces occupancy grid maps (OGMs) that describe environmental information, including the positions and sizes of obstacles, which is then given to the learning-based algorithm. By learning the common patterns among OGMs assigned to the same directions, the IW can automatically find paths to prevent collisions with obstacles. Second, it distinguishes a situation whereby the user is standing on a sidewalk, traffic intersection, or roadway through analyzing the texture and shape of the images, which aids in preventing any accidents that would result in fatal injuries to the user, such as collisions with vehicles. From the experiments that were performed in various environments, we can prove the following: (1) the proposed system can recognize different types of outdoor places with 98.3% accuracy; and (2) it can produce paths that avoid obstacles with 92.0% accuracy. Full article

(This article belongs to the Collection Sensors for Globalized Healthy Living and Wellbeing)

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23 pages, 14141 KiB

Open AccessArticle

When Ultrasonic Sensors and Computer Vision Join Forces for Efficient Obstacle Detection and Recognition

by Bogdan Mocanu^1,2,†, Ruxandra Tapu^1,2,*,† and Titus Zaharia¹

¹ ARTEMIS Department, Institut Mines-Télécom/Télécom SudParis, UMR CNRS MAP5 8145, 9 rue Charles Fourier, Évry 91000, France

² Telecommunication Department, Faculty of ETTI, University Politehnica of Bucharest, Splaiul Independentei 313, Bucharest 060042, Romania

^† These authors contributed equally to this paper.

Sensors 2016, 16(11), 1807; https://doi.org/10.3390/s16111807 - 28 Oct 2016

Cited by 89 | Viewed by 18615

Abstract

In the most recent report published by the World Health Organization concerning people with visual disabilities it is highlighted that by the year 2020, worldwide, the number of completely blind people will reach 75 million, while the number of visually impaired (VI) people [...] Read more.

In the most recent report published by the World Health Organization concerning people with visual disabilities it is highlighted that by the year 2020, worldwide, the number of completely blind people will reach 75 million, while the number of visually impaired (VI) people will rise to 250 million. Within this context, the development of dedicated electronic travel aid (ETA) systems, able to increase the safe displacement of VI people in indoor/outdoor spaces, while providing additional cognition of the environment becomes of outmost importance. This paper introduces a novel wearable assistive device designed to facilitate the autonomous navigation of blind and VI people in highly dynamic urban scenes. The system exploits two independent sources of information: ultrasonic sensors and the video camera embedded in a regular smartphone. The underlying methodology exploits computer vision and machine learning techniques and makes it possible to identify accurately both static and highly dynamic objects existent in a scene, regardless on their location, size or shape. In addition, the proposed system is able to acquire information about the environment, semantically interpret it and alert users about possible dangerous situations through acoustic feedback. To determine the performance of the proposed methodology we have performed an extensive objective and subjective experimental evaluation with the help of 21 VI subjects from two blind associations. The users pointed out that our prototype is highly helpful in increasing the mobility, while being friendly and easy to learn. Full article

(This article belongs to the Special Issue Sensing Technology for Healthcare System)

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7 pages, 949 KiB

Open AccessTechnical Note

Quantitative Raman Spectroscopy Analysis of Polyhydroxyalkanoates Produced by Cupriavidus necator H16

by Ota Samek^1,*, Stanislav Obruča², Martin Šiler¹, Petr Sedláček²

, Pavla Benešová², Dan Kučera², Ivana Márova², Jan Ježek¹, Silva Bernatová¹ and Pavel Zemánek¹

¹ Institute of Scientific Instruments of the CAS, Brno 61264, Czech Republic

² Materials Research Centre, Faculty of Chemistry, Brno University of Technology, Brno 61200, Czech Republic

Sensors 2016, 16(11), 1808; https://doi.org/10.3390/s16111808 - 28 Oct 2016

Cited by 32 | Viewed by 9359

Abstract

We report herein on the application of Raman spectroscopy to the rapid quantitative analysis of polyhydroxyalkanoates (PHAs), biodegradable polyesters accumulated by various bacteria. This theme was exemplified for quantitative detection of the most common member of PHAs, poly(3-hydroxybutyrate) (PHB) in Cupriavidus necator H16. [...] Read more.

We report herein on the application of Raman spectroscopy to the rapid quantitative analysis of polyhydroxyalkanoates (PHAs), biodegradable polyesters accumulated by various bacteria. This theme was exemplified for quantitative detection of the most common member of PHAs, poly(3-hydroxybutyrate) (PHB) in Cupriavidus necator H16. We have identified the relevant spectral region (800–1800 cm⁻¹) incorporating the Raman emission lines exploited for the calibration of PHB (PHB line at 1736 cm⁻¹) and for the selection of the two internal standards (DNA at 786 cm⁻¹ and Amide I at 1662 cm⁻¹). In order to obtain quantitative data for calibration of intracellular content of PHB in bacterial cells reference samples containing PHB amounts—determined by gas chromatography—from 12% to 90% (w/w) were used. Consequently, analytical results based on this calibration can be used for fast and reliable determination of intracellular PHB content during biotechnological production of PHB since the whole procedure—from bacteria sampling, centrifugation, and sample preparation to Raman analysis—can take about 12 min. In contrast, gas chromatography analysis takes approximately 8 h. Full article

(This article belongs to the Special Issue Applications of Raman Spectroscopy in Biosensors)

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24 pages, 14866 KiB

Open AccessArticle

3D Tracking via Shoe Sensing

by Fangmin Li^1,2,*

, Guo Liu², Jian Liu³, Xiaochuang Chen² and Xiaolin Ma²

¹ Department of Mathematics and Computer Science, Changsha University, Changsha 410022, China

² Key Laboratory of Fiber Optical Sensing Technology and Information Processing, Ministry of Education, School of Information Engineering, Wuhan University of Technology, Wuhan 430070, China

³ Department of Electrical and Computer Engineering, Stevens Institute of Technology, Hoboken, NJ 07030, USA

Sensors 2016, 16(11), 1809; https://doi.org/10.3390/s16111809 - 28 Oct 2016

Cited by 10 | Viewed by 5496

Abstract

Most location-based services are based on a global positioning system (GPS), which only works well in outdoor environments. Compared to outdoor environments, indoor localization has created more buzz in recent years as people spent most of their time indoors working at offices and [...] Read more.

Most location-based services are based on a global positioning system (GPS), which only works well in outdoor environments. Compared to outdoor environments, indoor localization has created more buzz in recent years as people spent most of their time indoors working at offices and shopping at malls, etc. Existing solutions mainly rely on inertial sensors (i.e., accelerometer and gyroscope) embedded in mobile devices, which are usually not accurate enough to be useful due to the mobile devices’ random movements while people are walking. In this paper, we propose the use of shoe sensing (i.e., sensors attached to shoes) to achieve 3D indoor positioning. Specifically, a short-time energy-based approach is used to extract the gait pattern. Moreover, in order to improve the accuracy of vertical distance estimation while the person is climbing upstairs, a state classification is designed to distinguish the walking status including plane motion (i.e., normal walking and jogging horizontally), walking upstairs, and walking downstairs. Furthermore, we also provide a mechanism to reduce the vertical distance accumulation error. Experimental results show that we can achieve nearly 100% accuracy when extracting gait patterns from walking/jogging with a low-cost shoe sensor, and can also achieve 3D indoor real-time positioning with high accuracy. Full article

(This article belongs to the Special Issue New Paradigms in Cyber-Physical Social Sensing)

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20 pages, 603 KiB

Open AccessArticle

Component-Based Modelling for Scalable Smart City Systems Interoperability: A Case Study on Integrating Energy Demand Response Systems

by Esther Palomar^1,*, Xiaohong Chen², Zhiming Liu³, Sabita Maharjan⁴ and Jonathan Bowen⁵

¹ School of Computing and Digital Technology, Birmingham City University, Birmingham B4 7XG, UK

² Department of Computer Science, University of Illinois at Urbana-Champaign, Champaign, IL 61801, USA

³ Centre for Research and Innovation in Software Engineering, Southwest University, Chongqing 400700, China

⁴ Networks Department, Simula Research Laboratory, Fornebu 1364, Norway

⁵ School of Engineering, London South Bank University, London SE1 0AA, UK

Sensors 2016, 16(11), 1810; https://doi.org/10.3390/s16111810 - 28 Oct 2016

Cited by 23 | Viewed by 6871

Abstract

Smart city systems embrace major challenges associated with climate change, energy efficiency, mobility and future services by embedding the virtual space into a complex cyber-physical system. Those systems are constantly evolving and scaling up, involving a wide range of integration among users, devices, [...] Read more.

Smart city systems embrace major challenges associated with climate change, energy efficiency, mobility and future services by embedding the virtual space into a complex cyber-physical system. Those systems are constantly evolving and scaling up, involving a wide range of integration among users, devices, utilities, public services and also policies. Modelling such complex dynamic systems’ architectures has always been essential for the development and application of techniques/tools to support design and deployment of integration of new components, as well as for the analysis, verification, simulation and testing to ensure trustworthiness. This article reports on the definition and implementation of a scalable component-based architecture that supports a cooperative energy demand response (DR) system coordinating energy usage between neighbouring households. The proposed architecture, called refinement of Cyber-Physical Component Systems (rCPCS), which extends the refinement calculus for component and object system (rCOS) modelling method, is implemented using Eclipse Extensible Coordination Tools (ECT), i.e., Reo coordination language. With rCPCS implementation in Reo, we specify the communication, synchronisation and co-operation amongst the heterogeneous components of the system assuring, by design scalability and the interoperability, correctness of component cooperation. Full article

(This article belongs to the Special Issue Smart City: Vision and Reality)

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22 pages, 1994 KiB

Open AccessArticle

An Accurate Direction Finding Scheme Using Virtual Antenna Array via Smartphones

by Xiaopu Wang, Yan Xiong and Wenchao Huang^*

School of Computer Science and Technology, University of Science and Technology of China, Hefei 230000, China

Sensors 2016, 16(11), 1811; https://doi.org/10.3390/s16111811 - 29 Oct 2016

Cited by 4 | Viewed by 5962

Abstract

With the development of localization technologies, researchers solve the indoor localization problems using diverse methods and equipment. Most localization techniques require either specialized devices or fingerprints, which are inconvenient for daily use. Therefore, we propose and implement an accurate, efficient and lightweight system [...] Read more.

With the development of localization technologies, researchers solve the indoor localization problems using diverse methods and equipment. Most localization techniques require either specialized devices or fingerprints, which are inconvenient for daily use. Therefore, we propose and implement an accurate, efficient and lightweight system for indoor direction finding using common smartphones and loudspeakers. Our method is derived from a key insight: By moving a smartphone in regular patterns, we can effectively emulate the sensitivity and functionality of a Uniform Antenna Array to estimate the angle of arrival of the target signal. Specifically, a user only needs to hold his smartphone still in front of him, and then rotate his body around

360^{\circ}

duration with the smartphone at an approximate constant velocity. Then, our system can provide accurate directional guidance and lead the user to their destinations (normal loudspeakers we preset in the indoor environment transmitting high frequency acoustic signals) after a few measurements. Major challenges in implementing our system are not only imitating a virtual antenna array by ordinary smartphones but also overcoming the detection difficulties caused by the complex indoor environment. In addition, we leverage the gyroscope of the smartphone to reduce the impact of a user’s motion pattern change to the accuracy of our system. In order to get rid of the multipath effect, we leverage multiple signal classification to calculate the direction of the target signal, and then design and deploy our system in various indoor scenes. Extensive comparative experiments show that our system is reliable under various circumstances. Full article

(This article belongs to the Special Issue Advanced Algorithms for Mobile Sensing: from Wireless Sensor Networks to Mobile Crowd Sensing)

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19 pages, 2723 KiB

Open AccessArticle

Towards Contactless Silent Speech Recognition Based on Detection of Active and Visible Articulators Using IR-UWB Radar

by Young Hoon Shin^1,2 and Jiwon Seo^1,2,*

¹ School of Integrated Technology, College of Engineering, Yonsei University, 85 Songdogwahak-ro, Yeonsu-gu, Incheon 21983, Korea

² Yonsei Institute of Convergence Technology, Yonsei University, 85 Songdogwahak-ro, Yeonsu-gu, Incheon 21983, Korea

Sensors 2016, 16(11), 1812; https://doi.org/10.3390/s16111812 - 29 Oct 2016

Cited by 30 | Viewed by 8534

Abstract

People with hearing or speaking disabilities are deprived of the benefits of conventional speech recognition technology because it is based on acoustic signals. Recent research has focused on silent speech recognition systems that are based on the motions of a speaker’s vocal tract [...] Read more.

People with hearing or speaking disabilities are deprived of the benefits of conventional speech recognition technology because it is based on acoustic signals. Recent research has focused on silent speech recognition systems that are based on the motions of a speaker’s vocal tract and articulators. Because most silent speech recognition systems use contact sensors that are very inconvenient to users or optical systems that are susceptible to environmental interference, a contactless and robust solution is hence required. Toward this objective, this paper presents a series of signal processing algorithms for a contactless silent speech recognition system using an impulse radio ultra-wide band (IR-UWB) radar. The IR-UWB radar is used to remotely and wirelessly detect motions of the lips and jaw. In order to extract the necessary features of lip and jaw motions from the received radar signals, we propose a feature extraction algorithm. The proposed algorithm noticeably improved speech recognition performance compared to the existing algorithm during our word recognition test with five speakers. We also propose a speech activity detection algorithm to automatically select speech segments from continuous input signals. Thus, speech recognition processing is performed only when speech segments are detected. Our testbed consists of commercial off-the-shelf radar products, and the proposed algorithms are readily applicable without designing specialized radar hardware for silent speech processing. Full article

(This article belongs to the Section Physical Sensors)

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16 pages, 16637 KiB

Open AccessArticle

An Efficient Method of Sharing Mass Spatio-Temporal Trajectory Data Based on Cloudera Impala for Traffic Distribution Mapping in an Urban City

by Lianjie Zhou^1,†

, Nengcheng Chen^1,2,*,†

, Sai Yuan^1,† and Zeqiang Chen^1,2

¹ State Key Laboratory for Information Engineering in Surveying, Mapping and Remote Sensing, Wuhan University, 129 Luoyu Road, Wuhan 430079, China

² Collaborative Innovation Center of Geospatial Technology, 129 Luoyu Road, Wuhan 430079, China

^† These authors contributed equally to this work.

Sensors 2016, 16(11), 1813; https://doi.org/10.3390/s16111813 - 29 Oct 2016

Cited by 6 | Viewed by 7169

Abstract

The efficient sharing of spatio-temporal trajectory data is important to understand traffic congestion in mass data. However, the data volumes of bus networks in urban cities are growing rapidly, reaching daily volumes of one hundred million datapoints. Accessing and retrieving mass spatio-temporal trajectory [...] Read more.

The efficient sharing of spatio-temporal trajectory data is important to understand traffic congestion in mass data. However, the data volumes of bus networks in urban cities are growing rapidly, reaching daily volumes of one hundred million datapoints. Accessing and retrieving mass spatio-temporal trajectory data in any field is hard and inefficient due to limited computational capabilities and incomplete data organization mechanisms. Therefore, we propose an optimized and efficient spatio-temporal trajectory data retrieval method based on the Cloudera Impala query engine, called ESTRI, to enhance the efficiency of mass data sharing. As an excellent query tool for mass data, Impala can be applied for mass spatio-temporal trajectory data sharing. In ESTRI we extend the spatio-temporal trajectory data retrieval function of Impala and design a suitable data partitioning method. In our experiments, the Taiyuan BeiDou (BD) bus network is selected, containing 2300 buses with BD positioning sensors, producing 20 million records every day, resulting in two difficulties as described in the Introduction section. In addition, ESTRI and MongoDB are applied in experiments. The experiments show that ESTRI achieves the most efficient data retrieval compared to retrieval using MongoDB for data volumes of fifty million, one hundred million, one hundred and fifty million, and two hundred million. The performance of ESTRI is approximately seven times higher than that of MongoDB. The experiments show that ESTRI is an effective method for retrieving mass spatio-temporal trajectory data. Finally, bus distribution mapping in Taiyuan city is achieved, describing the buses density in different regions at different times throughout the day, which can be applied in future studies of transport, such as traffic scheduling, traffic planning and traffic behavior management in intelligent public transportation systems. Full article

(This article belongs to the Special Issue Urban Remote Sensing: Monitoring, Synthesis and Modeling in the Urban Environment)

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13 pages, 8668 KiB

Open AccessArticle

Whispering Gallery Mode Thermometry

by Simone Corbellini¹, Chiara Ramella¹

, Lili Yu^2,*, Marco Pirola¹

and Vito Fernicola^3,*

¹ Department of Electronics and Telecommunications, Politecnico di Torino, Corso Duca degli Abruzzi 24, Torino 10129, Italy

² College of Electrical Engineering and Control Science, Nanjing Tech University, Nanjing 211816, China

³ Istituto Nazionale di Ricerca Metrologica, Strada delle Cacce 91, Torino 10135, Italy

Sensors 2016, 16(11), 1814; https://doi.org/10.3390/s16111814 - 29 Oct 2016

Cited by 11 | Viewed by 5897

Abstract

This paper presents a state-of-the-art whispering gallery mode (WGM) thermometer system, which could replace platinum resistance thermometers currently used in many industrial applications, thus overcoming some of their well-known limitations and their potential for providing lower measurement uncertainty. The temperature-sensing element is a [...] Read more.

This paper presents a state-of-the-art whispering gallery mode (WGM) thermometer system, which could replace platinum resistance thermometers currently used in many industrial applications, thus overcoming some of their well-known limitations and their potential for providing lower measurement uncertainty. The temperature-sensing element is a sapphire-crystal-based whispering gallery mode resonator with the main resonant modes between 10 GHz and 20 GHz. In particular, it was found that the WGM around 13.6 GHz maximizes measurement performance, affording sub-millikelvin resolution and temperature stability of better than 1 mK at 0 °C. The thermometer system was made portable and low-cost by developing an ad hoc interrogation system (hardware and software) able to achieve an accuracy in the order of a few parts in 10⁹ in the determination of resonance frequencies. Herein we report the experimental assessment of the measurement stability, repeatability and resolution, and the calibration of the thermometer in the temperature range from −74 °C to 85 °C. The combined standard uncertainty for a single temperature calibration point is found to be within 5 mK (i.e., comparable with state-of-the-art for industrial thermometry), and is mainly due to the employed calibration setup. The uncertainty contribution of the WGM thermometer alone is within a millikelvin. Full article

(This article belongs to the Special Issue Resonator Sensors)

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16 pages, 2346 KiB

Open AccessReview

Understanding the Potential of WO₃ Based Sensors for Breath Analysis

by Anna Staerz^1,2,†, Udo Weimar^1,2,† and Nicolae Barsan^1,2,*,†

¹ Institute of Physical and Theoretical Chemistry (IPTC), University of Tuebingen, Auf der Morgenstelle 15, D-72076 Tuebingen, Germany

² Center for Light-Matter Interaction, Sensors & Analytics (LISA+), University of Tuebingen, Auf der Morgenstelle 15, D-72076 Tuebingen, Germany

^† These authors contributed equally to this work.

Sensors 2016, 16(11), 1815; https://doi.org/10.3390/s16111815 - 29 Oct 2016

Cited by 91 | Viewed by 10987

Abstract

Tungsten trioxide is the second most commonly used semiconducting metal oxide in gas sensors. Semiconducting metal oxide (SMOX)-based sensors are small, robust, inexpensive and sensitive, making them highly attractive for handheld portable medical diagnostic detectors. WO₃ is reported to show high sensor [...] Read more.

Tungsten trioxide is the second most commonly used semiconducting metal oxide in gas sensors. Semiconducting metal oxide (SMOX)-based sensors are small, robust, inexpensive and sensitive, making them highly attractive for handheld portable medical diagnostic detectors. WO₃ is reported to show high sensor responses to several biomarkers found in breath, e.g., acetone, ammonia, carbon monoxide, hydrogen sulfide, toluene, and nitric oxide. Modern material science allows WO₃ samples to be tailored to address certain sensing needs. Utilizing recent advances in breath sampling it will be possible in the future to test WO₃-based sensors in application conditions and to compare the sensing results to those obtained using more expensive analytical methods. Full article

(This article belongs to the Special Issue Gas Sensors for Health Care and Medical Applications)

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21 pages, 1788 KiB

Open AccessArticle

A Reference Model for Monitoring IoT WSN-Based Applications

by Juan Vicente Capella^*

, José Carlos Campelo

, Alberto Bonastre

and Rafael Ors

Instituto ITACA, Universitat Politècnica de València, Ciutat Politècnica de la Innovació, Camino de Vera s/n, 46022 Valencia, Spain

Sensors 2016, 16(11), 1816; https://doi.org/10.3390/s16111816 - 30 Oct 2016

Cited by 35 | Viewed by 9010

Abstract

The Internet of Things (IoT) is, at this moment, one of the most promising technologies that has arisen for decades. Wireless Sensor Networks (WSNs) are one of the main pillars for many IoT applications, insofar as they require to obtain context-awareness information. The [...] Read more.

The Internet of Things (IoT) is, at this moment, one of the most promising technologies that has arisen for decades. Wireless Sensor Networks (WSNs) are one of the main pillars for many IoT applications, insofar as they require to obtain context-awareness information. The bibliography shows many difficulties in their real implementation that have prevented its massive deployment. Additionally, in IoT environments where data producers and data consumers are not directly related, compatibility and certification issues become fundamental. Both problems would profit from accurate knowledge of the internal behavior of WSNs that must be obtained by the utilization of appropriate tools. There are many ad-hoc proposals with no common structure or methodology, and intended to monitor a particular WSN. To overcome this problem, this paper proposes a structured three-layer reference model for WSN Monitoring Platforms (WSN-MP), which offers a standard environment for the design of new monitoring platforms to debug, verify and certify a WSN’s behavior and performance, and applicable to every WSN. This model also allows the comparative analysis of the current proposals for monitoring the operation of WSNs. Following this methodology, it is possible to achieve a standardization of WSN-MP, promoting new research areas in order to solve the problems of each layer. Full article

(This article belongs to the Special Issue Enabling the Move from Wireless Sensor Networks to Internet of Things and Cyber-Physical Systems)

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20 pages, 5306 KiB

Open AccessArticle

Signal Conditioning for the Kalman Filter: Application to Satellite Attitude Estimation with Magnetometer and Sun Sensors

by Segundo Esteban^1,*

, Jose M. Girón-Sierra¹, Óscar R. Polo²

and Manuel Angulo³

¹ Department of Computer Architecture and Automatic Control, Faculty of Physic Sciences, Complutense University of Madrid, Madrid 28040, Spain

² Department of Computer Engineering, University of Alcala, Alcalá de Henares 28871, Spain

³ Department of Space Programs, INTA, Torrejón de Ardoz 28850, Spain

Sensors 2016, 16(11), 1817; https://doi.org/10.3390/s16111817 - 31 Oct 2016

Cited by 11 | Viewed by 7890

Abstract

Most satellites use an on-board attitude estimation system, based on available sensors. In the case of low-cost satellites, which are of increasing interest, it is usual to use magnetometers and Sun sensors. A Kalman filter is commonly recommended for the estimation, to simultaneously [...] Read more.

Most satellites use an on-board attitude estimation system, based on available sensors. In the case of low-cost satellites, which are of increasing interest, it is usual to use magnetometers and Sun sensors. A Kalman filter is commonly recommended for the estimation, to simultaneously exploit the information from sensors and from a mathematical model of the satellite motion. It would be also convenient to adhere to a quaternion representation. This article focuses on some problems linked to this context. The state of the system should be represented in observable form. Singularities due to alignment of measured vectors cause estimation problems. Accommodation of the Kalman filter originates convergence difficulties. The article includes a new proposal that solves these problems, not needing changes in the Kalman filter algorithm. In addition, the article includes assessment of different errors, initialization values for the Kalman filter; and considers the influence of the magnetic dipole moment perturbation, showing how to handle it as part of the Kalman filter framework. Full article

(This article belongs to the Special Issue State-of-the-Art Sensors Technology in Spain 2016)

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16 pages, 5005 KiB

Open AccessArticle

Modelling of XCO₂ Surfaces Based on Flight Tests of TanSat Instruments

by Li Li Zhang¹, Tian Xiang Yue^1,*, John P. Wilson^1,2, Ding Yi Wang³

, Na Zhao¹, Yu Liu¹, Dong Dong Liu³, Zheng Ping Du¹, Yi Fu Wang¹, Chao Lin⁴, Yu Quan Zheng⁴ and Jian Hong Guo¹

¹ State Key Laboratory of Resources and Environment Information System, Institute of Geographical Sciences and Natural Resources Research, Chinese Academy of Sciences, Beijing 100101, China

² Spatial Sciences Institute, Dana and David Dornsife College of Letters, Arts, and Sciences, University of Southern California, Los Angeles, CA 90089-0374, USA

³ Ministry of Education Key Laboratory for Nonequilibrium Synthesis and Modulation of Condensed Matter, School of Science, Xi’an Jiaotong University, Xi’an 710049, China

⁴ Changchun Institute of Optics, Fine Mechanics and Physics, Chinese Academy of Sciences, Changchun 130033, China

Sensors 2016, 16(11), 1818; https://doi.org/10.3390/s16111818 - 1 Nov 2016

Cited by 12 | Viewed by 6139

Abstract

The TanSat carbon satellite is to be launched at the end of 2016. In order to verify the performance of its instruments, a flight test of TanSat instruments was conducted in Jilin Province in September, 2015. The flight test area covered a total [...] Read more.

The TanSat carbon satellite is to be launched at the end of 2016. In order to verify the performance of its instruments, a flight test of TanSat instruments was conducted in Jilin Province in September, 2015. The flight test area covered a total area of about 11,000 km² and the underlying surface cover included several lakes, forest land, grassland, wetland, farmland, a thermal power plant and numerous cities and villages. We modeled the column-average dry-air mole fraction of atmospheric carbon dioxide (XCO₂) surface based on flight test data which measured the near- and short-wave infrared (NIR) reflected solar radiation in the absorption bands at around 760 and 1610 nm. However, it is difficult to directly analyze the spatial distribution of XCO₂ in the flight area using the limited flight test data and the approximate surface of XCO₂, which was obtained by regression modeling, which is not very accurate either. We therefore used the high accuracy surface modeling (HASM) platform to fill the gaps where there is no information on XCO₂ in the flight test area, which takes the approximate surface of XCO₂ as its driving field and the XCO₂ observations retrieved from the flight test as its optimum control constraints. High accuracy surfaces of XCO₂ were constructed with HASM based on the flight’s observations. The results showed that the mean XCO₂ in the flight test area is about 400 ppm and that XCO₂ over urban areas is much higher than in other places. Compared with OCO-2’s XCO₂, the mean difference is 0.7 ppm and the standard deviation is 0.95 ppm. Therefore, the modelling of the XCO₂ surface based on the flight test of the TanSat instruments fell within an expected and acceptable range. Full article

(This article belongs to the Section Remote Sensors)

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33 pages, 7899 KiB

Open AccessReview

Wafer-Level Vacuum Packaging of Smart Sensors

by Allan Hilton^* and Dorota S. Temple

Electronics and Applied Physics Division, RTI International, Research Triangle Park, NC 27709, USA

Sensors 2016, 16(11), 1819; https://doi.org/10.3390/s16111819 - 31 Oct 2016

Cited by 63 | Viewed by 21822

Abstract

The reach and impact of the Internet of Things will depend on the availability of low-cost, smart sensors—“low cost” for ubiquitous presence, and “smart” for connectivity and autonomy. By using wafer-level processes not only for the smart sensor fabrication and integration, but also [...] Read more.

The reach and impact of the Internet of Things will depend on the availability of low-cost, smart sensors—“low cost” for ubiquitous presence, and “smart” for connectivity and autonomy. By using wafer-level processes not only for the smart sensor fabrication and integration, but also for packaging, we can further greatly reduce the cost of sensor components and systems as well as further decrease their size and weight. This paper reviews the state-of-the-art in the wafer-level vacuum packaging technology of smart sensors. We describe the processes needed to create the wafer-scale vacuum microchambers, focusing on approaches that involve metal seals and that are compatible with the thermal budget of complementary metal-oxide semiconductor (CMOS) integrated circuits. We review choices of seal materials and structures that are available to a device designer, and present techniques used for the fabrication of metal seals on device and window wafers. We also analyze the deposition and activation of thin film getters needed to maintain vacuum in the ultra-small chambers, and the wafer-to-wafer bonding processes that form the hermetic seal. We discuss inherent trade-offs and challenges of each seal material set and the corresponding bonding processes. Finally, we identify areas for further research that could help broaden implementations of the wafer-level vacuum packaging technology. Full article

(This article belongs to the Section Physical Sensors)

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11 pages, 4758 KiB

Open AccessArticle

A Photoactivated Gas Detector for Toluene Sensing at Room Temperature Based on New Coral-Like ZnO Nanostructure Arrays

by Li-Ko Yeh^1,†, Jie-Chun Luo^1,†, Min-Chun Chen², Chih-Hung Wu³, Jian-Zhang Chen³

, I-Chun Cheng⁴, Cheng-Che Hsu² and Wei-Cheng Tian^1,4,5,*

¹ Graduate Institute of Electronics Engineering, National Taiwan University, Taipei City 10617, Taiwan

² Department of Chemical Engineering, National Taiwan University, Taipei City 10617, Taiwan

³ Graduate Institute of Applied Mechanics, National Taiwan University, Taipei City 10617, Taiwan

⁴ Department of Electrical Engineering, National Taiwan University, Taipei City 10617, Taiwan

⁵ Graduate Institute of Biomedical Electronics and Bioinformatics, National Taiwan University, Taipei City 10617, Taiwan

^† These authors contributed equally to the work.

Sensors 2016, 16(11), 1820; https://doi.org/10.3390/s16111820 - 31 Oct 2016

Cited by 10 | Viewed by 6937

Abstract

A photoactivated gas detector operated at room temperature was microfabricated using a simple hydrothermal method. We report that the photoactivated gas detector can detect toluene using a UV illumination of 2 μW/cm². By ultraviolet (UV) illumination, gas detectors sense toluene at [...] Read more.

A photoactivated gas detector operated at room temperature was microfabricated using a simple hydrothermal method. We report that the photoactivated gas detector can detect toluene using a UV illumination of 2 μW/cm². By ultraviolet (UV) illumination, gas detectors sense toluene at room temperature without heating. A significant enhancement of detector sensitivity is achieved because of the high surface-area-to-volume ratio of the morphology of the coral-like ZnO nanorods arrays (NRAs) and the increased number of photo-induced oxygen ions under UV illumination. The corresponding sensitivity (ΔR/R₀) of the detector based on coral-like ZnO NRAs is enhanced by approximately 1022% compared to that of thin-film detectors. The proposed detector greatly extends the dynamic range of detection of metal-oxide-based detectors for gas sensing applications. We report the first-ever detection of toluene with a novel coral-like NRAs gas detector at room temperature. A sensing mechanism model is also proposed to explain the sensing responses of gas detectors based on coral-like ZnO NRAs. Full article

(This article belongs to the Special Issue Materials and Applications for Sensors and Transducers)

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7 pages, 1999 KiB

Open AccessArticle

Sensitivity and 3 dB Bandwidth in Single and Series-Connected Tunneling Magnetoresistive Sensors

by Michał Dąbek^1,2,*, Piotr Wiśniowski¹

, Tomasz Stobiecki¹, Jerzy Wrona³, Susana Cardoso^4,5

and Paulo P. Freitas^4,5,6

¹ Department of Electronics, AGH University of Science and Technology, Krakow 30-059, Poland

² Silicon Creations, 49 Highway 23 NE, Suwanee 30024, GA, USA

³ Singulus Technologies AG, Kahl am Main 63796, Germany

⁴ INESC-MN and IN, Lisbon 1000-029, Portugal

⁵ Physics Department, Instituto Superior Tecnico, Universidade de Lisboa, Lisbon 1600-276, Portugal

⁶ INL-International Iberian Nanotechnology Laboratory, Avenida Mestre José Veiga s/n, Braga 4715-330, Portugal

Sensors 2016, 16(11), 1821; https://doi.org/10.3390/s16111821 - 31 Oct 2016

Cited by 6 | Viewed by 5820

Abstract

As single tunneling magnetoresistive (TMR) sensor performance in modern high-speed applications is limited by breakdown voltage and saturation of the sensitivity, for higher voltage applications (i.e., compatible to 1.8 V, 3.3 V or 5 V standards) practically only a series connection can be [...] Read more.

As single tunneling magnetoresistive (TMR) sensor performance in modern high-speed applications is limited by breakdown voltage and saturation of the sensitivity, for higher voltage applications (i.e., compatible to 1.8 V, 3.3 V or 5 V standards) practically only a series connection can be applied. Thus, in this study we focused on sensitivity, 3 dB bandwidth and sensitivity-bandwidth product (SBP) dependence on the DC bias voltage in single and series-connected TMR sensors. We show that, below breakdown voltage, the strong bias influence on sensitivity and the 3 dB frequency of a single sensor results in higher SBP than in a series connection. However, the sensitivity saturation limits the single sensor SBP which, under 1 V, reaches the same level of 2000 MHz∙V/T as in a series connection. Above the single sensor breakdown voltage, linear sensitivity dependence on the bias and the constant 3 dB bandwidth of the series connection enable increasing its SBP up to nearly 10,000 MHz∙V/T under 5 V. Thus, although by tuning bias voltage it is possible to control the sensitivity-bandwidth product, the choice between the single TMR sensor and the series connection is crucial for the optimal performance in the high frequency range. Full article

(This article belongs to the Special Issue Magnetoresistive Sensors under Extreme Conditions)

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24 pages, 8079 KiB

Open AccessArticle

Novel Networked Remote Laboratory Architecture for Open Connectivity Based on PLC-OPC-LabVIEW-EJS Integration. Application in Remote Fuzzy Control and Sensors Data Acquisition

by Isaías González^1,*

, Antonio José Calderón¹

, Andrés Mejías²

and José Manuel Andújar²

¹ Department of Electrical Engineering, Electronics and Automation, University of Extremadura, Avenida de Elvas, s/n, Badajoz 06006, Spain

² Department of Electronic, Computer Science and Automation Engineering, University of Huelva, Escuela Técnica Superior, Crta. Huelva-Palos de la Fra, Palos de la Fra, Huelva 21919, Spain

Sensors 2016, 16(11), 1822; https://doi.org/10.3390/s16111822 - 31 Oct 2016

Cited by 33 | Viewed by 8897

Abstract

In this paper the design and implementation of a network for integrating Programmable Logic Controllers (PLC), the Object-Linking and Embedding for Process Control protocol (OPC) and the open-source Easy Java Simulations (EJS) package is presented. A LabVIEW interface and the Java-Internet-LabVIEW (JIL) server [...] Read more.

In this paper the design and implementation of a network for integrating Programmable Logic Controllers (PLC), the Object-Linking and Embedding for Process Control protocol (OPC) and the open-source Easy Java Simulations (EJS) package is presented. A LabVIEW interface and the Java-Internet-LabVIEW (JIL) server complete the scheme for data exchange. This configuration allows the user to remotely interact with the PLC. Such integration can be considered a novelty in scientific literature for remote control and sensor data acquisition of industrial plants. An experimental application devoted to remote laboratories is developed to demonstrate the feasibility and benefits of the proposed approach. The experiment to be conducted is the parameterization and supervision of a fuzzy controller of a DC servomotor. The graphical user interface has been developed with EJS and the fuzzy control is carried out by our own PLC. In fact, the distinctive features of the proposed novel network application are the integration of the OPC protocol to share information with the PLC and the application under control. The user can perform the tuning of the controller parameters online and observe in real time the effect on the servomotor behavior. The target group is engineering remote users, specifically in control- and automation-related tasks. The proposed architecture system is described and experimental results are presented. Full article

(This article belongs to the Section Physical Sensors)

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14 pages, 4895 KiB

Open AccessArticle

Fuzzy Neural Network-Based Interacting Multiple Model for Multi-Node Target Tracking Algorithm

by Baoliang Sun^*

, Chunlan Jiang and Ming Li

State Key Laboratory of Explosion Science and Technology, Beijing Institute of Technology, Beijing 100081, China

Sensors 2016, 16(11), 1823; https://doi.org/10.3390/s16111823 - 1 Nov 2016

Cited by 11 | Viewed by 5947

Abstract

An interacting multiple model for multi-node target tracking algorithm was proposed based on a fuzzy neural network (FNN) to solve the multi-node target tracking problem of wireless sensor networks (WSNs). Measured error variance was adaptively adjusted during the multiple model interacting output stage [...] Read more.

An interacting multiple model for multi-node target tracking algorithm was proposed based on a fuzzy neural network (FNN) to solve the multi-node target tracking problem of wireless sensor networks (WSNs). Measured error variance was adaptively adjusted during the multiple model interacting output stage using the difference between the theoretical and estimated values of the measured error covariance matrix. The FNN fusion system was established during multi-node fusion to integrate with the target state estimated data from different nodes and consequently obtain network target state estimation. The feasibility of the algorithm was verified based on a network of nine detection nodes. Experimental results indicated that the proposed algorithm could trace the maneuvering target effectively under sensor failure and unknown system measurement errors. The proposed algorithm exhibited great practicability in the multi-node target tracking of WSNs. Full article

(This article belongs to the Special Issue Scalable Localization in Wireless Sensor Networks)

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18 pages, 4571 KiB

Open AccessArticle

Millimetre Level Accuracy GNSS Positioning with the Blind Adaptive Beamforming Method in Interference Environments

by Saeed Daneshmand^*, Thyagaraja Marathe

and Gérard Lachapelle

Department of Geomatics Engineering, University of Calgary, PLAN Group Schulich School of Engineering, 2500 University Drive, N.W., Calgary, AB T2N 1N4, Canada

Sensors 2016, 16(11), 1824; https://doi.org/10.3390/s16111824 - 31 Oct 2016

Cited by 22 | Viewed by 6069

Abstract

The use of antenna arrays in Global Navigation Satellite System (GNSS) applications is gaining significant attention due to its superior capability to suppress both narrowband and wideband interference. However, the phase distortions resulting from array processing may limit the applicability of these methods [...] Read more.

The use of antenna arrays in Global Navigation Satellite System (GNSS) applications is gaining significant attention due to its superior capability to suppress both narrowband and wideband interference. However, the phase distortions resulting from array processing may limit the applicability of these methods for high precision applications using carrier phase based positioning techniques. This paper studies the phase distortions occurring with the adaptive blind beamforming method in which satellite angle of arrival (AoA) information is not employed in the optimization problem. To cater to non-stationary interference scenarios, the array weights of the adaptive beamformer are continuously updated. The effects of these continuous updates on the tracking parameters of a GNSS receiver are analyzed. The second part of this paper focuses on reducing the phase distortions during the blind beamforming process in order to allow the receiver to perform carrier phase based positioning by applying a constraint on the structure of the array configuration and by compensating the array uncertainties. Limitations of the previous methods are studied and a new method is proposed that keeps the simplicity of the blind beamformer structure and, at the same time, reduces tracking degradations while achieving millimetre level positioning accuracy in interference environments. To verify the applicability of the proposed method and analyze the degradations, array signals corresponding to the GPS L1 band are generated using a combination of hardware and software simulators. Furthermore, the amount of degradation and performance of the proposed method under different conditions are evaluated based on Monte Carlo simulations. Full article

(This article belongs to the Section Physical Sensors)

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24 pages, 9687 KiB

Open AccessArticle

An Integrated Wireless Wearable Sensor System for Posture Recognition and Indoor Localization

by Jian Huang¹

, Xiaoqiang Yu¹, Yuan Wang¹ and Xiling Xiao^2,*

¹ Key Laboratory of Image Processing and Intelligent Control, School of Automation, Huazhong University of Science and Technology, Wuhan 430074, China

² Department of Rehabilitation, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, 1277 Jiefang Avenue, Wuhan 430022, China

Sensors 2016, 16(11), 1825; https://doi.org/10.3390/s16111825 - 31 Oct 2016

Cited by 49 | Viewed by 7950

Abstract

In order to provide better monitoring for the elderly or patients, we developed an integrated wireless wearable sensor system that can realize posture recognition and indoor localization in real time. Five designed sensor nodes which are respectively fixed on lower limbs and a [...] Read more.

In order to provide better monitoring for the elderly or patients, we developed an integrated wireless wearable sensor system that can realize posture recognition and indoor localization in real time. Five designed sensor nodes which are respectively fixed on lower limbs and a standard Kalman filter are used to acquire basic attitude data. After the attitude angles of five body segments (two thighs, two shanks and the waist) are obtained, the pitch angles of the left thigh and waist are used to realize posture recognition. Based on all these attitude angles of body segments, we can also calculate the coordinates of six lower limb joints (two hip joints, two knee joints and two ankle joints). Then, a novel relative localization algorithm based on step length is proposed to realize the indoor localization of the user. Several sparsely distributed active Radio Frequency Identification (RFID) tags are used to correct the accumulative error in the relative localization algorithm and a set-membership filter is applied to realize the data fusion. The experimental results verify the effectiveness of the proposed algorithms. Full article

(This article belongs to the Special Issue Advances on Data Transmission and Analysis for Wearable Sensors Systems)

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17 pages, 5935 KiB

Open AccessArticle

New Flexible Silicone-Based EEG Dry Sensor Material Compositions Exhibiting Improvements in Lifespan, Conductivity, and Reliability

by Yi-Hsin Yu¹, Shih-Hsun Chen²

, Che-Lun Chang³, Chin-Teng Lin^4,*, W. David Hairston⁵ and Randy A. Mrozek⁶

¹ Department of Interactive Entertainment Design, China University of Technology, Taipei 11695, Taiwan

² Department of Mechanical Engineering, National Taiwan University of Science and Technology, Taipei 10607, Taiwan

³ Brain Research Center, National Chiao Tung University, Hsinchu 300, Taiwan

⁴ Faculty of Engineering and Information Technology, University of Technology, Sydney 2007, Australia

⁵ Translational Neuroscience Branch, Human Research and Engineering Directorate, U.S. Army Research Laboratory, Adelphi, MD 20783, USA

⁶ Macromolecular Science and Technology Branch, Weapons and Materials Research Directorate, U.S. Army Research Laboratory, Adelphi, MD 20783, USA

Sensors 2016, 16(11), 1826; https://doi.org/10.3390/s16111826 - 31 Oct 2016

Cited by 25 | Viewed by 7477

Abstract

This study investigates alternative material compositions for flexible silicone-based dry electroencephalography (EEG) electrodes to improve the performance lifespan while maintaining high-fidelity transmission of EEG signals. Electrode materials were fabricated with varying concentrations of silver-coated silica and silver flakes to evaluate their electrical, mechanical, [...] Read more.

This study investigates alternative material compositions for flexible silicone-based dry electroencephalography (EEG) electrodes to improve the performance lifespan while maintaining high-fidelity transmission of EEG signals. Electrode materials were fabricated with varying concentrations of silver-coated silica and silver flakes to evaluate their electrical, mechanical, and EEG transmission performance. Scanning electron microscope (SEM) analysis of the initial electrode development identified some weak points in the sensors’ construction, including particle pull-out and ablation of the silver coating on the silica filler. The newly-developed sensor materials achieved significant improvement in EEG measurements while maintaining the advantages of previous silicone-based electrodes, including flexibility and non-toxicity. The experimental results indicated that the proposed electrodes maintained suitable performance even after exposure to temperature fluctuations, 85% relative humidity, and enhanced corrosion conditions demonstrating improvements in the environmental stability. Fabricated flat (forehead) and acicular (hairy sites) electrodes composed of the optimum identified formulation exhibited low impedance and reliable EEG measurement; some initial human experiments demonstrate the feasibility of using these silicone-based electrodes for typical lab data collection applications. Full article

(This article belongs to the Section Biosensors)

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24 pages, 2309 KiB

Open AccessArticle

3D Buried Utility Location Using A Marching-Cross-Section Algorithm for Multi-Sensor Data Fusion

by Qingxu Dou^1,*, Lijun Wei¹, Derek R. Magee¹, Phil R. Atkins², David N. Chapman³, Giulio Curioni³, Kevin F. Goddard⁴, Farzad Hayati²

, Hugo Jenks⁵, Nicole Metje³

, Jennifer Muggleton⁶, Steve R. Pennock⁵, Emiliano Rustighi⁶

, Steven G. Swingler⁴, Christopher D. F. Rogers³ and Anthony G. Cohn¹

¹ School of Computing, University of Leeds, Leeds LS2 9JT, UK

² School of Electronic, Electrical and Computing Engineering, University of Birmingham, Birmingham B15 2TT, UK

³ School of Civil Engineering, University of Birmingham B15 2TT, UK

⁴ School of Electronics and Computer Science, University of Southampton, Southampton SO17 1BJ, UK

⁵ School of Electronic and Electrical Engineering, University of Bath, Bath BA2 7AY, UK

⁶ Institute of Sound and Vibration Research, University of Southampton, Southampton SO17 1BJ, UK

Sensors 2016, 16(11), 1827; https://doi.org/10.3390/s16111827 - 2 Nov 2016

Cited by 27 | Viewed by 8473

Abstract

We address the problem of accurately locating buried utility segments by fusing data from multiple sensors using a novel Marching-Cross-Section (MCS) algorithm. Five types of sensors are used in this work: Ground Penetrating Radar (GPR), Passive Magnetic Fields (PMF), Magnetic Gradiometer (MG), Low [...] Read more.

We address the problem of accurately locating buried utility segments by fusing data from multiple sensors using a novel Marching-Cross-Section (MCS) algorithm. Five types of sensors are used in this work: Ground Penetrating Radar (GPR), Passive Magnetic Fields (PMF), Magnetic Gradiometer (MG), Low Frequency Electromagnetic Fields (LFEM) and Vibro-Acoustics (VA). As part of the MCS algorithm, a novel formulation of the extended Kalman Filter (EKF) is proposed for marching existing utility tracks from a scan cross-section (scs) to the next one; novel rules for initializing utilities based on hypothesized detections on the first scs and for associating predicted utility tracks with hypothesized detections in the following scss are introduced. Algorithms are proposed for generating virtual scan lines based on given hypothesized detections when different sensors do not share common scan lines, or when only the coordinates of the hypothesized detections are provided without any information of the actual survey scan lines. The performance of the proposed system is evaluated with both synthetic data and real data. The experimental results in this work demonstrate that the proposed MCS algorithm can locate multiple buried utility segments simultaneously, including both straight and curved utilities, and can separate intersecting segments. By using the probabilities of a hypothesized detection being a pipe or a cable together with its 3D coordinates, the MCS algorithm is able to discriminate a pipe and a cable close to each other. The MCS algorithm can be used for both post- and on-site processing. When it is used on site, the detected tracks on the current scs can help to determine the location and direction of the next scan line. The proposed “multi-utility multi-sensor” system has no limit to the number of buried utilities or the number of sensors, and the more sensor data used, the more buried utility segments can be detected with more accurate location and orientation. Full article

(This article belongs to the Section Remote Sensors)

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18 pages, 1233 KiB

Open AccessArticle

A Cross-Correlational Analysis between Electroencephalographic and End-Tidal Carbon Dioxide Signals: Methodological Issues in the Presence of Missing Data and Real Data Results

by Maria Sole Morelli^1,2, Alberto Giannoni³, Claudio Passino^1,3, Luigi Landini^3,4, Michele Emdin^1,3 and Nicola Vanello^4,*

¹ Institute of Life Science, Scuola Superiore Sant’Anna, 56127 Pisa, Italy

² Research Center “E. Piaggio”, University of Pisa, 56122 Pisa, Italy

³ Fondazione Toscana Gabriele Monasterio, National Research Council, 56124 Pisa, Italy

⁴ Dipartimento di Ingegneria dell’Informazione, University of Pisa, 56124 Pisa, Italy

Sensors 2016, 16(11), 1828; https://doi.org/10.3390/s16111828 - 31 Oct 2016

Cited by 10 | Viewed by 4996

Abstract

Electroencephalographic (EEG) irreducible artifacts are common and the removal of corrupted segments from the analysis may be required. The present study aims at exploring the effects of different EEG Missing Data Segment (MDS) distributions on cross-correlation analysis, involving EEG and physiological signals. The [...] Read more.

Electroencephalographic (EEG) irreducible artifacts are common and the removal of corrupted segments from the analysis may be required. The present study aims at exploring the effects of different EEG Missing Data Segment (MDS) distributions on cross-correlation analysis, involving EEG and physiological signals. The reliability of cross-correlation analysis both at single subject and at group level as a function of missing data statistics was evaluated using dedicated simulations. Moreover, a Bayesian-based approach for combining the single subject results at group level by considering each subject’s reliability was introduced. Starting from the above considerations, the cross-correlation function between EEG Global Field Power (GFP) in delta band and end-tidal CO₂ (P_ETCO₂) during rest and voluntary breath-hold was evaluated in six healthy subjects. The analysis of simulated data results at single subject level revealed a worsening of precision and accuracy in the cross-correlation analysis in the presence of MDS. At the group level, a large improvement in the results’ reliability with respect to single subject analysis was observed. The proposed Bayesian approach showed a slight improvement with respect to simple average results. Real data results were discussed in light of the simulated data tests and of the current physiological findings. Full article

(This article belongs to the Special Issue Noninvasive Biomedical Sensors)

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11 pages, 3352 KiB

Open AccessArticle

Microwave Chemical Sensor Using Substrate-Integrated-Waveguide Cavity

by Muhammad Usman Memon

and Sungjoon Lim^*

School of Electrical and Electronics Engineering, Chung-Ang University, 84 Heukseok-ro, Dongjak-gu, Seoul 156-756, Korea

Sensors 2016, 16(11), 1829; https://doi.org/10.3390/s16111829 - 31 Oct 2016

Cited by 38 | Viewed by 8630 | Correction

Abstract

This research proposes a substrate-integrated waveguide (SIW) cavity sensor to detect several chemicals using the microwave frequency range. The frequency response of the presented SIW sensor is switched by filling a very small quantity of chemical inside of the fluidic channel, which also [...] Read more.

This research proposes a substrate-integrated waveguide (SIW) cavity sensor to detect several chemicals using the microwave frequency range. The frequency response of the presented SIW sensor is switched by filling a very small quantity of chemical inside of the fluidic channel, which also causes a difference in the effective permittivity. The fluidic channel on this structure is either empty or filled with a chemical; when it is empty the structure resonates at 17.08 GHz. There is always a different resonant frequency when any chemical is injected into the fluidic channel. The maximum amount of chemical after injection is held in the center of the SIW structure, which has the maximum magnitude of the electric field distribution. Thus, the objective of sensing chemicals in this research is achieved by perturbing the electric fields of the SIW structure. Full article

(This article belongs to the Special Issue Non-Contact Sensing)

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13 pages, 5892 KiB

Open AccessArticle

Gas Sensing Analysis of Ag-Decorated Graphene for Sulfur Hexafluoride Decomposition Products Based on the Density Functional Theory

by Xiaoxing Zhang^1,2,*, Rong Huang¹, Yingang Gui¹ and Hong Zeng³

¹ State Key Laboratory of Power Transmission Equipment & System Security and New Technology, Chongqing University, Chongqing 400044, China

² School of Electrical Engineering, Wuhan University, Wuhan 430072, China

³ No. 1 Branch of Chongqing Academy of Metrology and Quality Inspection, Chongqing 402260, China

Sensors 2016, 16(11), 1830; https://doi.org/10.3390/s16111830 - 1 Nov 2016

Cited by 30 | Viewed by 7975

Abstract

Detection of decomposition products of sulfur hexafluoride (SF₆) is one of the best ways to diagnose early latent insulation faults in gas-insulated equipment, and the occurrence of sudden accidents can be avoided effectively by finding early latent faults. Recently, functionalized graphene, [...] Read more.

Detection of decomposition products of sulfur hexafluoride (SF₆) is one of the best ways to diagnose early latent insulation faults in gas-insulated equipment, and the occurrence of sudden accidents can be avoided effectively by finding early latent faults. Recently, functionalized graphene, a kind of gas sensing material, has been reported to show good application prospects in the gas sensor field. Therefore, calculations were performed to analyze the gas sensing properties of intrinsic graphene (Int-graphene) and functionalized graphene-based material, Ag-decorated graphene (Ag-graphene), for decomposition products of SF₆, including SO₂F₂, SOF₂, and SO₂, based on density functional theory (DFT). We thoroughly investigated a series of parameters presenting gas-sensing properties of adsorbing process about gas molecule (SO₂F₂, SOF₂, SO₂) and double gas molecules (2SO₂F₂, 2SOF₂, 2SO₂) on Ag-graphene, including adsorption energy, net charge transfer, electronic state density, and the highest and lowest unoccupied molecular orbital. The results showed that the Ag atom significantly enhances the electrochemical reactivity of graphene, reflected in the change of conductivity during the adsorption process. SO₂F₂ and SO₂ gas molecules on Ag-graphene presented chemisorption, and the adsorption strength was SO₂F₂ > SO₂, while SOF₂ absorption on Ag-graphene was physical adsorption. Thus, we concluded that Ag-graphene showed good selectivity and high sensitivity to SO₂F₂. The results can provide a helpful guide in exploring Ag-graphene material in experiments for monitoring the insulation status of SF₆-insulated equipment based on detecting decomposition products of SF₆. Full article

(This article belongs to the Special Issue The Use of New and/or Improved Materials for Sensing Applications)

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0 pages, 144 KiB

Open AccessRetraction

RETRACTED: Jafer et al. Design of New Power Management Circuit for Light Energy Harvesting System. Sensors 2016, 16, 270

by Sensors Editorial Office

MDPI AG, St. Alban-Anlage 66, 4052 Basel, Switzerland

Sensors 2016, 16(11), 1831; https://doi.org/10.3390/s16111831 - 31 Oct 2016

Viewed by 3952

Abstract

We have recently discovered that the majority of the text and ﬁgures in the title paper [1] is copied from a previously published thesis [2].[...] Full article

16 pages, 4334 KiB

Open AccessArticle

Estimation of Anonymous Email Network Characteristics through Statistical Disclosure Attacks

by Javier Portela¹, Luis Javier García Villalba^1,*

, Alejandra Guadalupe Silva Trujillo¹

, Ana Lucila Sandoval Orozco¹ and Tai-Hoon Kim²

¹ Group of Analysis, Security and Systems (GASS), Department of Software Engineering and Artificial Intelligence (DISIA), Faculty of Information Technology and Computer Science, Office 431, Universidad Complutense de Madrid (UCM), Calle Profesor José García Santesmases, 9, Ciudad Universitaria, Madrid 28040, Spain

² Department of Convergence Security, Sungshin Women’s University, 249-1 Dongseon-dong 3-ga, Seoul 136-742, Korea

Sensors 2016, 16(11), 1832; https://doi.org/10.3390/s16111832 - 1 Nov 2016

Cited by 6 | Viewed by 5583

Abstract

Social network analysis aims to obtain relational data from social systems to identify leaders, roles, and communities in order to model profiles or predict a specific behavior in users’ network. Preserving anonymity in social networks is a subject of major concern. Anonymity can [...] Read more.

Social network analysis aims to obtain relational data from social systems to identify leaders, roles, and communities in order to model profiles or predict a specific behavior in users’ network. Preserving anonymity in social networks is a subject of major concern. Anonymity can be compromised by disclosing senders’ or receivers’ identity, message content, or sender-receiver relationships. Under strongly incomplete information, a statistical disclosure attack is used to estimate the network and node characteristics such as centrality and clustering measures, degree distribution, and small-world-ness. A database of email networks in 29 university faculties is used to study the method. A research on the small-world-ness and Power law characteristics of these email networks is also developed, helping to understand the behavior of small email networks. Full article

(This article belongs to the Special Issue Topology Control in Emerging Sensor Networks)

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12 pages, 3398 KiB

Open AccessArticle

Flexible Graphene Electrodes for Prolonged Dynamic ECG Monitoring

by Cunguang Lou¹

, Ruikai Li¹, Zhaopeng Li¹, Tie Liang¹, Zihui Wei², Mingtao Run³, Xiaobing Yan⁴ and Xiuling Liu^1,*

¹ Department of Biomedical Engineering, College of Electronic Information Engineering & Key Laboratory of Digital Medical Engineering of Hebei Province, Hebei University, Baoding 071002, China

² College of Quality and Technical Supervision, Hebei University, Baoding 071002, China

³ College of Chemistry & Environment Science, Hebei University, Baoding 071002, China

⁴ Department of Electronic Science and Technology, College of Electronic Information Engineering & Key Laboratory of Digital Medical Engineering of Hebei province, Hebei University, Baoding 071002, China

Sensors 2016, 16(11), 1833; https://doi.org/10.3390/s16111833 - 1 Nov 2016

Cited by 115 | Viewed by 14543

Abstract

This paper describes the development of a graphene-based dry flexible electrocardiography (ECG) electrode and a portable wireless ECG measurement system. First, graphene films on polyethylene terephthalate (PET) substrates and graphene paper were used to construct the ECG electrode. Then, a graphene textile was [...] Read more.

This paper describes the development of a graphene-based dry flexible electrocardiography (ECG) electrode and a portable wireless ECG measurement system. First, graphene films on polyethylene terephthalate (PET) substrates and graphene paper were used to construct the ECG electrode. Then, a graphene textile was synthesized for the fabrication of a wearable ECG monitoring system. The structure and the electrical properties of the graphene electrodes were evaluated using Raman spectroscopy, scanning electron microscopy (SEM), and alternating current impedance spectroscopy. ECG signals were then collected from healthy subjects using the developed graphene electrode and portable measurement system. The results show that the graphene electrode was able to acquire the typical characteristics and features of human ECG signals with a high signal-to-noise (SNR) ratio in different states of motion. A week-long continuous wearability test showed no degradation in the ECG signal quality over time. The graphene-based flexible electrode demonstrates comfortability, good biocompatibility, and high electrophysiological detection sensitivity. The graphene electrode also combines the potential for use in long-term wearable dynamic cardiac activity monitoring systems with convenience and comfort for use in home health care of elderly and high-risk adults. Full article

(This article belongs to the Special Issue Body Worn Behavior Sensing)

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27 pages, 578 KiB

Open AccessArticle

Design and Analysis of A Beacon-Less Routing Protocol for Large Volume Content Dissemination in Vehicular Ad Hoc Networks

by Miao Hu¹, Zhangdui Zhong^1,†, Minming Ni^1,*,† and Andrea Baiocchi^2,†

¹ State Key Laboratory of Rail Traffic Control and Safety, Beijing Jiaotong University, Beijing 100044, China

² Department of Information Engineering, Electronics and Telecommunications (DIET), University of Roma Sapienza, Roma 00184, Italy

^† These authors contributed equally to this work.

Sensors 2016, 16(11), 1834; https://doi.org/10.3390/s16111834 - 1 Nov 2016

Cited by 14 | Viewed by 4799

Abstract

Large volume content dissemination is pursued by the growing number of high quality applications for Vehicular Ad hoc NETworks(VANETs), e.g., the live road surveillance service and the video-based overtaking assistant service. For the highly dynamical vehicular network topology, beacon-less routing protocols have been [...] Read more.

Large volume content dissemination is pursued by the growing number of high quality applications for Vehicular Ad hoc NETworks(VANETs), e.g., the live road surveillance service and the video-based overtaking assistant service. For the highly dynamical vehicular network topology, beacon-less routing protocols have been proven to be efficient in achieving a balance between the system performance and the control overhead. However, to the authors’ best knowledge, the routing design for large volume content has not been well considered in the previous work, which will introduce new challenges, e.g., the enhanced connectivity requirement for a radio link. In this paper, a link Lifetime-aware Beacon-less Routing Protocol (LBRP) is designed for large volume content delivery in VANETs. Each vehicle makes the forwarding decision based on the message header information and its current state, including the speed and position information. A semi-Markov process analytical model is proposed to evaluate the expected delay in constructing one routing path for LBRP. Simulations show that the proposed LBRP scheme outperforms the traditional dissemination protocols in providing a low end-to-end delay. The analytical model is shown to exhibit a good match on the delay estimation with Monte Carlo simulations, as well. Full article

(This article belongs to the Special Issue Vehicular Sensor Networks: Technical Challenges, Supports, and Application Experiences)

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25 pages, 2024 KiB

Open AccessArticle

Multi-Sensor Fusion with Interaction Multiple Model and Chi-Square Test Tolerant Filter

by Chun Yang^1,‡

, Arash Mohammadi^2,*,†,‡

and Qing-Wei Chen¹

¹ College of Automation, Nanjing University of Science and Technology, Nanjing 210094, China

² Concordia Institute for Information System Engineering, Concordia University, Montreal, QC H3G-1M8, Canada

^† Current address: 1455 De Maisonneuve Blvd. W. EV-009.187, Montreal, QC HG-1M8, Canada

^‡ These authors contributed equally to this work.

Sensors 2016, 16(11), 1835; https://doi.org/10.3390/s16111835 - 2 Nov 2016

Cited by 42 | Viewed by 7618

Abstract

Motivated by the key importance of multi-sensor information fusion algorithms in the state-of-the-art integrated navigation systems due to recent advancements in sensor technologies, telecommunication, and navigation systems, the paper proposes an improved and innovative fault-tolerant fusion framework. An integrated navigation system is considered [...] Read more.

Motivated by the key importance of multi-sensor information fusion algorithms in the state-of-the-art integrated navigation systems due to recent advancements in sensor technologies, telecommunication, and navigation systems, the paper proposes an improved and innovative fault-tolerant fusion framework. An integrated navigation system is considered consisting of four sensory sub-systems, i.e., Strap-down Inertial Navigation System (SINS), Global Navigation System (GPS), the Bei-Dou2 (BD2) and Celestial Navigation System (CNS) navigation sensors. In such multi-sensor applications, on the one hand, the design of an efficient fusion methodology is extremely constrained specially when no information regarding the system’s error characteristics is available. On the other hand, the development of an accurate fault detection and integrity monitoring solution is both challenging and critical. The paper addresses the sensitivity issues of conventional fault detection solutions and the unavailability of a precisely known system model by jointly designing fault detection and information fusion algorithms. In particular, by using ideas from Interacting Multiple Model (IMM) filters, the uncertainty of the system will be adjusted adaptively by model probabilities and using the proposed fuzzy-based fusion framework. The paper also addresses the problem of using corrupted measurements for fault detection purposes by designing a two state propagator chi-square test jointly with the fusion algorithm. Two IMM predictors, running in parallel, are used and alternatively reactivated based on the received information form the fusion filter to increase the reliability and accuracy of the proposed detection solution. With the combination of the IMM and the proposed fusion method, we increase the failure sensitivity of the detection system and, thereby, significantly increase the overall reliability and accuracy of the integrated navigation system. Simulation results indicate that the proposed fault tolerant fusion framework provides superior performance over its traditional counterparts. Full article

(This article belongs to the Special Issue Advances in Multi-Sensor Information Fusion: Theory and Applications)

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16 pages, 3738 KiB

Open AccessArticle

Machine Learning Based Single-Frame Super-Resolution Processing for Lensless Blood Cell Counting

by Xiwei Huang^1,2

, Yu Jiang³, Xu Liu³, Hang Xu³, Zhi Han², Hailong Rong², Haiping Yang², Mei Yan^2,* and Hao Yu^3,*

¹ Ministry of Education Key Lab of RF Circuits and Systems, Hangzhou Dianzi University, Hangzhou 310018, China

² School of Microelectronics, Southeast University, Wuxi 214135, China

³ School of Electrical and Electronic Engineering, Nanyang Technological University, Singapore 639798, Singapore

Sensors 2016, 16(11), 1836; https://doi.org/10.3390/s16111836 - 2 Nov 2016

Cited by 57 | Viewed by 10231

Abstract

A lensless blood cell counting system integrating microfluidic channel and a complementary metal oxide semiconductor (CMOS) image sensor is a promising technique to miniaturize the conventional optical lens based imaging system for point-of-care testing (POCT). However, such a system has limited resolution, making [...] Read more.

A lensless blood cell counting system integrating microfluidic channel and a complementary metal oxide semiconductor (CMOS) image sensor is a promising technique to miniaturize the conventional optical lens based imaging system for point-of-care testing (POCT). However, such a system has limited resolution, making it imperative to improve resolution from the system-level using super-resolution (SR) processing. Yet, how to improve resolution towards better cell detection and recognition with low cost of processing resources and without degrading system throughput is still a challenge. In this article, two machine learning based single-frame SR processing types are proposed and compared for lensless blood cell counting, namely the Extreme Learning Machine based SR (ELMSR) and Convolutional Neural Network based SR (CNNSR). Moreover, lensless blood cell counting prototypes using commercial CMOS image sensors and custom designed backside-illuminated CMOS image sensors are demonstrated with ELMSR and CNNSR. When one captured low-resolution lensless cell image is input, an improved high-resolution cell image will be output. The experimental results show that the cell resolution is improved by 4×, and CNNSR has 9.5% improvement over the ELMSR on resolution enhancing performance. The cell counting results also match well with a commercial flow cytometer. Such ELMSR and CNNSR therefore have the potential for efficient resolution improvement in lensless blood cell counting systems towards POCT applications. Full article

(This article belongs to the Special Issue Microfluidics-Based Microsystem Integration Research)

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18 pages, 7546 KiB

Open AccessArticle

Feature Mining and Health Assessment for Gearboxes Using Run-Up/Coast-Down Signals

by Ming Zhao¹

, Jing Lin^2,*, Yonghao Miao¹ and Xiaoqiang Xu¹

¹ School of Mechanical Engineering, Xi’an Jiaotong University, Xi’an 710049, China

² State Key Laboratory for Manufacturing Systems Engineering, Xi’an Jiaotong University, Xi’an 710049, China

Sensors 2016, 16(11), 1837; https://doi.org/10.3390/s16111837 - 2 Nov 2016

Cited by 20 | Viewed by 6498

Abstract

Vibration signals measured in the run-up/coast-down (R/C) processes usually carry rich information about the health status of machinery. However, a major challenge in R/C signals analysis lies in how to exploit more diagnostic information, and how this information could be properly integrated to [...] Read more.

Vibration signals measured in the run-up/coast-down (R/C) processes usually carry rich information about the health status of machinery. However, a major challenge in R/C signals analysis lies in how to exploit more diagnostic information, and how this information could be properly integrated to achieve a more reliable maintenance decision. Aiming at this problem, a framework of R/C signals analysis is presented for the health assessment of gearbox. In the proposed methodology, we first investigate the data preprocessing and feature selection issues for R/C signals. Based on that, a sparsity-guided feature enhancement scheme is then proposed to extract the weak phase jitter associated with gear defect. In order for an effective feature mining and integration under R/C, a generalized phase demodulation technique is further established to reveal the evolution of modulation feature with operating speed and rotation angle. The experimental results indicate that the proposed methodology could not only detect the presence of gear damage, but also offer a novel insight into the dynamic behavior of gearbox. Full article

(This article belongs to the Section Physical Sensors)

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14 pages, 14025 KiB

Open AccessArticle

An Analysis of the Influence of Flight Parameters in the Generation of Unmanned Aerial Vehicle (UAV) Orthomosaicks to Survey Archaeological Areas

by Francisco-Javier Mesas-Carrascosa^*

, María Dolores Notario García, Jose Emilio Meroño de Larriva

and Alfonso García-Ferrer

Department of Graphic Engineering and Geomatics, University of Cordoba, Campus de Rabanales, Córdoba 14071, Spain

Sensors 2016, 16(11), 1838; https://doi.org/10.3390/s16111838 - 1 Nov 2016

Cited by 95 | Viewed by 9799

Abstract

This article describes the configuration and technical specifications of a multi-rotor unmanned aerial vehicle (UAV) using a red–green–blue (RGB) sensor for the acquisition of images needed for the production of orthomosaics to be used in archaeological applications. Several flight missions were programmed as [...] Read more.

This article describes the configuration and technical specifications of a multi-rotor unmanned aerial vehicle (UAV) using a red–green–blue (RGB) sensor for the acquisition of images needed for the production of orthomosaics to be used in archaeological applications. Several flight missions were programmed as follows: flight altitudes at 30, 40, 50, 60, 70 and 80 m above ground level; two forward and side overlap settings (80%–50% and 70%–40%); and the use, or lack thereof, of ground control points. These settings were chosen to analyze their influence on the spatial quality of orthomosaicked images processed by Inpho UASMaster (Trimble, CA, USA). Changes in illumination over the study area, its impact on flight duration, and how it relates to these settings is also considered. The combined effect of these parameters on spatial quality is presented as well, defining a ratio between ground sample distance of UAV images and expected root mean square of a UAV orthomosaick. The results indicate that a balance between all the proposed parameters is useful for optimizing mission planning and image processing, altitude above ground level (AGL) being main parameter because of its influence on root mean square error (RMSE). Full article

(This article belongs to the Special Issue UAV-Based Remote Sensing)

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9 pages, 3997 KiB

Open AccessArticle

A Stretchable Radio-Frequency Strain Sensor Using Screen Printing Technology

by Heijun Jeong and Sungjoon Lim^*

School of Electrical and Electronics Engineering, College of Engineering, Chung-Ang University, 221 Heukseok-dong, Dongjak-gu, Seoul 156-756, Korea

Sensors 2016, 16(11), 1839; https://doi.org/10.3390/s16111839 - 2 Nov 2016

Cited by 22 | Viewed by 5916

Abstract

In this paper, we propose a stretchable radio-frequency (RF) strain sensor fabricated with screen printing technology. The RF sensor is designed using a half-wavelength patch that resonates at 3.7 GHz. The resonant frequency is determined by the length of the patch, and it [...] Read more.

In this paper, we propose a stretchable radio-frequency (RF) strain sensor fabricated with screen printing technology. The RF sensor is designed using a half-wavelength patch that resonates at 3.7 GHz. The resonant frequency is determined by the length of the patch, and it therefore changes when the patch is stretched. Polydimethylsiloxane (PDMS) is used to create the substrate, because of its stretchable and screen-printable surface. In addition, Dupont PE872 (Dupont, NC, American) silver conductive ink is used to create the stretchable conductive patterns. The sensor performance is demonstrated both with full-wave simulations and with measurements carried out on a fabricated sample. When the length of the patch sensor is increased by a 7.8% stretch, the resonant frequency decreases from 3.7 GHz to 3.43 GHz, evidencing a sensitivity of 3.43 × 10⁷ Hz/%. Stretching the patch along its width does not change the resonant frequency. Full article

(This article belongs to the Section Physical Sensors)

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14 pages, 1952 KiB

Open AccessArticle

Complex IoT Systems as Enablers for Smart Homes in a Smart City Vision

by Per Lynggaard^* and Knud Erik Skouby

Center for Communication and Information Technologies Aalborg University Denmark; A. C. Meyers Vænge 15, 2450 Copenhagen SV, Denmark

Sensors 2016, 16(11), 1840; https://doi.org/10.3390/s16111840 - 2 Nov 2016

Cited by 40 | Viewed by 9648

Abstract

The world is entering a new era, where Internet-of-Things (IoT), smart homes, and smart cities will play an important role in meeting the so-called big challenges. In the near future, it is foreseen that the majority of the world’s population will live their [...] Read more.

The world is entering a new era, where Internet-of-Things (IoT), smart homes, and smart cities will play an important role in meeting the so-called big challenges. In the near future, it is foreseen that the majority of the world’s population will live their lives in smart homes and in smart cities. To deal with these challenges, to support a sustainable urban development, and to improve the quality of life for citizens, a multi-disciplinary approach is needed. It seems evident, however, that a new, advanced Information and Communications Technology ICT infrastructure is a key feature to realize the “smart” vision. This paper proposes a specific solution in the form of a hierarchical layered ICT based infrastructure that handles ICT issues related to the “big challenges” and seamlessly integrates IoT, smart homes, and smart city structures into one coherent unit. To exemplify benefits of this infrastructure, a complex IoT system has been deployed, simulated and elaborated. This simulation deals with wastewater energy harvesting from smart buildings located in a smart city context. From the simulations, it has been found that the proposed infrastructure is able to harvest between 50% and 75% of the wastewater energy in a smart residential building. By letting the smart city infrastructure coordinate and control the harvest time and duration, it is possible to achieve considerable energy savings in the smart homes, and it is possible to reduce the peak-load for district heating plants. Full article

(This article belongs to the Special Issue Smart City: Vision and Reality)

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10 pages, 5820 KiB

Open AccessReview

Optical Microbottle Resonators for Sensing

by Pablo Bianucci

Department of Physics, Concordia University, Montral, QC H4B 1R6, Canada

Sensors 2016, 16(11), 1841; https://doi.org/10.3390/s16111841 - 2 Nov 2016

Cited by 54 | Viewed by 8713

Abstract

Whispering gallery mode (WGM) optical microresonators have been shown to be the basis for sensors able to detect minute changes in their environment. This has made them a well-established platform for highly sensitive physical, chemical, and biological sensors. Microbottle resonators (MBR) are a [...] Read more.

Whispering gallery mode (WGM) optical microresonators have been shown to be the basis for sensors able to detect minute changes in their environment. This has made them a well-established platform for highly sensitive physical, chemical, and biological sensors. Microbottle resonators (MBR) are a type of WGM optical microresonator. They share characteristics with other, more established, resonator geometries such as cylinders and spheres, while presenting their unique spectral signature and other distinguishing features. In this review, we discuss recent advances in the theory and fabrication of different kinds of MBRs, including hollow ones, and their application to optofluidic sensing. Full article

(This article belongs to the Special Issue Label-Free Optical Biosensors)

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25 pages, 8728 KiB

Open AccessArticle

Pixel-Level and Robust Vibration Source Sensing in High-Frame-Rate Video Analysis

by Mingjun Jiang^*

, Tadayoshi Aoyama, Takeshi Takaki and Idaku Ishii

Department of System Cybernetics, Hiroshima University, 1-4-1 Kagamiyama, Higashi-Hiroshima, Hiroshima 739-8527, Japan

Sensors 2016, 16(11), 1842; https://doi.org/10.3390/s16111842 - 2 Nov 2016

Cited by 21 | Viewed by 7050

Abstract

We investigate the effect of appearance variations on the detectability of vibration feature extraction with pixel-level digital filters for high-frame-rate videos. In particular, we consider robust vibrating object tracking, which is clearly different from conventional appearance-based object tracking with spatial pattern recognition in [...] Read more.

We investigate the effect of appearance variations on the detectability of vibration feature extraction with pixel-level digital filters for high-frame-rate videos. In particular, we consider robust vibrating object tracking, which is clearly different from conventional appearance-based object tracking with spatial pattern recognition in a high-quality image region of a certain size. For 512 × 512 videos of a rotating fan located at different positions and orientations and captured at 2000 frames per second with different lens settings, we verify how many pixels are extracted as vibrating regions with pixel-level digital filters. The effectiveness of dynamics-based vibration features is demonstrated by examining the robustness against changes in aperture size and the focal condition of the camera lens, the apparent size and orientation of the object being tracked, and its rotational frequency, as well as complexities and movements of background scenes. Tracking experiments for a flying multicopter with rotating propellers are also described to verify the robustness of localization under complex imaging conditions in outside scenarios. Full article

(This article belongs to the Special Issue Vision-Based Sensors in Field Robotics)

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20 pages, 7548 KiB

Open AccessArticle

Microwave Moisture Sensing of Seedcotton: Part 1: Seedcotton Microwave Material Properties

by Mathew G. Pelletier^*

, John D. Wanjura

and Greg A. Holt

United States Department of Agriculture, Agricultural Research Services; Cotton Production & Processing Research Unit, Lubbock, TX 79403, USA

Sensors 2016, 16(11), 1843; https://doi.org/10.3390/s16111843 - 2 Nov 2016

Cited by 6 | Viewed by 4655

Abstract

Moisture content at harvest is a key parameter that impacts quality and how well the cotton crop can be stored without degrading before processing. It is also a key parameter of interest for harvest time field trials as it can directly influence the [...] Read more.

Moisture content at harvest is a key parameter that impacts quality and how well the cotton crop can be stored without degrading before processing. It is also a key parameter of interest for harvest time field trials as it can directly influence the quality of the harvested crop as well as skew the results of in-field yield and quality assessments. Microwave sensing of moisture has several unique advantages over lower frequency sensing approaches. The first is that microwaves are insensitive to variations in conductivity, due to presence of salts or minerals. The second advantage is that microwaves can peer deep inside large bulk packaging to assess the internal moisture content without performing a destructive tear down of the package. To help facilitate the development of a microwave moisture sensor for seedcotton; research was performed to determine the basic microwave properties of seedcotton. The research was performed on 110 kg micro-modules, which are of direct interest to research teams for use in ongoing field-based research projects. It should also prove useful for the enhancement of existing and future yield monitor designs. Experimental data was gathered on the basic relations between microwave material properties and seedcotton over the range from 1.0 GHz to 2.5 GHz and is reported on herein. This research is part one of a two-part series that reports on the fundamental microwave properties of seedcotton as moisture and density vary naturally during the course of typical harvesting operations; part two will utilize this data to formulate a prediction algorithm to form the basis for a prototype microwave moisture sensor. Full article

(This article belongs to the Section Physical Sensors)

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13 pages, 7915 KiB

Open AccessArticle

Towards Autonomous Modular UAV Missions: The Detection, Geo-Location and Landing Paradigm

by Sarantis Kyristsis¹, Angelos Antonopoulos², Theofilos Chanialakis², Emmanouel Stefanakis², Christos Linardos¹, Achilles Tripolitsiotis^1,3 and Panagiotis Partsinevelos^1,4,*

¹ School of Mineral Resources Engineering, Technical University of Crete, Chania 73100, Greece

² School of Electrical and Computer Engineering, Technical University of Crete, Chania 73100, Greece

³ Space Geomatica Ltd., Chania 73133, Greece

⁴ School of Mineral Resources Engineering, Laboratory of Geodesy and Geomatics Engineering, SenseLAB Research Group, Chania 73100, Greece

Sensors 2016, 16(11), 1844; https://doi.org/10.3390/s16111844 - 3 Nov 2016

Cited by 42 | Viewed by 10792

Abstract

Nowadays, various unmanned aerial vehicle (UAV) applications become increasingly demanding since they require real-time, autonomous and intelligent functions. Towards this end, in the present study, a fully autonomous UAV scenario is implemented, including the tasks of area scanning, target recognition, geo-location, monitoring, following [...] Read more.

Nowadays, various unmanned aerial vehicle (UAV) applications become increasingly demanding since they require real-time, autonomous and intelligent functions. Towards this end, in the present study, a fully autonomous UAV scenario is implemented, including the tasks of area scanning, target recognition, geo-location, monitoring, following and finally landing on a high speed moving platform. The underlying methodology includes AprilTag target identification through Graphics Processing Unit (GPU) parallelized processing, image processing and several optimized locations and approach algorithms employing gimbal movement, Global Navigation Satellite System (GNSS) readings and UAV navigation. For the experimentation, a commercial and a custom made quad-copter prototype were used, portraying a high and a low-computational embedded platform alternative. Among the successful targeting and follow procedures, it is shown that the landing approach can be successfully performed even under high platform speeds. Full article

(This article belongs to the Special Issue UAV-Based Remote Sensing)

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18 pages, 819 KiB

Open AccessArticle

RSS Fingerprint Based Indoor Localization Using Sparse Representation with Spatio-Temporal Constraint

by Xinglin Piao¹, Yong Zhang¹, Tingshu Li¹, Yongli Hu^1,*

, Hao Liu², Ke Zhang³ and Yun Ge¹

¹ Beijing Advanced Innovation Center for Future Internet Technology, Beijing Key Laboratory of Multimedia and Intelligent Software Technology, Beijing University of Technology, Beijing 100124, China

² Beijing Transportation Information Center, Beijing 100073, China

³ Beijing Transportation Coordination Center, Beijing 100073, China

Sensors 2016, 16(11), 1845; https://doi.org/10.3390/s16111845 - 3 Nov 2016

Cited by 4 | Viewed by 5123

Abstract

The Received Signal Strength (RSS) fingerprint-based indoor localization is an important research topic in wireless network communications. Most current RSS fingerprint-based indoor localization methods do not explore and utilize the spatial or temporal correlation existing in fingerprint data and measurement data, which is [...] Read more.

The Received Signal Strength (RSS) fingerprint-based indoor localization is an important research topic in wireless network communications. Most current RSS fingerprint-based indoor localization methods do not explore and utilize the spatial or temporal correlation existing in fingerprint data and measurement data, which is helpful for improving localization accuracy. In this paper, we propose an RSS fingerprint-based indoor localization method by integrating the spatio-temporal constraints into the sparse representation model. The proposed model utilizes the inherent spatial correlation of fingerprint data in the fingerprint matching and uses the temporal continuity of the RSS measurement data in the localization phase. Experiments on the simulated data and the localization tests in the real scenes show that the proposed method improves the localization accuracy and stability effectively compared with state-of-the-art indoor localization methods. Full article

(This article belongs to the Section Sensor Networks)

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25 pages, 1299 KiB

Open AccessArticle

An Effective Massive Sensor Network Data Access Scheme Based on Topology Control for the Internet of Things

by Meng Yi, Qingkui Chen^* and Neal N. Xiong

University of Shanghai for Science and Technology, Shanghai 200093, China

Sensors 2016, 16(11), 1846; https://doi.org/10.3390/s16111846 - 3 Nov 2016

Cited by 7 | Viewed by 6092

Abstract

This paper considers the distributed access and control problem of massive wireless sensor networks’ data access center for the Internet of Things, which is an extension of wireless sensor networks and an element of its topology structure. In the context of the arrival [...] Read more.

This paper considers the distributed access and control problem of massive wireless sensor networks’ data access center for the Internet of Things, which is an extension of wireless sensor networks and an element of its topology structure. In the context of the arrival of massive service access requests at a virtual data center, this paper designs a massive sensing data access and control mechanism to improve the access efficiency of service requests and makes full use of the available resources at the data access center for the Internet of things. Firstly, this paper proposes a synergistically distributed buffer access model, which separates the information of resource and location. Secondly, the paper divides the service access requests into multiple virtual groups based on their characteristics and locations using an optimized self-organizing feature map neural network. Furthermore, this paper designs an optimal scheduling algorithm of group migration based on the combination scheme between the artificial bee colony algorithm and chaos searching theory. Finally, the experimental results demonstrate that this mechanism outperforms the existing schemes in terms of enhancing the accessibility of service requests effectively, reducing network delay, and has higher load balancing capacity and higher resource utility rate. Full article

(This article belongs to the Special Issue Topology Control in Emerging Sensor Networks)

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15 pages, 3337 KiB

Open AccessArticle

Wearable IMU for Shoulder Injury Prevention in Overhead Sports

by Samir A. Rawashdeh^1,*, Derek A. Rafeldt² and Timothy L. Uhl²

¹ Electrical and Computer Engineering, University of Michigan, Dearborn, MI 48128, USA

² Athletic Training and Rehabilitation Sciences, University of Kentucky, Lexington, KY 40536-0200, USA

Sensors 2016, 16(11), 1847; https://doi.org/10.3390/s16111847 - 3 Nov 2016

Cited by 68 | Viewed by 15264

Abstract

Body-worn inertial sensors have enabled motion capture outside of the laboratory setting. In this work, an inertial measurement unit was attached to the upper arm to track and discriminate between shoulder motion gestures in order to help prevent shoulder over-use injuries in athletics [...] Read more.

Body-worn inertial sensors have enabled motion capture outside of the laboratory setting. In this work, an inertial measurement unit was attached to the upper arm to track and discriminate between shoulder motion gestures in order to help prevent shoulder over-use injuries in athletics through real-time preventative feedback. We present a detection and classification approach that can be used to count the number of times certain motion gestures occur. The application presented involves tracking baseball throws and volleyball serves, which are common overhead movements that can lead to shoulder and elbow overuse injuries. Eleven subjects are recruited to collect training, testing, and randomized validation data, which include throws, serves, and seven other exercises that serve as a large null class of similar movements, which is analogous to a realistic usage scenario and requires a robust estimator. Full article

(This article belongs to the Collection Sensors for Globalized Healthy Living and Wellbeing)

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28 pages, 49792 KiB

Open AccessArticle

Dicotyledon Weed Quantification Algorithm for Selective Herbicide Application in Maize Crops

by Morten Stigaard Laursen^1,*

, Rasmus Nyholm Jørgensen¹

, Henrik Skov Midtiby²

, Kjeld Jensen²

, Martin Peter Christiansen³, Thomas Mosgaard Giselsson⁴, Anders Krogh Mortensen⁵

and Peter Kryger Jensen⁵

¹ Department of Engineering, Aarhus University, 8000 Aarhus, Denmark

² The Maersk Mc-Kinney Moller Institute, University of Southern Denmark, 5230 Odense, Denmark

³ AGROINTELLI, 8200 Aarhus, Denmark

⁴ Danish Technological Institute, Robot Technology, 5230 Odense, Denmark

⁵ Department of Agroecology—Crop Health, Aarhus University, 4200 Slagelse, Denmark

Sensors 2016, 16(11), 1848; https://doi.org/10.3390/s16111848 - 4 Nov 2016

Cited by 23 | Viewed by 8031

Abstract

The stricter legislation within the European Union for the regulation of herbicides that are prone to leaching causes a greater economic burden on the agricultural industry through taxation. Owing to the increased economic burden, research in reducing herbicide usage has been prompted. High-resolution [...] Read more.

The stricter legislation within the European Union for the regulation of herbicides that are prone to leaching causes a greater economic burden on the agricultural industry through taxation. Owing to the increased economic burden, research in reducing herbicide usage has been prompted. High-resolution images from digital cameras support the studying of plant characteristics. These images can also be utilized to analyze shape and texture characteristics for weed identification. Instead of detecting weed patches, weed density can be estimated at a sub-patch level, through which even the identification of a single plant is possible. The aim of this study is to adapt the monocot and dicot coverage ratio vision (MoDiCoVi) algorithm to estimate dicotyledon leaf cover, perform grid spraying in real time, and present initial results in terms of potential herbicide savings in maize. The authors designed and executed an automated, large-scale field trial supported by the Armadillo autonomous tool carrier robot. The field trial consisted of 299 maize plots. Half of the plots (parcels) were planned with additional seeded weeds; the other half were planned with naturally occurring weeds. The in-situ evaluation showed that, compared to conventional broadcast spraying, the proposed method can reduce herbicide usage by 65% without measurable loss in biological effect. Full article

(This article belongs to the Special Issue Vision-Based Sensors in Field Robotics)

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11 pages, 1175 KiB

Open AccessArticle

A Wideband Circularly Polarized Antenna with a Multiple-Circular-Sector Dielectric Resonator

by Son Trinh-Van

, Youngoo Yang, Kang-Yoon Lee and Keum Cheol Hwang^*

School of Electronic and Electrical Engineering, Sungkyunkwan University, Suwon 440-746, Korea

Sensors 2016, 16(11), 1849; https://doi.org/10.3390/s16111849 - 3 Nov 2016

Cited by 7 | Viewed by 6216

Abstract

This paper presents the design of a wideband circularly polarized antenna using a multiple-circular-sector dielectric resonator (DR). The DR is composed of twelve circular-sector DRs with identical central angles of 30

^{\circ}

but with different radii. A genetic algorithm is utilized to optimize [...] Read more.

This paper presents the design of a wideband circularly polarized antenna using a multiple-circular-sector dielectric resonator (DR). The DR is composed of twelve circular-sector DRs with identical central angles of 30

^{\circ}

but with different radii. A genetic algorithm is utilized to optimize the radii of the twelve circular-sector DRs to realize wideband circular polarization. The proposed antenna is excited using an aperture-coupled feeding technique through a narrow rectangular slot etched onto the ground plane. An antenna prototype is experimentally verified. The measured −10 dB reflection and 3 dB axial ratio (AR) bandwidths are 31.39% (1.88–2.58 GHz) and 19.30% (2.06–2.50 GHz), respectively, covering the operating bands of the following systems: UMTS-2100 (2.145 GHz), WiMAX (2.3 GHz), and Wi-Fi (2.445 GHz). A measured peak gain of 7.65 dBic at 2.225 GHz and gain variation of less than 2.70 dBic within the measured 3 dB AR bandwidth are achieved. In addition, the radiation patterns of the proposed antenna are presented and discussed. Full article

(This article belongs to the Special Issue Resonator Sensors)

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25 pages, 1132 KiB

Open AccessArticle

An Improved Forwarding of Diverse Events with Mobile Sinks in Underwater Wireless Sensor Networks

by Waseem Raza¹, Farzana Arshad¹, Imran Ahmed²

, Wadood Abdul³

, Sanaa Ghouzali⁴, Iftikhar Azim Niaz⁵

and Nadeem Javaid^5,*

¹ Department of Telecommunication Engineering, UET Taxila, Taxila 47080, Pakistan

² Institute of Management Sciences (IMS), Peshawar 25000, Pakistan

³ Department of Computer Engineering, College of Computer and Information Sciences, King Saud University, Riyadh 11633, Saudi Arabia

⁴ Information Technology Department, College of Computer and Information Sciences, King Saud University, Riyadh 11633, Saudi Arabia

⁵ COMSATS Institute of Information Technology, Islamabad 44000, Pakistan

Sensors 2016, 16(11), 1850; https://doi.org/10.3390/s16111850 - 4 Nov 2016

Cited by 3 | Viewed by 5133

Abstract

In this paper, a novel routing strategy to cater the energy consumption and delay sensitivity issues in deep underwater wireless sensor networks is proposed. This strategy is named as ESDR: Event Segregation based Delay sensitive Routing. In this strategy sensed events are segregated [...] Read more.

In this paper, a novel routing strategy to cater the energy consumption and delay sensitivity issues in deep underwater wireless sensor networks is proposed. This strategy is named as ESDR: Event Segregation based Delay sensitive Routing. In this strategy sensed events are segregated on the basis of their criticality and, are forwarded to their respective destinations based on forwarding functions. These functions depend on different routing metrics like: Signal Quality Index, Localization free Signal to Noise Ratio, Energy Cost Function and Depth Dependent Function. The problem of incomparable values of previously defined forwarding functions causes uneven delays in forwarding process. Hence forwarding functions are redefined to ensure their comparable values in different depth regions. Packet forwarding strategy is based on the event segregation approach which forwards one third of the generated events (delay sensitive) to surface sinks and two third events (normal events) are forwarded to mobile sinks. Motion of mobile sinks is influenced by the relative distribution of normal nodes. We have also incorporated two different mobility patterns named as; adaptive mobility and uniform mobility for mobile sinks. The later one is implemented for collecting the packets generated by the normal nodes. These improvements ensure optimum holding time, uniform delay and in-time reporting of delay sensitive events. This scheme is compared with the existing ones and outperforms the existing schemes in terms of network lifetime, delay and throughput. Full article

(This article belongs to the Special Issue Sensing Technologies for Autonomy and Cooperation in Underwater Networked Robot Systems)

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19 pages, 4570 KiB

Open AccessArticle

In Vivo Neural Recording and Electrochemical Performance of Microelectrode Arrays Modified by Rough-Surfaced AuPt Alloy Nanoparticles with Nanoporosity

by Zongya Zhao^1,2, Ruxue Gong^1,2, Liang Zheng^1,2 and Jue Wang^1,2,*

¹ Key Laboratory of Biomedical Information Engineering of the Ministry of Education, Institute of Biomedical Engineering, School of Life Science and Technology, Xi’an Jiaotong University, Xi’an 710049, China

² National Engineering Research Center of Health Care and Medical Devices, Xi’an Jiaotong University Branch, Xi’an 710049, China

Sensors 2016, 16(11), 1851; https://doi.org/10.3390/s16111851 - 3 Nov 2016

Cited by 25 | Viewed by 6696

Abstract

In order to reduce the impedance and improve in vivo neural recording performance of our developed Michigan type silicon electrodes, rough-surfaced AuPt alloy nanoparticles with nanoporosity were deposited on gold microelectrode sites through electro-co-deposition of Au-Pt-Cu alloy nanoparticles, followed by chemical dealloying Cu. [...] Read more.

In order to reduce the impedance and improve in vivo neural recording performance of our developed Michigan type silicon electrodes, rough-surfaced AuPt alloy nanoparticles with nanoporosity were deposited on gold microelectrode sites through electro-co-deposition of Au-Pt-Cu alloy nanoparticles, followed by chemical dealloying Cu. The AuPt alloy nanoparticles modified gold microelectrode sites were characterized by scanning electron microscopy (SEM), electrochemical impedance spectroscopy (EIS), cyclic voltammetry (CV) and in vivo neural recording experiment. The SEM images showed that the prepared AuPt alloy nanoparticles exhibited cauliflower-like shapes and possessed very rough surfaces with many different sizes of pores. Average impedance of rough-surfaced AuPt alloy nanoparticles modified sites was 0.23 MΩ at 1 kHz, which was only 4.7% of that of bare gold microelectrode sites (4.9 MΩ), and corresponding in vitro background noise in the range of 1 Hz to 7500 Hz decreased to 7.5

μ V_{rms}

from 34.1

μ V_{rms}

at bare gold microelectrode sites. Spontaneous spike signal recording was used to evaluate in vivo neural recording performance of modified microelectrode sites, and results showed that rough-surfaced AuPt alloy nanoparticles modified microelectrode sites exhibited higher average spike signal-to-noise ratio (SNR) of 4.8 in lateral globus pallidus (GPe) due to lower background noise compared to control microelectrodes. Electro-co-deposition of Au-Pt-Cu alloy nanoparticles combined with chemical dealloying Cu was a convenient way for increasing the effective surface area of microelectrode sites, which could reduce electrode impedance and improve the quality of in vivo spike signal recording. Full article

(This article belongs to the Special Issue Applications of Advanced Materials on Microelectronic and Optical Sensors)

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25 pages, 8874 KiB

Open AccessArticle

An Arrival and Departure Time Predictor for Scheduling Communication in Opportunistic IoT

by Riccardo Pozza^1,*

, Stylianos Georgoulas¹, Klaus Moessner¹

, Michele Nati², Alexander Gluhak² and Srdjan Krco³

¹ Institute for Communication Systems, University of Surrey, Guildford GU2 7XH, UK

² Digital Catapult Centre, London NW1 2RA, UK

³ Dunav Net, Novi Sad 21000, Serbia

Sensors 2016, 16(11), 1852; https://doi.org/10.3390/s16111852 - 4 Nov 2016

Cited by 3 | Viewed by 6266

Abstract

In this article, an Arrival and Departure Time Predictor (ADTP) for scheduling communication in opportunistic Internet of Things (IoT) is presented. The proposed algorithm learns about temporal patterns of encounters between IoT devices and predicts future arrival and departure times, therefore future contact [...] Read more.

In this article, an Arrival and Departure Time Predictor (ADTP) for scheduling communication in opportunistic Internet of Things (IoT) is presented. The proposed algorithm learns about temporal patterns of encounters between IoT devices and predicts future arrival and departure times, therefore future contact durations. By relying on such predictions, a neighbour discovery scheduler is proposed, capable of jointly optimizing discovery latency and power consumption in order to maximize communication time when contacts are expected with high probability and, at the same time, saving power when contacts are expected with low probability. A comprehensive performance evaluation with different sets of synthetic and real world traces shows that ADTP performs favourably with respect to previous state of the art. This prediction framework opens opportunities for transmission planners and schedulers optimizing not only neighbour discovery, but the entire communication process. Full article

(This article belongs to the Special Issue Smart City: Vision and Reality)

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17 pages, 3181 KiB

Open AccessArticle

Strain Measurement in Aluminium Alloy during the Solidification Process Using Embedded Fibre Bragg Gratings

by Klaus Weraneck^1,*, Florian Heilmeier², Markus Lindner³, Moritz Graf¹, Martin Jakobi¹, Wolfram Volk², Johannes Roths³

and Alexander W. Koch¹

¹ Institute for Measurement Systems and Sensor Technology, Technical University of Munich, 80333 Munich, Germany

² Chair of Metal Forming and Casting, Technical University of Munich, 85748 Garching, Germany

³ Photonics Laboratory, Munich University of Applied Sciences, 80335 Munich, Germany

Sensors 2016, 16(11), 1853; https://doi.org/10.3390/s16111853 - 4 Nov 2016

Cited by 19 | Viewed by 6139

Abstract

In recent years, the observation of the behaviour of components during the production process and over their life cycle is of increasing importance. Structural health monitoring, for example of carbon composites, is state-of-the-art research. The usage of Fibre Bragg Gratings (FBGs) in this [...] Read more.

In recent years, the observation of the behaviour of components during the production process and over their life cycle is of increasing importance. Structural health monitoring, for example of carbon composites, is state-of-the-art research. The usage of Fibre Bragg Gratings (FBGs) in this field is of major advantage. Another possible area of application is in foundries. The internal state of melts during the solidification process is of particular interest. By using embedded FBGs, temperature and stress can be monitored during the process. In this work, FBGs were embedded in aluminium alloys in order to observe the occurring strain. Two different FBG positions were chosen in the mould in order to compare its dependence. It was shown that FBGs can withstand the solidification process, although a compression in the range of one percent was measured, which is in agreement with the literature value. Furthermore, different lengths of the gratings were applied, and it was shown that shorter gratings result in more accurate measurements. The obtained results prove that FBGs are applicable as sensors for temperatures up to 740 °C. Full article

(This article belongs to the Special Issue Optical Fiber Sensors 2016)

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17 pages, 2512 KiB

Open AccessArticle

Analytical Study on Multi-Tier 5G Heterogeneous Small Cell Networks: Coverage Performance and Energy Efficiency

by Zhu Xiao^1,2

, Hongjing Liu¹, Vincent Havyarimana¹

, Tong Li¹ and Dong Wang^1,*

¹ College of Computer Science and Electronic Engineering, Hunan University, Changsha 410082, China

² State Key Laboratory of Integrated Service Networks, Xidian University, Xi’an 710071, China

Sensors 2016, 16(11), 1854; https://doi.org/10.3390/s16111854 - 4 Nov 2016

Cited by 33 | Viewed by 6139

Abstract

In this paper, we investigate the coverage performance and energy efficiency of multi-tier heterogeneous cellular networks (HetNets) which are composed of macrocells and different types of small cells, i.e., picocells and femtocells. By virtue of stochastic geometry tools, we model the multi-tier HetNets [...] Read more.

In this paper, we investigate the coverage performance and energy efficiency of multi-tier heterogeneous cellular networks (HetNets) which are composed of macrocells and different types of small cells, i.e., picocells and femtocells. By virtue of stochastic geometry tools, we model the multi-tier HetNets based on a Poisson point process (PPP) and analyze the Signal to Interference Ratio (SIR) via studying the cumulative interference from pico-tier and femto-tier. We then derive the analytical expressions of coverage probabilities in order to evaluate coverage performance in different tiers and investigate how it varies with the small cells’ deployment density. By taking the fairness and user experience into consideration, we propose a disjoint channel allocation scheme and derive the system channel throughput for various tiers. Further, we formulate the energy efficiency optimization problem for multi-tier HetNets in terms of throughput performance and resource allocation fairness. To solve this problem, we devise a linear programming based approach to obtain the available area of the feasible solutions. System-level simulations demonstrate that the small cells’ deployment density has a significant effect on the coverage performance and energy efficiency. Simulation results also reveal that there exits an optimal small cell base station (SBS) density ratio between pico-tier and femto-tier which can be applied to maximize the energy efficiency and at the same time enhance the system performance. Our findings provide guidance for the design of multi-tier HetNets for improving the coverage performance as well as the energy efficiency. Full article

(This article belongs to the Section Sensor Networks)

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31 pages, 1592 KiB

Open AccessArticle

A Methodological Approach for Assessing Amplified Reflection Distributed Denial of Service on the Internet of Things

by João José Costa Gondim¹, Robson De Oliveira Albuquerque¹

, Anderson Clayton Alves Nascimento^1,2, Luis Javier García Villalba^3,*

and Tai-Hoon Kim⁴

¹ Electrical Engineering Department, University of Brasília, Campus Universitário Darci Ribeiro, 70919-970 Brasília DF, Brazil

² Center for Data Science, Institute of Technology, University of Washington, Tacoma, WA 98402-3100, USA

³ Group of Analysis, Security and Systems (GASS), Department of Software Engineering and Artificial Intelligence (DISIA), Faculty of Computer Science and Engineering, Office 431, Universidad Complutense de Madrid (UCM), Calle Profesor José García Santesmases, 9, Ciudad Universitaria, Madrid 28040, Spain

⁴ Department of Convergence Security, Sungshin Women’s University, 249-1 Dongseon-Dong 3-ga, Seoul 136-742, Korea

Sensors 2016, 16(11), 1855; https://doi.org/10.3390/s16111855 - 4 Nov 2016

Cited by 21 | Viewed by 8877

Abstract

Concerns about security on Internet of Things (IoT) cover data privacy and integrity, access control, and availability. IoT abuse in distributed denial of service attacks is a major issue, as typical IoT devices’ limited computing, communications, and power resources are prioritized in implementing [...] Read more.

Concerns about security on Internet of Things (IoT) cover data privacy and integrity, access control, and availability. IoT abuse in distributed denial of service attacks is a major issue, as typical IoT devices’ limited computing, communications, and power resources are prioritized in implementing functionality rather than security features. Incidents involving attacks have been reported, but without clear characterization and evaluation of threats and impacts. The main purpose of this work is to methodically assess the possible impacts of a specific class–amplified reflection distributed denial of service attacks (AR-DDoS)–against IoT. The novel approach used to empirically examine the threat represented by running the attack over a controlled environment, with IoT devices, considered the perspective of an attacker. The methodology used in tests includes that perspective, and actively prospects vulnerabilities in computer systems. This methodology defines standardized procedures for tool-independent vulnerability assessment based on strategy, and the decision flows during execution of penetration tests (pentests). After validation in different scenarios, the methodology was applied in amplified reflection distributed denial of service (AR-DDoS) attack threat assessment. Results show that, according to attack intensity, AR-DDoS saturates reflector infrastructure. Therefore, concerns about AR-DDoS are founded, but expected impact on abused IoT infrastructure and devices will be possibly as hard as on final victims. Full article

(This article belongs to the Special Issue Topology Control in Emerging Sensor Networks)

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9 pages, 1096 KiB

Open AccessArticle

The Development of a Portable SPR Bioanalyzer for Sensitive Detection of Escherichia coli O157:H7

by Shun Wang^1,2, Jiufeng Xie³, Min Jiang³, Keke Chang^1,2, Ruipeng Chen^1,2, Liuzheng Ma^1,2, Juanhua Zhu¹, Qingqian Guo^1,2, Haifeng Sun^1,2 and Jiandong Hu^1,2,*

¹ Department of Electrical Engineering, Henan Agricultural University, Zhengzhou 45002, China

² State Key Laboratory of Wheat and Maize Crop Science, Zhengzhou 45002, China

³ College of life sciences, Henan Agricultural University, Zhengzhou 45002, China

Sensors 2016, 16(11), 1856; https://doi.org/10.3390/s16111856 - 4 Nov 2016

Cited by 35 | Viewed by 6940

Abstract

The purpose of this study was to develop a portable surface plasmon resonance (SPR) bioanalyzer for the sensitive detection of Escherichia coli O157:H7 in comparison with an enzyme-linked immunosorbent assay (ELISA). The experimental setup mainly consisted of an integrated biosensor and a homemade [...] Read more.

The purpose of this study was to develop a portable surface plasmon resonance (SPR) bioanalyzer for the sensitive detection of Escherichia coli O157:H7 in comparison with an enzyme-linked immunosorbent assay (ELISA). The experimental setup mainly consisted of an integrated biosensor and a homemade microfluidic cell with a three-way solenoid valve. In order to detect Escherichia coli O157:H7 using the SPR immunoassay, 3-mercaptopropionic acid (3-MPA) was chemisorbed onto a gold surface via covalent bond for the immobilization of biological species. 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide hydrochloride (EDC) and N-hydroxysuccinimide (NHS) were used as crosslinker reagents to enable the reaction between 3-MPA and Escherichia coli O157:H7 antibodies by covalent –CO–NH– amide bonding. The experimental results were obtained from the Escherichia coli O157:H7 positive samples prepared by 10-, 20-, 40-, 80-, and 160-fold dilution respectively, which show that a good linear relationship with the correlation coefficient R of 0.982 existed between the response units from the portable SPR bioanalyzer and the concentration of Escherichia coli O157:H7 positive samples. Moreover, the theoretical detection limit of 1.87 × 10³ cfu/mL was calculated from the positive control samples. Compared with the Escherichia coli O157:H7 ELISA kit, the sensitivity of this portable SPR bioanalyzer is four orders of magnitude higher than the ELISA kit. The results demonstrate that the portable SPR bioanalyzer could provide an alternative method for the quantitative and sensitive determination of Escherichia coli O157:H7 in field. Full article

(This article belongs to the Section Biosensors)

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10 pages, 5862 KiB

Open AccessArticle

Improvement of Toluene-Sensing Performance of SnO₂ Nanofibers by Pt Functionalization

by Jae-Hun Kim, Zain Ul Abideen, Yifang Zheng and Sang Sub Kim^*

Department of Materials Science and Engineering, Inha University, Incheon 402-751, Korea

Sensors 2016, 16(11), 1857; https://doi.org/10.3390/s16111857 - 4 Nov 2016

Cited by 24 | Viewed by 6117

Abstract

Functionalization of metal nanoparticles (NPs) on oxide materials is a commonly employed technique for enhancing the sensitivity and selectivity of materials for gas sensing applications. In this study, we functionalized electrospinning-synthesized SnO₂ nanofibers (NFs) with various amounts of Pt NPs to enhance [...] Read more.

Functionalization of metal nanoparticles (NPs) on oxide materials is a commonly employed technique for enhancing the sensitivity and selectivity of materials for gas sensing applications. In this study, we functionalized electrospinning-synthesized SnO₂ nanofibers (NFs) with various amounts of Pt NPs to enhance the toluene-sensing properties. In particular, Pt NPs were prepared by deposition of Pt films by sputtering and subsequent heat treatment. Electronic and chemical sensitizations by the Pt NPs were responsible for the improved toluene sensitivity. The best sensing properties were achieved at an optimized amount of Pt NPs, showing a volcano shape in relation to the amount of Pt NPs. The method used in this study is useful for the development of toluene-sensitive and -selective chemiresistive NF-based gas sensors. Full article

(This article belongs to the Special Issue Chemiresistive Sensors)

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16 pages, 11812 KiB

Open AccessArticle

MATE: Machine Learning for Adaptive Calibration Template Detection

by Simon Donné^*

, Jonas De Vylder, Bart Goossens and Wilfried Philips

iMinds - IPI, Ghent University, Ghent B-9000, Belgium

Sensors 2016, 16(11), 1858; https://doi.org/10.3390/s16111858 - 4 Nov 2016

Cited by 33 | Viewed by 8026

Abstract

The problem of camera calibration is two-fold. On the one hand, the parameters are estimated from known correspondences between the captured image and the real world. On the other, these correspondences themselves—typically in the form of chessboard corners—need to be found. Many distinct [...] Read more.

The problem of camera calibration is two-fold. On the one hand, the parameters are estimated from known correspondences between the captured image and the real world. On the other, these correspondences themselves—typically in the form of chessboard corners—need to be found. Many distinct approaches for this feature template extraction are available, often of large computational and/or implementational complexity. We exploit the generalized nature of deep learning networks to detect checkerboard corners: our proposed method is a convolutional neural network (CNN) trained on a large set of example chessboard images, which generalizes several existing solutions. The network is trained explicitly against noisy inputs, as well as inputs with large degrees of lens distortion. The trained network that we evaluate is as accurate as existing techniques while offering improved execution time and increased adaptability to specific situations with little effort. The proposed method is not only robust against the types of degradation present in the training set (lens distortions, and large amounts of sensor noise), but also to perspective deformations, e.g., resulting from multi-camera set-ups. Full article

(This article belongs to the Section Physical Sensors)

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10 pages, 2495 KiB

Open AccessArticle

A Method to Estimate Sunshine Duration Using Cloud Classification Data from a Geostationary Meteorological Satellite (FY-2D) over the Heihe River Basin

by Bingfang Wu^*

, Shufu Liu, Weiwei Zhu, Mingzhao Yu, Nana Yan and Qiang Xing

Institute of Remote Sensing and Digital Earth (RADI), Chinese Academy of Sciences, Beijing 100094, China

Sensors 2016, 16(11), 1859; https://doi.org/10.3390/s16111859 - 4 Nov 2016

Cited by 18 | Viewed by 4794

Abstract

Sunshine duration is an important variable that is widely used in atmospheric energy balance studies, analysis of the thermal loadings on buildings, climate research, and the evaluation of agricultural resources. In most cases, it is calculated using an interpolation method based on regional-scale [...] Read more.

Sunshine duration is an important variable that is widely used in atmospheric energy balance studies, analysis of the thermal loadings on buildings, climate research, and the evaluation of agricultural resources. In most cases, it is calculated using an interpolation method based on regional-scale meteorological data from field stations. Accurate values in the field are difficult to obtain without ground measurements. In this paper, a satellite-based method to estimate sunshine duration is introduced and applied over the Heihe River Basin. This method is based on hourly cloud classification product data from the FY-2D geostationary meteorological satellite (FY-2D). A new index—FY-2D cloud type sunshine factor—is proposed, and the Shuffled Complex Evolution Algorithm (SCE-UA) was used to calibrate sunshine factors from different coverage types based on ground measurement data from the Heihe River Basin in 2007. The estimated sunshine duration from the proposed new algorithm was validated with ground observation data for 12 months in 2008, and the spatial distribution was compared with the results of an interpolation method over the Heihe River Basin. The study demonstrates that geostationary satellite data can be used to successfully estimate sunshine duration. Potential applications include climate research, energy balance studies, and global estimations of evapotranspiration. Full article

(This article belongs to the Section Remote Sensors)

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14 pages, 2994 KiB

Open AccessArticle

High-Throughput Phenotyping of Wheat and Barley Plants Grown in Single or Few Rows in Small Plots Using Active and Passive Spectral Proximal Sensing

by Gero Barmeier and Urs Schmidhalter^*

Chair of Plant Nutrition, Department of Plant Sciences, Technical University of Munich, Emil-Ramann-Str. 2, Freising 85354, Germany

Sensors 2016, 16(11), 1860; https://doi.org/10.3390/s16111860 - 5 Nov 2016

Cited by 30 | Viewed by 6281

Abstract

In the early stages of plant breeding, breeders evaluate a large number of varieties. Due to limited availability of seeds and space, plot sizes may range from one to four rows. Spectral proximal sensors can be used in place of labour-intensive methods to [...] Read more.

In the early stages of plant breeding, breeders evaluate a large number of varieties. Due to limited availability of seeds and space, plot sizes may range from one to four rows. Spectral proximal sensors can be used in place of labour-intensive methods to estimate specific plant traits. The aim of this study was to test the performance of active and passive sensing to assess single and multiple rows in a breeding nursery. A field trial with single cultivars of winter barley and winter wheat with four plot designs (single-row, wide double-row, three rows, and four rows) was conducted. A GreenSeeker RT100 and a passive bi-directional spectrometer were used to assess biomass fresh and dry weight, as well as aboveground nitrogen content and uptake. Generally, spectral passive sensing and active sensing performed comparably in both crops. Spectral passive sensing was enhanced by the availability of optimized ratio vegetation indices, as well as by an optimized field of view and by reduced distance dependence. Further improvements of both sensors in detecting the performance of plants in single rows can likely be obtained by optimization of sensor positioning or orientation. The results suggest that even in early selection cycles, enhanced high-throughput phenotyping might be able to assess plant performance within plots comprising single or multiple rows. This method has significant potential for advanced breeding. Full article

(This article belongs to the Section Remote Sensors)

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14 pages, 2640 KiB

Open AccessArticle

Multi-Domain SDN Survivability for Agricultural Wireless Sensor Networks

by Tao Huang^1,2,*

, Siyu Yan^1,2, Fan Yang^1,2 and Jiang Liu^1,2

¹ State Key Laboratory of Networking and Switching Technology, BUPT, Beijing 100876, China

² Science and Technology on Information Transmission and Dissemination in Communication Networks Laboratory, Shijiazhuang 050081, China

Sensors 2016, 16(11), 1861; https://doi.org/10.3390/s16111861 - 6 Nov 2016

Cited by 12 | Viewed by 6705

Abstract

Wireless sensor networks (WSNs) have been widely applied in agriculture field; meanwhile, the advent of multi-domain software-defined networks (SDNs) have improved the wireless resource utilization rate and strengthened network management. In recent times, multi-domain SDNs have been applied to agricultural sensor networks, namely [...] Read more.

Wireless sensor networks (WSNs) have been widely applied in agriculture field; meanwhile, the advent of multi-domain software-defined networks (SDNs) have improved the wireless resource utilization rate and strengthened network management. In recent times, multi-domain SDNs have been applied to agricultural sensor networks, namely multi-domain software-defined wireless sensor networks (SDWSNs). However, when the SDNs controlling agriculture networks suddenly become unavailable, whether intra-domain or inter-domain, sensor network communication is abnormal because of the loss of control. Moreover, there are controller and switch info-updating problems even if the controller becomes available again. To resolve these problems, this paper proposes a new approach based on an Open vSwitch extension for multi-domain SDWSNs, which can enhance agriculture network survivability and stability. We achieved this by designing a connection-state mechanism, a communication mechanism on both L2 and L3, and an info-updating mechanism based on Open vSwitch. The experimental results show that, whether it is agricultural inter-domain or intra-domain during the controller failure period, the sensor switches can enter failure recovery mode as soon as possible so that the sensor network keeps a stable throughput, a short failure recovery time below 300 ms, and low packet loss. Further, the domain can smoothly control the domain network again once the controller becomes available. This approach based on an Open vSwitch extension can enhance the survivability and stability of multi-domain SDWSNs in precision agriculture. Full article

(This article belongs to the Special Issue Sensors for Agriculture)

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17 pages, 30957 KiB

Open AccessArticle

Power Transmission Tower Series Extraction in PolSAR Image Based on Time-Frequency Analysis and A-Contrario Theory

by Dongqing Peng, Haijian Zhang^*, Wei Guo and Wen Yang

School of Electronic Information, Wuhan University, Wuhan 430072, China

Sensors 2016, 16(11), 1862; https://doi.org/10.3390/s16111862 - 5 Nov 2016

Cited by 2 | Viewed by 4806

Abstract

Based on Time-Frequency (TF) analysis and a-contrario theory, this paper presents a new approach for extraction of linear arranged power transmission tower series in Polarimetric Synthetic Aperture Radar (PolSAR) images. Firstly, the PolSAR multidimensional information is analyzed using a linear TF decomposition approach. [...] Read more.

Based on Time-Frequency (TF) analysis and a-contrario theory, this paper presents a new approach for extraction of linear arranged power transmission tower series in Polarimetric Synthetic Aperture Radar (PolSAR) images. Firstly, the PolSAR multidimensional information is analyzed using a linear TF decomposition approach. The stationarity of each pixel is assessed by testing the maximum likelihood ratio statistics of the coherency matrix. Then, based on the maximum likelihood log-ratio image, a Cell-Averaging Constant False Alarm Rate (CA-CFAR) detector with Weibull clutter background and a post-processing operator is used to detect point-like targets in the image. Finally, a searching approach based on a-contrario theory is applied to extract the linear arranged targets from detected point-like targets. The experimental results on three sets of PolSAR data verify the effectiveness of this approach. Full article

(This article belongs to the Section Remote Sensors)

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30 pages, 3692 KiB

Open AccessReview

Electrochemical Affinity Biosensors Based on Disposable Screen-Printed Electrodes for Detection of Food Allergens

by Alina Vasilescu¹

, Gilvanda Nunes²

, Akhtar Hayat³, Usman Latif³

and Jean-Louis Marty^4,*

¹ International Centre of Biodynamics, 1B Intrarea Portocalelor, sector 6, 060101 Bucharest, Romania

² Technological Chemistry Department, Federal University of Maranhão, CCET/UFMA, Av. Portugueses, Cidade Universitária do Canga, 65080-040 São Luis, MA, Brazil

³ Interdisciplinary Research Centre in Biomedical Materials (IRCBM) COMSATS Institute of Information Technology (CIIT), 54000 Lahore, Pakistan

⁴ BAE Laboratory, Université de Perpignan Via Domitia, 52 Avenue Paul Alduy, 66860 Perpignan, France

Sensors 2016, 16(11), 1863; https://doi.org/10.3390/s16111863 - 5 Nov 2016

Cited by 76 | Viewed by 14929

Abstract

Food allergens are proteins from nuts and tree nuts, fish, shellfish, wheat, soy, eggs or milk which trigger severe adverse reactions in the human body, involving IgE-type antibodies. Sensitive detection of allergens in a large variety of food matrices has become increasingly important [...] Read more.

Food allergens are proteins from nuts and tree nuts, fish, shellfish, wheat, soy, eggs or milk which trigger severe adverse reactions in the human body, involving IgE-type antibodies. Sensitive detection of allergens in a large variety of food matrices has become increasingly important considering the emergence of functional foods and new food manufacturing technologies. For example, proteins such as casein from milk or lysozyme and ovalbumin from eggs are sometimes used as fining agents in the wine industry. Nonetheless, allergen detection in processed foods is a challenging endeavor, as allergen proteins are degraded during food processing steps involving heating or fermentation. Detection of food allergens was primarily achieved via Enzyme-Linked Immuno Assay (ELISA) or by chromatographic methods. With the advent of biosensors, electrochemical affinity-based biosensors such as those incorporating antibodies and aptamers as biorecognition elements were also reported in the literature. In this review paper, we highlight the success achieved in the design of electrochemical affinity biosensors based on disposable screen-printed electrodes towards detection of protein allergens. We will discuss the analytical figures of merit for various disposable screen-printed affinity sensors in relation to methodologies employed for immobilization of bioreceptors on transducer surface. Full article

(This article belongs to the Special Issue Recent Advances in Biosensors Based Screen Printed Platforms)

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13 pages, 6241 KiB

Open AccessArticle

Calorimetry Minisensor for the Localised Measurement of Surface Heat Dissipated from the Human Body

by Fabiola Socorro

, Pedro Jesús Rodríguez de Rivera and Manuel Rodríguez de Rivera^*

Departamento de Física, Universidad de Las Palmas de Gran Canaria, Las Palmas de Gran Canaria E-35017, Spain

Sensors 2016, 16(11), 1864; https://doi.org/10.3390/s16111864 - 6 Nov 2016

Cited by 10 | Viewed by 7262

Abstract

We have developed a calorimetry sensor that can perform a local measurement of the surface heat dissipated from the human body. The operating principle is based on the law of conductive heat transfer: heat dissipated by the human body passes across a thermopile [...] Read more.

We have developed a calorimetry sensor that can perform a local measurement of the surface heat dissipated from the human body. The operating principle is based on the law of conductive heat transfer: heat dissipated by the human body passes across a thermopile located between the individual and a thermostat. Body heat power is calculated from the signals measured by the thermopile and the amount of power dissipated across the thermostat in order to maintain a constant temperature. The first prototype we built had a detection area measuring 6 × 6 cm², while the second prototype, which is described herein, had a 2 × 2 cm² detection area. This new design offers three advantages over the initial one: (1) greater resolution and three times greater thermal sensitivity; (2) a twice as fast response; and (3) it can take measurements from smaller areas of the body. The sensor has a 5 mW resolution, but the uncertainty is greater, up to 15 mW, due to the measurement and calculation procedure. The order of magnitude of measurements made in healthy subjects ranged from 60 to 300 mW at a thermostat temperature of 28 °C and an ambient room temperature of 21 °C. The values measured by the sensor depend on the ambient temperature and the thermostat’s temperature, while the power dissipated depends on the individual’s metabolism and any physical and/or emotional activity. Full article

(This article belongs to the Special Issue Sensing Technology for Healthcare System)

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18 pages, 3389 KiB

Open AccessArticle

Energy-Efficient Heterogeneous Wireless Sensor Deployment with Multiple Objectives for Structural Health Monitoring

by Chengyin Liu¹, Zhaoshuo Jiang^2,*, Fei Wang³ and Hui Chen¹

¹ Department of Civil and Environmental Engineering, Harbin Institute of Technology Shenzhen Graduate School, Shenzhen 518055, China

² School of Engineering, San Francisco State University, San Francisco, CA 94132, USA

³ Department of Electronic and Information Engineering, Harbin Institute of Technology Shenzhen Graduate School, Shenzhen 518055, China

Sensors 2016, 16(11), 1865; https://doi.org/10.3390/s16111865 - 6 Nov 2016

Cited by 6 | Viewed by 4183

Abstract

Heterogeneous wireless sensor networks (HWSNs) are widely adopted in structural health monitoring systems due to their potential for implementing sophisticated algorithms by integrating a diverse set of devices and improving a network’s sensing performance. However, deploying such a HWSN is still in a [...] Read more.

Heterogeneous wireless sensor networks (HWSNs) are widely adopted in structural health monitoring systems due to their potential for implementing sophisticated algorithms by integrating a diverse set of devices and improving a network’s sensing performance. However, deploying such a HWSN is still in a challenge due to the heterogeneous nature of the data and the energy constraints of the network. To respond to these challenges, an optimal deployment framework in terms of both modal information quality and energy consumption is proposed in this study. This framework generates a multi-objective function aimed at maximizing the quality of the modal information identified from heterogeneous data while minimizing the consumption of energy within the network at the same time. Particle swarm optimization algorithm is then implemented to seek solutions to the function effectively. After laying out the proposed sensor-optimization framework, a methodology is present to determine the clustering of the sensors to further conserve energy. Finally, a numerical verification is performed on a four-span pre-stressed reinforced concrete box-girder bridge. Results show that a set of strategically positioned heterogeneous sensors can maintain a balanced trade-off between the modal information accuracy and energy consumption. It is also observed that an appropriate cluster-tree network topology can further achieve energy saving in HWSNs. Full article

(This article belongs to the Section Physical Sensors)

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15 pages, 5227 KiB

Open AccessArticle

Simultaneous Life Detection and Localization Using a Wideband Chaotic Signal with an Embedded Tone

by Li Liu^1,2,*, Chaoyi Guo^1,2, Jingxia Li^1,2

, Hang Xu^1,2, Jianguo Zhang^1,2 and Bingjie Wang^1,2

¹ Key Laboratory of Advanced Transducers & Intelligent Control System, Ministry of Education and Shanxi Province, Taiyuan University of Technology, Taiyuan 030024, China

² College of Physics & Optoelectronics, Taiyuan University of Technology, Taiyuan 030024, China

Sensors 2016, 16(11), 1866; https://doi.org/10.3390/s16111866 - 6 Nov 2016

Cited by 11 | Viewed by 7097

Abstract

A hybrid life detection radar system which transmits a wideband chaotic signal containing an embedded single-tone is proposed. The chaotic signal is used for target localization by the time-domain correlation method and synthetic aperture technique, and the single-tone signal is used to measure [...] Read more.

A hybrid life detection radar system which transmits a wideband chaotic signal containing an embedded single-tone is proposed. The chaotic signal is used for target localization by the time-domain correlation method and synthetic aperture technique, and the single-tone signal is used to measure the frequencies of breathing and heartbeat based on an on-chip split-ring integrated sensor and Michelson interference principle. Experimental results in free space and in through-wall scenarios demonstrate that the system can realize human detection and localization simultaneously with high range resolution, high sensitivity, and large dynamic range without complex signal processing. The range resolution is about 10 cm, and the dynamic range is 35 dB for the respiration signal detection and 25 dB for the heartbeat signal detection. Due to its good immunity to interference/jamming and high spectrum efficiency, the proposed system is suitable for post-disaster rescue, elder/infant/patient vitality monitoring, and anti-terrorism enforcement applications. Full article

(This article belongs to the Special Issue Advanced Technologies and Techniques for Microwave and Wireless Sensors)

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19 pages, 7142 KiB

Open AccessArticle

Noise Reduction Effect of Multiple-Sampling-Based Signal-Readout Circuits for Ultra-Low Noise CMOS Image Sensors

by Shoji Kawahito^* and Min-Woong Seo

Research Institute of Electronics, Shizuoka University, Shizuoka 432-8011, Japan

Sensors 2016, 16(11), 1867; https://doi.org/10.3390/s16111867 - 6 Nov 2016

Cited by 24 | Viewed by 12422

Abstract

This paper discusses the noise reduction effect of multiple-sampling-based signal readout circuits for implementing ultra-low-noise image sensors. The correlated multiple sampling (CMS) technique has recently become an important technology for high-gain column readout circuits in low-noise CMOS image sensors (CISs). This paper reveals [...] Read more.

This paper discusses the noise reduction effect of multiple-sampling-based signal readout circuits for implementing ultra-low-noise image sensors. The correlated multiple sampling (CMS) technique has recently become an important technology for high-gain column readout circuits in low-noise CMOS image sensors (CISs). This paper reveals how the column CMS circuits, together with a pixel having a high-conversion-gain charge detector and low-noise transistor, realizes deep sub-electron read noise levels based on the analysis of noise components in the signal readout chain from a pixel to the column analog-to-digital converter (ADC). The noise measurement results of experimental CISs are compared with the noise analysis and the effect of noise reduction to the sampling number is discussed at the deep sub-electron level. Images taken with three CMS gains of two, 16, and 128 show distinct advantage of image contrast for the gain of 128 (noise(median): 0.29 e⁻_rms) when compared with the CMS gain of two (2.4 e⁻_rms), or 16 (1.1 e⁻_rms). Full article

(This article belongs to the Special Issue Photon-Counting Image Sensors)

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16 pages, 4057 KiB

Open AccessArticle

Traffic Vehicle Counting in Jam Flow Conditions Using Low-Cost and Energy-Efficient Wireless Magnetic Sensors

by Xu Bao¹

, Haijian Li^2,3,*

, Dongwei Xu⁴, Limin Jia⁵, Bin Ran³ and Jian Rong²

¹ Key Laboratory for Traffic and Transportation Security of Jiangsu Province, Huaiyin Institute of Technology, Huai’an 223003, China

² Beijing Key Laboratory of Traffic Engineering, Beijing University of Technology, Beijing 100124, China

³ Department of Civil and Environmental Engineering, University of Wisconsin-Madison, Madison, WI 53706, USA

⁴ College of Information Engineering, Zhejiang University of Technology, Hangzhou 310014, China

⁵ State Key Laboratory of Rail Traffic Control and Safety, Beijing Jiaotong University, Beijing 100044, China

Sensors 2016, 16(11), 1868; https://doi.org/10.3390/s16111868 - 6 Nov 2016

Cited by 32 | Viewed by 9180

Abstract

The jam flow condition is one of the main traffic states in traffic flow theory and the most difficult state for sectional traffic information acquisition. Since traffic information acquisition is the basis for the application of an intelligent transportation system, research on traffic [...] Read more.

The jam flow condition is one of the main traffic states in traffic flow theory and the most difficult state for sectional traffic information acquisition. Since traffic information acquisition is the basis for the application of an intelligent transportation system, research on traffic vehicle counting methods for the jam flow conditions has been worthwhile. A low-cost and energy-efficient type of multi-function wireless traffic magnetic sensor was designed and developed. Several advantages of the traffic magnetic sensor are that it is suitable for large-scale deployment and time-sustainable detection for traffic information acquisition. Based on the traffic magnetic sensor, a basic vehicle detection algorithm (DWVDA) with less computational complexity was introduced for vehicle counting in low traffic volume conditions. To improve the detection performance in jam flow conditions with a “tailgating effect” between front vehicles and rear vehicles, an improved vehicle detection algorithm (SA-DWVDA) was proposed and applied in field traffic environments. By deploying traffic magnetic sensor nodes in field traffic scenarios, two field experiments were conducted to test and verify the DWVDA and the SA-DWVDA algorithms. The experimental results have shown that both DWVDA and the SA-DWVDA algorithms yield a satisfactory performance in low traffic volume conditions (scenario I) and both of their mean absolute percent errors are less than 1% in this scenario. However, for jam flow conditions with heavy traffic volumes (scenario II), the SA-DWVDA was proven to achieve better results, and the mean absolute percent error of the SA-DWVDA is 2.54% with corresponding results of the DWVDA 7.07%. The results conclude that the proposed SA-DWVDA can implement efficient and accurate vehicle detection in jam flow conditions and can be employed in field traffic environments. Full article

(This article belongs to the Special Issue Vehicular Sensor Networks: Technical Challenges, Supports, and Application Experiences)

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12 pages, 5315 KiB

Open AccessArticle

Real-Time Location Tracking of Multiple Construction Laborers

by Jin-Sun Lim¹

, Ki-Il Song^2,*

and Hang-Lo Lee²

¹ R&D Center, SamwooIMC CO., LTD, Seoul 05660, Korea

² Department of Civil Engineering, Inha University, Incheon 22212, Korea

Sensors 2016, 16(11), 1869; https://doi.org/10.3390/s16111869 - 6 Nov 2016

Cited by 16 | Viewed by 6029

Abstract

A real-time location (RTL) system was developed to improve safety for multiple laborers in confined construction sites. The RTL system can monitor the location and movement of multiple laborers in real time. A portable RTL system with a low-battery mode was developed to [...] Read more.

A real-time location (RTL) system was developed to improve safety for multiple laborers in confined construction sites. The RTL system can monitor the location and movement of multiple laborers in real time. A portable RTL system with a low-battery mode was developed to accommodate various constraints in the construction site. A conventional RTL system that uses radio signal strength indicators (RSSIs) has high error, so an accelerometer with Bluetooth Low Energy (BLE) was added, and a calculation process is suggested. Field tests were performed for validation in underground construction and bridge overlay sites. The results show that the accelerometer and BLE can be used as effective sensors to detect the movement of laborers. When the sensor is fixed, the average error ranges 0.2–0.22 m, and when the sensor is moving, the average error ranges 0.1–0.47 m. Full article

(This article belongs to the Section Physical Sensors)

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17 pages, 19253 KiB

Open AccessArticle

Epipolar Rectification with Minimum Perspective Distortion for Oblique Images

by Jianchen Liu¹, Bingxuan Guo^2,*, Wanshou Jiang²

, Weishu Gong³ and Xiongwu Xiao²

¹ School of Remote Sensing and Information Engineering, Wuhan University, 129 Luoyu Road, Wuhan 430079, China

² State key Laboratory for Information Engineering in Surveying, Mapping and Remote Sensing, Wuhan University, 129 Luoyu Road, Wuhan 430079, China

³ Department of Geographical Sciences, University of Maryland, 2181 Samuel J. LeFrak Hall, 7251 Preinkert Drive, College Park, MD 20742, USA

Sensors 2016, 16(11), 1870; https://doi.org/10.3390/s16111870 - 7 Nov 2016

Cited by 5 | Viewed by 7653

Abstract

Epipolar rectification is of great importance for 3D modeling by using UAV (Unmanned Aerial Vehicle) images; however, the existing methods seldom consider the perspective distortion relative to surface planes. Therefore, an algorithm for the rectification of oblique images is proposed and implemented in [...] Read more.

Epipolar rectification is of great importance for 3D modeling by using UAV (Unmanned Aerial Vehicle) images; however, the existing methods seldom consider the perspective distortion relative to surface planes. Therefore, an algorithm for the rectification of oblique images is proposed and implemented in detail. The basic principle is to minimize the rectified images’ perspective distortion relative to the reference planes. First, this minimization problem is formulated as a cost function that is constructed by the tangent value of angle deformation; second, it provides a great deal of flexibility on using different reference planes, such as roofs and the façades of buildings, to generate rectified images. Furthermore, a reasonable scale is acquired according to the dihedral angle between the rectified image plane and the original image plane. The low-quality regions of oblique images are cropped out according to the distortion size. Experimental results revealed that the proposed rectification method can result in improved matching precision (Semi-global dense matching). The matching precision is increased by about 30% for roofs and increased by just 1% for façades, while the façades are not parallel to the baseline. In another designed experiment, the selected façades are parallel to the baseline, the matching precision has a great improvement for façades, by an average of 22%. This fully proves our proposed algorithm that elimination of perspective distortion on rectified images can significantly improve the accuracy of dense matching. Full article

(This article belongs to the Special Issue UAV-Based Remote Sensing)

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10 pages, 4623 KiB

Open AccessArticle

A Portable Smart-Phone Readout Device for the Detection of Mercury Contamination Based on an Aptamer-Assay Nanosensor

by Wei Xiao¹

, Meng Xiao¹, Qiangqiang Fu¹, Shiting Yu¹, Haicong Shen¹, Hongfen Bian¹ and Yong Tang^1,2,3,*

¹ Department of Bioengineering, Guangdong Province Key Laboratory of Molecular Immunology and Antibody Engineering, Jinan University, Guangzhou 510632, China

² Institute of Food Safety and Nutrition, Jinan University, Guangzhou 510632, China

³ Institute of Biotranslational Medicine, Jinan University, Guangzhou 510632, China

Sensors 2016, 16(11), 1871; https://doi.org/10.3390/s16111871 - 8 Nov 2016

Cited by 64 | Viewed by 9651

Abstract

The detection of environmental mercury (Hg) contamination requires complex and expensive instruments and professional technicians. We present a simple, sensitive, and portable Hg²⁺ detection system based on a smartphone and colorimetric aptamer nanosensor. A smartphone equipped with a light meter app was [...] Read more.

The detection of environmental mercury (Hg) contamination requires complex and expensive instruments and professional technicians. We present a simple, sensitive, and portable Hg²⁺ detection system based on a smartphone and colorimetric aptamer nanosensor. A smartphone equipped with a light meter app was used to detect, record, and process signals from a smartphone-based microwell reader (MR S-phone), which is composed of a simple light source and a miniaturized assay platform. The colorimetric readout of the aptamer nanosensor is based on a specific interaction between the selected aptamer and Hg²⁺, which leads to a color change in the reaction solution due to an aggregation of gold nanoparticles (AuNPs). The MR S-phone-based AuNPs-aptamer colorimetric sensor system could reliably detect Hg²⁺ in both tap water and Pearl River water samples and produced a linear colorimetric readout of Hg²⁺ concentration in the range of 1 ng/mL–32 ng/mL with a correlation of 0.991, and a limit of detection (LOD) of 0.28 ng/mL for Hg²⁺. The detection could be quickly completed in only 20 min. Our novel mercury detection assay is simple, rapid, and sensitive, and it provides new strategies for the on-site detection of mercury contamination in any environment. Full article

(This article belongs to the Section Biosensors)

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23 pages, 1808 KiB

Open AccessArticle

A Harmonized Perspective on Transportation Management in Smart Cities: The Novel IoT-Driven Environment for Road Traffic Modeling

by Pavel Masek^1,*, Jan Masek², Petr Frantik², Radek Fujdiak¹, Aleksandr Ometov³

, Jiri Hosek¹, Sergey Andreev³, Petr Mlynek¹ and Jiri Misurec¹

¹ Department of Telecommunications, Brno University of Technology, 61600 Brno, Czech Republic

² Institute of Structural Mechanics, Brno University of Technology, 60200 Brno, Czech Republic

³ Department of Electronics and Communications Engineering, Tampere University of Technology, 33720 Tampere, Finland

Sensors 2016, 16(11), 1872; https://doi.org/10.3390/s16111872 - 8 Nov 2016

Cited by 76 | Viewed by 15631

Abstract

The unprecedented growth of today’s cities together with increased population mobility are fueling the avalanche in the numbers of vehicles on the roads. This development led to the new challenges for the traffic management, including the mitigation of road congestion, accidents, and air [...] Read more.

The unprecedented growth of today’s cities together with increased population mobility are fueling the avalanche in the numbers of vehicles on the roads. This development led to the new challenges for the traffic management, including the mitigation of road congestion, accidents, and air pollution. Over the last decade, researchers have been focusing their efforts on leveraging the recent advances in sensing, communications, and dynamic adaptive technologies to prepare the deployed road traffic management systems (TMS) for resolving these important challenges in future smart cities. However, the existing solutions may still be insufficient to construct a reliable and secure TMS that is capable of handling the anticipated influx of the population and vehicles in urban areas. Along these lines, this work systematically outlines a perspective on a novel modular environment for traffic modeling, which allows to recreate the examined road networks in their full resemblance. Our developed solution is targeted to incorporate the progress in the Internet of Things (IoT) technologies, where low-power, embedded devices integrate as part of a next-generation TMS. To mimic the real traffic conditions, we recreated and evaluated a practical traffic scenario built after a complex road intersection within a large European city. Full article

(This article belongs to the Special Issue Smart City: Vision and Reality)

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16 pages, 2537 KiB

Open AccessArticle

A Fast Method to Calculate the Spatial Impulse Response for 1-D Linear Ultrasonic Phased Array Transducers

by Cheng Zou¹, Zhenguo Sun^1,2,*, Dong Cai¹, Salman Muhammad¹, Wenzeng Zhang¹ and Qiang Chen^1,2

¹ Department of Mechanical Engineering, Tsinghua University, Beijing 100084, China

² Yangtze Delta Region Institute of Tsinghua University, Jiaxing 314006, China

Sensors 2016, 16(11), 1873; https://doi.org/10.3390/s16111873 - 8 Nov 2016

Cited by 5 | Viewed by 5305

Abstract

A method is developed to accurately determine the spatial impulse response at the specifically discretized observation points in the radiated field of 1-D linear ultrasonic phased array transducers with great efficiency. In contrast, the previously adopted solutions only optimize the calculation procedure for [...] Read more.

A method is developed to accurately determine the spatial impulse response at the specifically discretized observation points in the radiated field of 1-D linear ultrasonic phased array transducers with great efficiency. In contrast, the previously adopted solutions only optimize the calculation procedure for a single rectangular transducer and required approximation considerations or nonlinear calculation. In this research, an algorithm that follows an alternative approach to expedite the calculation of the spatial impulse response of a rectangular linear array is presented. The key assumption for this algorithm is that the transducer apertures are identical and linearly distributed on an infinite rigid plane baffled with the same pitch. Two points in the observation field, which have the same position relative to two transducer apertures, share the same spatial impulse response that contributed from corresponding transducer, respectively. The observation field is discretized specifically to meet the relationship of equality. The analytical expressions of the proposed algorithm, based on the specific selection of the observation points, are derived to remove redundant calculations. In order to measure the proposed methodology, the simulation results obtained from the proposed method and the classical summation method are compared. The outcomes demonstrate that the proposed strategy can speed up the calculation procedure since it accelerates the speed-up ratio which relies upon the number of discrete points and the number of the array transducers. This development will be valuable in the development of advanced and faster linear ultrasonic phased array systems. Full article

(This article belongs to the Special Issue Ultrasonic Sensors)

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16 pages, 4078 KiB

Open AccessArticle

Novel N-Doped Carbon Dots/β-Cyclodextrin Nanocomposites for Enantioselective Recognition of Tryptophan Enantiomers

by Qi Xiao, Shuangyan Lu, Chusheng Huang, Wei Su and Shan Huang^*

College of Chemistry and Materials Science, Guangxi Teachers Education University, Nanning 530001, China

Sensors 2016, 16(11), 1874; https://doi.org/10.3390/s16111874 - 9 Nov 2016

Cited by 42 | Viewed by 8275

Abstract

Based on N-doped carbon dots/β-cyclodextrin nanocomposites modified glassy carbon electrodes (N-CDs/β-CD/GCE), an effective electrochemical sensor for enantioselective recognition of tryptophan (Trp) enantiomers was developed by differential pulse voltammograms (DPVs). Fluorescent N-CDs were synthesized through a hydrothermal method and characterized by spectroscopic approaches. The [...] Read more.

Based on N-doped carbon dots/β-cyclodextrin nanocomposites modified glassy carbon electrodes (N-CDs/β-CD/GCE), an effective electrochemical sensor for enantioselective recognition of tryptophan (Trp) enantiomers was developed by differential pulse voltammograms (DPVs). Fluorescent N-CDs were synthesized through a hydrothermal method and characterized by spectroscopic approaches. The N-CDs/β-CD nanocomposites were efficiently electrodeposited on the surface of GCE through C–N bond formation between N-CDs and electrode. The obtained N-CDs/β-CD/GCE was characterized by multispectroscopic and electrochemical methods. Such N-CDs/β-CD/GCE generated a significantly lower Ip and more negative Ep in the presence of l-Trp in DPVs, which was used for the enantioselective recognition of Trp enantiomers. The N-CDs/β-CD nanocomposites showed different binding constants for tryptophan enantiomers, and they further selectively bonded with l-Trp to form inclusion complexes. This N-CDs/β-CD/GCE combined advantages of N-CDs with strong C–N binding ability and β-CD with specific recognition of Trp enantiomers to fabricate a novel sensing platform for enantioselective recognition of Trp enantiomers. This strategy provided the possibility of using a nanostructured sensor to discriminate the chiral molecules in bio-electroanalytical applications. Full article

(This article belongs to the Special Issue Nanobiosensing for Sensors)

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19 pages, 5522 KiB

Open AccessArticle

A Selective Change Driven System for High-Speed Motion Analysis

by Jose A. Boluda^*

, Fernando Pardo and Francisco Vegara

Departament d’Informàtica, Escola Tècnica Superior d’Enginyeria, Universitat de València, Avd. de la Universidad, s/n, 46100 Burjassot, Spain

Sensors 2016, 16(11), 1875; https://doi.org/10.3390/s16111875 - 8 Nov 2016

Cited by 4 | Viewed by 5411

Abstract

Vision-based sensing algorithms are computationally-demanding tasks due to the large amount of data acquired and processed. Visual sensors deliver much information, even if data are redundant, and do not give any additional information. A Selective Change Driven (SCD) sensing system is based on [...] Read more.

Vision-based sensing algorithms are computationally-demanding tasks due to the large amount of data acquired and processed. Visual sensors deliver much information, even if data are redundant, and do not give any additional information. A Selective Change Driven (SCD) sensing system is based on a sensor that delivers, ordered by the magnitude of its change, only those pixels that have changed most since the last read-out. This allows the information stream to be adjusted to the computation capabilities. Following this strategy, a new SCD processing architecture for high-speed motion analysis, based on processing pixels instead of full frames, has been developed and implemented into a Field Programmable Gate-Array (FPGA). The programmable device controls the data stream, delivering a new object distance calculation for every new pixel. The acquisition, processing and delivery of a new object distance takes just 1.7

μ

s. Obtaining a similar result using a conventional frame-based camera would require a device working at roughly 500 Kfps, which is far from being practical or even feasible. This system, built with the recently-developed 64 × 64 CMOS SCD sensor, shows the potential of the SCD approach when combined with a hardware processing system. Full article

(This article belongs to the Special Issue Imaging: Sensors and Technologies)

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10 pages, 5652 KiB

Open AccessArticle

Enhanced Acetone Sensing Characteristics of ZnO/Graphene Composites

by Hao Zhang^1,2, Yuan Cen³, Yu Du^3,* and Shuangchen Ruan^1,*

¹ Shenzhen Key Laboratory of Laser Engineering, College of Optoelectronic Engineering, Shenzhen University, Shenzhen 518060, China

² Key Laboratory of Optoelectronic Devices and Systems of Ministry of Education and Guangdong Province, College of Optoelectronic Engineering, Shenzhen University, Shenzhen 518060, China

³ Shenzhen Key Laboratory of Sensor Technology, College of Physics Science and Technology, Shenzhen University, Shenzhen 518060, China

Sensors 2016, 16(11), 1876; https://doi.org/10.3390/s16111876 - 9 Nov 2016

Cited by 53 | Viewed by 8233

Abstract

ZnO/graphene (ZnO-G) hybrid composites are prepared via hydrothermal synthesis with graphite, N-methyl-pyrrolidone (NMP), and Zn(NO₃)₂·6H₂O as the precursors. The characterizations, including X-ray diffraction (XRD), thermogravimetric analyses (TGA), Raman spectroscopy, and transmission electron microscopy (TEM) indicate the formation [...] Read more.

ZnO/graphene (ZnO-G) hybrid composites are prepared via hydrothermal synthesis with graphite, N-methyl-pyrrolidone (NMP), and Zn(NO₃)₂·6H₂O as the precursors. The characterizations, including X-ray diffraction (XRD), thermogravimetric analyses (TGA), Raman spectroscopy, and transmission electron microscopy (TEM) indicate the formation of ZnO-G. Gas sensors were fabricated with ZnO-G composites and ZnO as sensing material, indicating that the response of the ZnO towards acetone was significantly enhanced by graphene doping. It was found that the ZnO-G sensor exhibits remarkably enhanced response of 13.3 at the optimal operating temperature of 280 °C to 100 ppm acetone, an improvement from 7.7 with pure ZnO. Full article

(This article belongs to the Special Issue Gas Nanosensors)

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15 pages, 4595 KiB

Open AccessArticle

A Laser-Based Measuring System for Online Quality Control of Car Engine Block

by Xing-Qiang Li

, Zhong Wang and Lu-Hua Fu^*

State Key Laboratory of Precision Measuring Technology and Instruments, Tianjin University, Tianjin 300072, China

Sensors 2016, 16(11), 1877; https://doi.org/10.3390/s16111877 - 8 Nov 2016

Cited by 30 | Viewed by 8241

Abstract

For online quality control of car engine production, pneumatic measurement instrument plays an unshakeable role in measuring diameters inside engine block because of its portability and high-accuracy. To the limitation of its measuring principle, however, the working space between the pneumatic device and [...] Read more.

For online quality control of car engine production, pneumatic measurement instrument plays an unshakeable role in measuring diameters inside engine block because of its portability and high-accuracy. To the limitation of its measuring principle, however, the working space between the pneumatic device and measured surface is too small to require manual operation. This lowers the measuring efficiency and becomes an obstacle to perform automatic measurement. In this article, a high-speed, automatic measuring system is proposed to take the place of pneumatic devices by using a laser-based measuring unit. The measuring unit is considered as a set of several measuring modules, where each of them acts like a single bore gauge and is made of four laser triangulation sensors (LTSs), which are installed on different positions and in opposite directions. The spatial relationship among these LTSs was calibrated before measurements. Sampling points from measured shaft holes can be collected by the measuring unit. A unified mathematical model was established for both calibration and measurement. Based on the established model, the relative pose between the measuring unit and measured workpiece does not impact the measuring accuracy. This frees the measuring unit from accurate positioning or adjustment, and makes it possible to realize fast and automatic measurement. The proposed system and method were finally validated by experiments. Full article

(This article belongs to the Section Physical Sensors)

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10 pages, 3181 KiB

Open AccessArticle

A Robust, Enzyme-Free Glucose Sensor Based on Lysine-Assisted CuO Nanostructures

by Qurrat-ul-Ain Baloach¹, Aneela Tahira¹, Arfana Begum Mallah¹, Muhammad Ishaq Abro², Siraj Uddin³, Magnus Willander^4,* and Zafar Hussain Ibupoto^1,*

¹ Kazi Institute of Chemistry, University of Sindh, Jamshoro 76080, Pakistan

² Department of Metallurgy and Material Science, Mehran University of Engineering and Technology, Jamshoro 76080, Pakistan

³ National Center of Excellence in Analytical Chemistry, University of Sindh, Jamshoro 76080, Pakistan

⁴ Department of Science and Technology, Campus Norrkoping, Linkoping University, Norrkoping SE-60174, Sweden

Sensors 2016, 16(11), 1878; https://doi.org/10.3390/s16111878 - 14 Nov 2016

Cited by 25 | Viewed by 6496

Abstract

The production of a nanomaterial with enhanced and desirable electrocatalytic properties is of prime importance, and the commercialization of devices containing these materials is a challenging task. In this study, unique cupric oxide (CuO) nanostructures were synthesized using lysine as a soft template [...] Read more.

The production of a nanomaterial with enhanced and desirable electrocatalytic properties is of prime importance, and the commercialization of devices containing these materials is a challenging task. In this study, unique cupric oxide (CuO) nanostructures were synthesized using lysine as a soft template for the evolution of morphology via a rapid and boiled hydrothermal method. The morphology and structure of the synthesized CuO nanomaterial were characterized using scanning electron microscopy (SEM) and X-ray diffraction (XRD), respectively. The prepared CuO nanostructures showed high potential for use in the electrocatalytic oxidation of glucose in an alkaline medium. The proposed enzyme-free glucose sensor demonstrated a robust response to glucose with a wide linear range and high sensitivity, selectivity, stability, and reproducibility. To explore its practical feasibility, the glucose content of serum samples was successfully determined using the enzyme-free sensor. An analytical recovery method was used to measure the actual glucose from the serum samples, and the results were satisfactory. Moreover, the presented glucose sensor has high chemical stability and can be reused for repetitive measurements. This study introduces an enzyme-free glucose sensor as an alternative tool for clinical glucose quantification. Full article

(This article belongs to the Special Issue Glucose Sensors: Revolution in Diabetes Management 2016)

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14 pages, 3888 KiB

Open AccessArticle

Fast and Inexpensive Detection of Bacterial Viability and Drug Effectiveness through Metabolic Monitoring

by Sondos Ayyash¹, Wen-I Wu² and Ponnambalam Ravi Selvaganapathy^1,2,*

¹ School of Biomedical Engineering, McMaster University, Hamilton, ON L8S 4K1, Canada

² Department of Mechanical Engineering, McMaster University, Hamilton, ON L8S 4L7, Canada

Sensors 2016, 16(11), 1879; https://doi.org/10.3390/s16111879 - 9 Nov 2016

Cited by 4 | Viewed by 5780

Abstract

Conventional methods for the detection of bacterial infection such as DNA or immunoassays are expensive, time consuming, or not definitive and thus may not provide all the information sought by medical professionals. In particular, it is difficult to obtain information about viability or [...] Read more.

Conventional methods for the detection of bacterial infection such as DNA or immunoassays are expensive, time consuming, or not definitive and thus may not provide all the information sought by medical professionals. In particular, it is difficult to obtain information about viability or drug effectiveness, which is crucial to formulate a treatment. Bacterial culture tests are the “gold standard” because they are inexpensive and do not require extensive sample preparation, and most importantly, provide all the necessary information sought by healthcare professionals, such as bacterial presence, viability and drug effectiveness. These conventional culture methods, however, have a long turnaround time, anywhere between 1 day and 4 weeks. Here, we solve this problem by monitoring the growth of bacteria in thousands of nanowells simultaneously to more quickly identify their presence in the sample and their viability. The segmentation of a sample with low bacterial concentration into thousands of nanoliter wells digitizes the samples and increases the effective concentration in those wells that contain bacteria. We monitor the metabolism of aerobic bacteria by using an oxygen-sensitive fluorophore, ruthenium tris (2,2’-diprydl) dichloride hexahydrate (RTDP), which allows us to monitor the dissolved oxygen concentration in the nanowells. Using E. coli K12 as a model pathogen, we demonstrate that the detection time of E. coli can be as fast as 35–60 min with sample concentrations varying from 10⁴ (62 min for detection), 10⁶ (42 min) and 10⁸ cells/mL (38 min). More importantly, we also demonstrate that reducing the well size can reduce the detection time. Finally we show that drug effectiveness information can be obtained in this format by loading the wells with the drug and monitoring the metabolism of the bacteria. The method that we have developed is low cost, simple, requires minimal sample preparation and can potentially be used with a wide variety of samples in a resource-poor setting to detect bacterial infections such as tuberculosis. Full article

(This article belongs to the Special Issue Biomicrofluidics)

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8 pages, 2405 KiB

Open AccessArticle

Organic Vapour Sensing Properties of Area-Ordered and Size-Controlled Silicon Nanopillar

by Wei Li^1,2,3,*, Zhilin Feng¹, Enwen Dai¹, Jie Xu¹ and Gang Bai^1,3,*

¹ State-Province Joint Engineering Laboratory for RF Integration and Micropackaging, College of Electronic Science and Engineering, Nanjing University of Posts and Telecommunications, Nanjing 210023, China

² State Key Laboratory of Electronic Thin Films and Integrated Devices, University of Electronic Science and Technology of China, Chengdu 610054, China

³ Laboratory of Solid State Microstructures, Nanjing University, Nanjing 210093, China

Sensors 2016, 16(11), 1880; https://doi.org/10.3390/s16111880 - 9 Nov 2016

Cited by 10 | Viewed by 5322

Abstract

Here, a silicon nanopillar array (Si-NPA) was fabricated. It was studied as a room-temperature organic vapour sensor, and the ethanol and acetone gas sensing properties were detected with I-V curves. I-V curves show that these Si-NPA gas sensors are sensitive to ethanol and [...] Read more.

Here, a silicon nanopillar array (Si-NPA) was fabricated. It was studied as a room-temperature organic vapour sensor, and the ethanol and acetone gas sensing properties were detected with I-V curves. I-V curves show that these Si-NPA gas sensors are sensitive to ethanol and acetone organic vapours. The turn-on threshold voltage is about 0.5 V and the operating voltage is 3 V. With 1% ethanol gas vapour, the response time is 5 s, and the recovery time is 15 s. Furthermore, an evaluation of the gas sensor stability for Si-NPA was performed. The gas stability results are acceptable for practical detections. These excellent sensing characteristics can mainly be attributed to the change of the overall dielectric constant of Si-NPA caused by the physisorption of gas molecules on the pillars, and the filling of the gas vapour in the voids. Full article

(This article belongs to the Section Chemical Sensors)

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15 pages, 5059 KiB

Open AccessArticle

The Impact of Sepiolite on Sensor Parameters during the Detection of Low Concentrations of Alcohols

by Patrycja Suchorska-Woźniak^*

, Olga Rac

, Marta Fiedot

and Helena Teterycz

Faculty of Microsystem Electronics and Photonics, Wrocław University of Science and Technology, Janiszewskiego 11/17, Wrocław 50-372, Poland

Sensors 2016, 16(11), 1881; https://doi.org/10.3390/s16111881 - 9 Nov 2016

Cited by 5 | Viewed by 5344

Abstract

The article presents the results of the detection of low-concentration C1–C4 alcohols using a planar sensor, in which a sepiolite filter was applied next to the gas-sensitive layer based on tin dioxide. The sepiolite layer is composed of tubes that have a length [...] Read more.

The article presents the results of the detection of low-concentration C1–C4 alcohols using a planar sensor, in which a sepiolite filter was applied next to the gas-sensitive layer based on tin dioxide. The sepiolite layer is composed of tubes that have a length of several microns, and the diameter of the single tube ranges from several to tens of nanometers. The sepiolite layer itself demonstrated no chemical activity in the presence of volatile organic compounds (VOC), and the passive filter made of this material did not modify the chemical composition of the gaseous atmosphere diffusing to the gas-sensitive layer. The test results revealed that the structural remodelling of the sepiolite that occurs under the influence of temperature, as well as the effect of the filter (a compound with ionic bonds) with molecules of water, has a significant impact on the improvement of the sensitivity of the sensor in relation to volatile organic compounds when compared to the sensor without a filter. Full article

(This article belongs to the Special Issue Gas Nanosensors)

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13 pages, 4813 KiB

Open AccessArticle

Determination Method of Bridge Rotation Angle Response Using MEMS IMU

by Hidehiko Sekiya^1,*, Takeshi Kinomoto² and Chitoshi Miki³

¹ Advanced Research Laboratories, Tokyo City University, 8-15-1 Todoroki, Setagaya 158-0082, Japan

² Maintenance and Transportation Division, Metropolitan Expressway Co., Ltd., 1-4-1 Kasumigaseki, Chiyoda-ku 100-8930, Japan

³ Tokyo City University, 1-28-1 Tamazutsumi, Setagaya 158-8557, Japan

Sensors 2016, 16(11), 1882; https://doi.org/10.3390/s16111882 - 9 Nov 2016

Cited by 15 | Viewed by 8234

Abstract

To implement steel bridge maintenance, especially that related to fatigue damage, it is important to monitor bridge deformations under traffic conditions. Bridges deform and rotate differently under traffic load conditions because their structures differ in terms of length and flexibility. Such monitoring enables [...] Read more.

To implement steel bridge maintenance, especially that related to fatigue damage, it is important to monitor bridge deformations under traffic conditions. Bridges deform and rotate differently under traffic load conditions because their structures differ in terms of length and flexibility. Such monitoring enables the identification of the cause of stress concentrations that cause fatigue damage and the proposal of appropriate countermeasures. However, although bridge deformation monitoring requires observations of bridge angle response as well as the bridge displacement response, measuring the rotation angle response of a bridge subject to traffic loads is difficult. Theoretically, the rotation angle response can be calculated by integrating the angular velocity, but for field measurements of actual in-service bridges, estimating the necessary boundary conditions would be difficult due to traffic-induced vibration. To solve the problem, this paper proposes a method for determining the rotation angle response of an in-service bridge from its angular velocity, as measured by a inertial measurement unit (IMU). To verify our proposed method, field measurements were conducted using nine micro-electrical mechanical systems (MEMS) IMUs and two contact displacement gauges. The results showed that our proposed method provided high accuracy when compared to the reference responses calculated by the contact displacement gauges. Full article

(This article belongs to the Collection Modeling, Testing and Reliability Issues in MEMS Engineering)

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22 pages, 4224 KiB

Open AccessArticle

The Ionospheric Scintillation Effects on the BeiDou Signal Receiver

by Zhijun He, Hongbo Zhao^*

and Wenquan Feng

School of Electronic and Information Engineering, Beihang University, Xueyuan Road No. 37, Haidian District, Beijing 100191, China

Sensors 2016, 16(11), 1883; https://doi.org/10.3390/s16111883 - 9 Nov 2016

Cited by 12 | Viewed by 5641

Abstract

Irregularities in the Earth’s ionosphere can make the amplitude and phase of radio signals fluctuate rapidly, which is known as ionospheric scintillation. Severe ionospheric scintillation could affect the performance of the Global Navigation Satellite System (GNSS). Currently, the Multiple Phase Screen (MPS) technique [...] Read more.

Irregularities in the Earth’s ionosphere can make the amplitude and phase of radio signals fluctuate rapidly, which is known as ionospheric scintillation. Severe ionospheric scintillation could affect the performance of the Global Navigation Satellite System (GNSS). Currently, the Multiple Phase Screen (MPS) technique is widely used in solving problems caused by weak and strong scintillations. Considering that Southern China is mainly located in the area where moderate and intense scintillation occur frequently, this paper built a model based on the MPS technique and discussed the scintillation impacts on China’s BeiDou navigation system. By using the BeiDou B1I signal, this paper analyzed the scintillation effects on the receiver, which includes the acquisition and tracking process. For acquisition process, this paper focused on the correlation peak and acquisition probability. For the tracking process, this paper focused on the carrier tracking loop and the code tracking loop. Simulation results show that under high scintillation intensity, the phase fluctuation could be −1.13 ± 0.087 rad to 1.40 ± 0.087 rad and the relative amplitude fluctuation could be −10 dB to 8 dB. As the scintillation intensity increased, the average correlation peak would decrease more than 8%, which could thus degrade acquisition performance. On the other hand, when the signal-to-noise ratio (SNR) is comparatively lower, the influence of strong scintillation on the phase locked loop (PLL) is much higher than that of weak scintillation. As the scintillation becomes more intense, PLL variance could consequently results in an error of more than 2.02 cm in carrier-phase based ranging. In addition, the delay locked loop (DLL) simulation results indicated that the pseudo-range error caused by strong scintillation could be more than 4 m and the consequent impact on positioning accuracy could be more than 6 m. Full article

(This article belongs to the Section Remote Sensors)

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17 pages, 3149 KiB

Open AccessArticle

Internet of Things Platform for Smart Farming: Experiences and Lessons Learnt

by Prem Prakash Jayaraman^1,*, Ali Yavari^2,3

, Dimitrios Georgakopoulos¹, Ahsan Morshed¹ and Arkady Zaslavsky²

¹ Department of Computer Science and Software Engineering, Swinburne University of Technology, Melbourne 3022, Australia

² Data 61, CSIRO, Melbourne 3168, Australia

³ Computer Science and Information Technology, RMIT University, Melbourne 3001, Australia

Sensors 2016, 16(11), 1884; https://doi.org/10.3390/s16111884 - 9 Nov 2016

Cited by 325 | Viewed by 29236

Abstract

Improving farm productivity is essential for increasing farm profitability and meeting the rapidly growing demand for food that is fuelled by rapid population growth across the world. Farm productivity can be increased by understanding and forecasting crop performance in a variety of environmental [...] Read more.

Improving farm productivity is essential for increasing farm profitability and meeting the rapidly growing demand for food that is fuelled by rapid population growth across the world. Farm productivity can be increased by understanding and forecasting crop performance in a variety of environmental conditions. Crop recommendation is currently based on data collected in field-based agricultural studies that capture crop performance under a variety of conditions (e.g., soil quality and environmental conditions). However, crop performance data collection is currently slow, as such crop studies are often undertaken in remote and distributed locations, and such data are typically collected manually. Furthermore, the quality of manually collected crop performance data is very low, because it does not take into account earlier conditions that have not been observed by the human operators but is essential to filter out collected data that will lead to invalid conclusions (e.g., solar radiation readings in the afternoon after even a short rain or overcast in the morning are invalid, and should not be used in assessing crop performance). Emerging Internet of Things (IoT) technologies, such as IoT devices (e.g., wireless sensor networks, network-connected weather stations, cameras, and smart phones) can be used to collate vast amount of environmental and crop performance data, ranging from time series data from sensors, to spatial data from cameras, to human observations collected and recorded via mobile smart phone applications. Such data can then be analysed to filter out invalid data and compute personalised crop recommendations for any specific farm. In this paper, we present the design of SmartFarmNet, an IoT-based platform that can automate the collection of environmental, soil, fertilisation, and irrigation data; automatically correlate such data and filter-out invalid data from the perspective of assessing crop performance; and compute crop forecasts and personalised crop recommendations for any particular farm. SmartFarmNet can integrate virtually any IoT device, including commercially available sensors, cameras, weather stations, etc., and store their data in the cloud for performance analysis and recommendations. An evaluation of the SmartFarmNet platform and our experiences and lessons learnt in developing this system concludes the paper. SmartFarmNet is the first and currently largest system in the world (in terms of the number of sensors attached, crops assessed, and users it supports) that provides crop performance analysis and recommendations. Full article

(This article belongs to the Special Issue Sensors for Agriculture)

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17 pages, 3261 KiB

Open AccessArticle

Highly Sensitive and Wide-Dynamic-Range Multichannel Optical-Fiber pH Sensor Based on PWM Technique

by Md. Rajibur Rahaman Khan

and Shin-Won Kang^*

School of Electronics Engineering, Kyungpook National University, 80 Daehakro, Bukgu, Daegu 41566, Korea

Sensors 2016, 16(11), 1885; https://doi.org/10.3390/s16111885 - 9 Nov 2016

Cited by 13 | Viewed by 7979

Abstract

In this study, we propose a highly sensitive multichannel pH sensor that is based on an optical-fiber pulse width modulation (PWM) technique. According to the optical-fiber PWM method, the received sensing signal’s pulse width changes when the optical-fiber pH sensing-element of the array [...] Read more.

In this study, we propose a highly sensitive multichannel pH sensor that is based on an optical-fiber pulse width modulation (PWM) technique. According to the optical-fiber PWM method, the received sensing signal’s pulse width changes when the optical-fiber pH sensing-element of the array comes into contact with pH buffer solutions. The proposed optical-fiber PWM pH-sensing system offers a linear sensing response over a wide range of pH values from 2 to 12, with a high pH-sensing ability. The sensitivity of the proposed pH sensor is 0.46 µs/pH, and the correlation coefficient R² is approximately 0.997. Additional advantages of the proposed optical-fiber PWM pH sensor include a short/fast response-time of about 8 s, good reproducibility properties with a relative standard deviation (RSD) of about 0.019, easy fabrication, low cost, small size, reusability of the optical-fiber sensing-element, and the capability of remote sensing. Finally, the performance of the proposed PWM pH sensor was compared with that of potentiometric, optical-fiber modal interferometer, and optical-fiber Fabry–Perot interferometer pH sensors with respect to dynamic range width, linearity as well as response and recovery times. We observed that the proposed sensing systems have better sensing abilities than the above-mentioned pH sensors. Full article

(This article belongs to the Section Chemical Sensors)

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8 pages, 4771 KiB

Open AccessArticle

Wide-Spectrum Microscope with a Long Working Distance Aspherical Objective Based on Obscuration Constraint

by Weibo Wang^1,2,*

, Chao Wang^1,*, Jian Liu¹ and Jiubin Tan¹

¹ Institute of Ultra-Precision Optoelectronic Instrument Engineering, Harbin Institute of Technology, Harbin 150001, China

² Department of Engineering Science, University of Oxford, ParksRoad, Oxford OX1 3PJ, UK

Sensors 2016, 16(11), 1886; https://doi.org/10.3390/s16111886 - 9 Nov 2016

Cited by 3 | Viewed by 6194

Abstract

We present an approach for an initial configuration design based on obscuration constraint and on-axis Taylor series expansion to realize the design of long working distance microscope (numerical aperture (NA) = 0.13 and working distance (WD) = 525 mm) with a low obscuration [...] Read more.

We present an approach for an initial configuration design based on obscuration constraint and on-axis Taylor series expansion to realize the design of long working distance microscope (numerical aperture (NA) = 0.13 and working distance (WD) = 525 mm) with a low obscuration aspherical Schwarzschild objective in wide-spectrum imaging (λ = 400–900 nm). Experiments of the testing on the resolution target and inspection on United States Air Force (USAF) resolution chart and a line charge-coupled device (CCD) (pixel size of 14 μm × 56 μm) with different wavelength light sources (λ = 480 nm, 550 nm, 660 nm, 850 nm) were implemented to verify the validity of the proposed method. Full article

(This article belongs to the Section Physical Sensors)

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19 pages, 3839 KiB

Open AccessArticle

Mechanical Fault Diagnosis of High Voltage Circuit Breakers Based on Variational Mode Decomposition and Multi-Layer Classifier

by Nantian Huang^1,*, Huaijin Chen¹

, Guowei Cai¹, Lihua Fang¹ and Yuqiang Wang²

¹ School of Electrical Engineering, Northeast Electric Power University, Jilin 132012, China

² State Grid Jibei Electric Power Co., Ltd. Maintenance Branch, Beijing 102488, China

Sensors 2016, 16(11), 1887; https://doi.org/10.3390/s16111887 - 10 Nov 2016

Cited by 84 | Viewed by 7008

Abstract

Mechanical fault diagnosis of high-voltage circuit breakers (HVCBs) based on vibration signal analysis is one of the most significant issues in improving the reliability and reducing the outage cost for power systems. The limitation of training samples and types of machine faults in [...] Read more.

Mechanical fault diagnosis of high-voltage circuit breakers (HVCBs) based on vibration signal analysis is one of the most significant issues in improving the reliability and reducing the outage cost for power systems. The limitation of training samples and types of machine faults in HVCBs causes the existing mechanical fault diagnostic methods to recognize new types of machine faults easily without training samples as either a normal condition or a wrong fault type. A new mechanical fault diagnosis method for HVCBs based on variational mode decomposition (VMD) and multi-layer classifier (MLC) is proposed to improve the accuracy of fault diagnosis. First, HVCB vibration signals during operation are measured using an acceleration sensor. Second, a VMD algorithm is used to decompose the vibration signals into several intrinsic mode functions (IMFs). The IMF matrix is divided into submatrices to compute the local singular values (LSV). The maximum singular values of each submatrix are selected as the feature vectors for fault diagnosis. Finally, a MLC composed of two one-class support vector machines (OCSVMs) and a support vector machine (SVM) is constructed to identify the fault type. Two layers of independent OCSVM are adopted to distinguish normal or fault conditions with known or unknown fault types, respectively. On this basis, SVM recognizes the specific fault type. Real diagnostic experiments are conducted with a real SF₆ HVCB with normal and fault states. Three different faults (i.e., jam fault of the iron core, looseness of the base screw, and poor lubrication of the connecting lever) are simulated in a field experiment on a real HVCB to test the feasibility of the proposed method. Results show that the classification accuracy of the new method is superior to other traditional methods. Full article

(This article belongs to the Section Physical Sensors)

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14 pages, 2716 KiB

Open AccessArticle

Colorimetric Analysis of Ochratoxin A in Beverage Samples

by Diana Bueno^1,2, Luis F. Valdez¹

, Juan Manuel Gutiérrez Salgado¹

, Jean Louis Marty² and Roberto Muñoz^1,*

¹ Bioelectronics Section, Department of Electrical Engineering, CINVESTAV-IPN, Mexico City 07360, Mexico

² Université de Perpignan Via Domitia, BAE, Building S 52 Av. Paul Alduy, Perpignan Cedex 66860, France

Sensors 2016, 16(11), 1888; https://doi.org/10.3390/s16111888 - 10 Nov 2016

Cited by 17 | Viewed by 7006

Abstract

This manuscript describes the use of a portable and low cost fluorescence setup to quantify the concentration of ochratoxin A (OTA) in beverage samples using an in-house developed system and different color models. It is reported that OTA is naturally fluorescent, for that [...] Read more.

This manuscript describes the use of a portable and low cost fluorescence setup to quantify the concentration of ochratoxin A (OTA) in beverage samples using an in-house developed system and different color models. It is reported that OTA is naturally fluorescent, for that reason an ultraviolet light at 365 nm was used to excite the samples and a Complementary Metal Oxide Semiconductor (CMOS) sensor was used to get a photograph of the OTA under excitation conditions, which is controlled by an executable interface designed in MATLAB. For each concentration of OTA, the coordinates with respect to each model color were obtained and plotted to quantify the mycotoxin present in the sample. It was possible to observe that despite the fact no extraction column was employed, the Red, Green, Blue (RGB) model shows a proportional relation to the evaluated concentrations. Despite the fact more analysis and other methods are required to quantify the OTA concentration, the brightness and a,b for the color-opponent dimensions (L*a*b) and Hue, Saturation, Value (HSV) tests provide results whereby it is possible to identify the concentration of OTA in beverage samples such as beer and wine. Full article

(This article belongs to the Special Issue Olfactory and Gustatory Sensors)

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15 pages, 4327 KiB

Open AccessArticle

Investigation of Gas-Sensing Property of Acid-Deposited Polyaniline Thin-Film Sensors for Detecting H₂S and SO₂

by Xingchen Dong¹, Xiaoxing Zhang^1,2,*, Xiaoqing Wu³, Hao Cui¹ and Dachang Chen²

¹ State Key Laboratory of Power Transmission Equipment & System Security and New Technology, Chongqing University, Chongqing 400044, China

² School of Electrical Engineering, Wuhan University, Wuhan 430072, China

³ Fuyang Power Supply Company, State Grid Anhui Electric Power Company, Fuyang 236000, China

Sensors 2016, 16(11), 1889; https://doi.org/10.3390/s16111889 - 10 Nov 2016

Cited by 20 | Viewed by 5386

Abstract

Latent insulation defects introduced in manufacturing process of gas-insulated switchgears can lead to partial discharge during long-time operation, even to insulation fault if partial discharge develops further. Monitoring of decomposed components of SF₆, insulating medium of gas-insulated switchgear, is a feasible [...] Read more.

Latent insulation defects introduced in manufacturing process of gas-insulated switchgears can lead to partial discharge during long-time operation, even to insulation fault if partial discharge develops further. Monitoring of decomposed components of SF₆, insulating medium of gas-insulated switchgear, is a feasible method of early-warning to avoid the occurrence of sudden fault. Polyaniline thin-film with protonic acid deposited possesses wide application prospects in the gas-sensing field. Polyaniline thin-film sensors with only sulfosalicylic acid deposited and with both hydrochloric acid and sulfosalicylic acid deposited were prepared by chemical oxidative polymerization method. Gas-sensing experiment was carried out to test properties of new sensors when exposed to H₂S and SO₂, two decomposed products of SF₆ under discharge. The gas-sensing properties of these two sensors were compared with that of a hydrochloric acid deposited sensor. Results show that the hydrochloric acid and sulfosalicylic acid deposited polyaniline thin-film sensor shows the most outstanding sensitivity and selectivity to H₂S and SO₂ when concentration of gases range from 10 to 100 μL/L, with sensitivity changing linearly with concentration of gases. The sensor also possesses excellent long-time and thermal stability. This research lays the foundation for preparing practical gas-sensing devices to detect H₂S and SO₂ in gas-insulated switchgears at room temperature. Full article

(This article belongs to the Section Physical Sensors)

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14 pages, 1448 KiB

Open AccessArticle

Robust Approach for Nonuniformity Correction in Infrared Focal Plane Array

by Ayoub Boutemedjet

, Chenwei Deng^*

and Baojun Zhao

School of Information and Electronics, Beijing Institute of Technology, Beijing 100081, China

Sensors 2016, 16(11), 1890; https://doi.org/10.3390/s16111890 - 10 Nov 2016

Cited by 16 | Viewed by 5350

Abstract

In this paper, we propose a new scene-based nonuniformity correction technique for infrared focal plane arrays. Our work is based on the use of two well-known scene-based methods, namely, adaptive and interframe registration-based exploiting pure translation motion model between frames. The two approaches [...] Read more.

In this paper, we propose a new scene-based nonuniformity correction technique for infrared focal plane arrays. Our work is based on the use of two well-known scene-based methods, namely, adaptive and interframe registration-based exploiting pure translation motion model between frames. The two approaches have their benefits and drawbacks, which make them extremely effective in certain conditions and not adapted for others. Following on that, we developed a method robust to various conditions, which may slow or affect the correction process by elaborating a decision criterion that adapts the process to the most effective technique to ensure fast and reliable correction. In addition to that, problems such as bad pixels and ghosting artifacts are also dealt with to enhance the overall quality of the correction. The performance of the proposed technique is investigated and compared to the two state-of-the-art techniques cited above. Full article

(This article belongs to the Section Physical Sensors)

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16 pages, 3292 KiB

Open AccessArticle

Development of an Exhaled Breath Monitoring System with Semiconductive Gas Sensors, a Gas Condenser Unit, and Gas Chromatograph Columns

by Toshio Itoh^1,*, Toshio Miwa¹, Akihiro Tsuruta¹, Takafumi Akamatsu¹, Noriya Izu¹, Woosuck Shin¹, Jangchul Park², Toyoaki Hida², Takeshi Eda³ and Yasuhiro Setoguchi³

¹ National Institute of Advanced Industrial Science and Technology (AIST), Shimo-Shidami, Moriyama-ku, Nagoya 463-8560, Japan

² Aichi Cancer Center, 1-1 Kanokoden, Chikusa-ku, Nagoya 464-8681, Japan

³ Figaro Engineering Inc., 1-5-11 Sembanishi, Minoh, Osaka 562-8505, Japan

Sensors 2016, 16(11), 1891; https://doi.org/10.3390/s16111891 - 10 Nov 2016

Cited by 66 | Viewed by 7613

Abstract

Various volatile organic compounds (VOCs) in breath exhaled by patients with lung cancer, healthy controls, and patients with lung cancer who underwent surgery for resection of cancer were analyzed by gas condenser-equipped gas chromatography-mass spectrometry (GC/MS) for development of an exhaled breath monitoring [...] Read more.

Various volatile organic compounds (VOCs) in breath exhaled by patients with lung cancer, healthy controls, and patients with lung cancer who underwent surgery for resection of cancer were analyzed by gas condenser-equipped gas chromatography-mass spectrometry (GC/MS) for development of an exhaled breath monitoring prototype system involving metal oxide gas sensors, a gas condenser, and gas chromatography columns. The gas condenser-GC/MS analysis identified concentrations of 56 VOCs in the breath exhaled by the test population of 136 volunteers (107 patients with lung cancer and 29 controls), and selected four target VOCs, nonanal, acetoin, acetic acid, and propanoic acid, for use with the condenser, GC, and sensor-type prototype system. The prototype system analyzed exhaled breath samples from 101 volunteers (74 patients with lung cancer and 27 controls). The prototype system exhibited a level of performance similar to that of the gas condenser-GC/MS system for breath analysis. Full article

(This article belongs to the Special Issue Gas Sensors for Health Care and Medical Applications)

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22 pages, 4121 KiB

Open AccessArticle

Traffic Management for Emergency Vehicle Priority Based on Visual Sensing

by Kapileswar Nellore^1,*

and Gerhard P. Hancke^1,2

¹ Department of Electrical, Electronic and Computer Engineering, University of Pretoria, Pretoria 0028, South Africa

² Department of Computer Science, City University of Hong Kong, Hong Kong, China

Sensors 2016, 16(11), 1892; https://doi.org/10.3390/s16111892 - 10 Nov 2016

Cited by 126 | Viewed by 21928

Abstract

Vehicular traffic is endlessly increasing everywhere in the world and can cause terrible traffic congestion at intersections. Most of the traffic lights today feature a fixed green light sequence, therefore the green light sequence is determined without taking the presence of the emergency [...] Read more.

Vehicular traffic is endlessly increasing everywhere in the world and can cause terrible traffic congestion at intersections. Most of the traffic lights today feature a fixed green light sequence, therefore the green light sequence is determined without taking the presence of the emergency vehicles into account. Therefore, emergency vehicles such as ambulances, police cars, fire engines, etc. stuck in a traffic jam and delayed in reaching their destination can lead to loss of property and valuable lives. This paper presents an approach to schedule emergency vehicles in traffic. The approach combines the measurement of the distance between the emergency vehicle and an intersection using visual sensing methods, vehicle counting and time sensitive alert transmission within the sensor network. The distance between the emergency vehicle and the intersection is calculated for comparison using Euclidean distance, Manhattan distance and Canberra distance techniques. The experimental results have shown that the Euclidean distance outperforms other distance measurement techniques. Along with visual sensing techniques to collect emergency vehicle information, it is very important to have a Medium Access Control (MAC) protocol to deliver the emergency vehicle information to the Traffic Management Center (TMC) with less delay. Then only the emergency vehicle is quickly served and can reach the destination in time. In this paper, we have also investigated the MAC layer in WSNs to prioritize the emergency vehicle data and to reduce the transmission delay for emergency messages. We have modified the medium access procedure used in standard IEEE 802.11p with PE-MAC protocol, which is a new back off selection and contention window adjustment scheme to achieve low broadcast delay for emergency messages. A VANET model for the UTMS is developed and simulated in NS-2. The performance of the standard IEEE 802.11p and the proposed PE-MAC is analysed in detail. The NS-2 simulation results have shown that the PE-MAC outperforms the IEEE 802.11p in terms of average end-to-end delay, throughput and energy consumption. The performance evaluation results have proven that the proposed PE-MAC prioritizes the emergency vehicle data and delivers the emergency messages to the TMC with less delay compared to the IEEE 802.11p. The transmission delay of the proposed PE-MAC is also compared with the standard IEEE 802.15.4, and Enhanced Back-off Selection scheme for IEEE 802.15.4 protocol [EBSS, an existing protocol to ensure fast transmission of the detected events on the road towards the TMC] and the comparative results have proven the effectiveness of the PE-MAC over them. Furthermore, this research work will provide an insight into the design of an intelligent urban traffic management system for the effective management of emergency vehicles and will help to save lives and property. Full article

(This article belongs to the Special Issue Vehicular Sensor Networks: Technical Challenges, Supports, and Application Experiences)

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9 pages, 7582 KiB

Open AccessArticle

Influence of PZT Coating Thickness and Electrical Pole Alignment on Microresonator Properties

by Giedrius Janusas¹

, Sigita Ponelyte^1,*, Alfredas Brunius¹, Asta Guobiene², Andrius Vilkauskas¹ and Arvydas Palevicius¹

¹ Faculty of Mechanical Engineering and Design, Kaunas University of Technology, Studentu str. 56, Kaunas LT-51424, Lithuania

² Institute of Materials Science, Kaunas University of Technology, Barsausko str. 59, Kaunas LT-51423, Lithuania

Sensors 2016, 16(11), 1893; https://doi.org/10.3390/s16111893 - 10 Nov 2016

Cited by 14 | Viewed by 5078

Abstract

With increasing technical requirements in the design of microresonators, the development of new techniques for lightweight, simple, and inexpensive components becomes relevant. Lead zirconate titanate (PZT) is a powerful tool in the formation of these components, allowing a self-actuation or self-sensing capability. Different [...] Read more.

With increasing technical requirements in the design of microresonators, the development of new techniques for lightweight, simple, and inexpensive components becomes relevant. Lead zirconate titanate (PZT) is a powerful tool in the formation of these components, allowing a self-actuation or self-sensing capability. Different fabrication methods lead to the variation of the properties of the device itself. This research paper covers the fabrication of a novel PZT film and the investigations of its chemical, surface, and dynamic properties when film thickness is varied. A screen-printing technique was used for the formation of smooth films of 60 µm, 68 µm, and 25 µm thickness. A custom-made poling technique was applied to enhance the piezoelectric properties of the designed films. However, poling did not change any compositional or surface characteristics of the films; changes were only seen in the electrical ones. The results showed that a thinner poled PZT film having a chemical composition with the highest amount of copper and zirconium led to better electrical characteristics (generated voltage of 3.5 mV). Full article

(This article belongs to the Section Physical Sensors)

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13 pages, 4926 KiB

Open AccessArticle

Miniaturized and Wireless Optical Neurotransmitter Sensor for Real-Time Monitoring of Dopamine in the Brain

by Min H. Kim¹, Hargsoon Yoon^1,2,*, Sang H. Choi³, Fei Zhao⁴, Jongsung Kim⁴, Kyo D. Song^1,2 and Uhn Lee⁵

¹ Center for Materials Research, Norfolk State University, Norfolk, VA 23504, USA

² Neural Engineering and Nano Electronics Laboratory, Department of Engineering, Norfolk State University, Norfolk, VA 23504, USA

³ NASA Langley Research Center, Hampton, VA 23681, USA

⁴ Department of Chemical and Biological Engineering, Gachon University, Seongnam 13120, Korea

⁵ Department of Neurosurgery, Gachon University of Medicine and Science, Incheon 21936, Korea

Sensors 2016, 16(11), 1894; https://doi.org/10.3390/s16111894 - 10 Nov 2016

Cited by 18 | Viewed by 7041

Abstract

Real-time monitoring of extracellular neurotransmitter concentration offers great benefits for diagnosis and treatment of neurological disorders and diseases. This paper presents the study design and results of a miniaturized and wireless optical neurotransmitter sensor (MWONS) for real-time monitoring of brain dopamine concentration. MWONS [...] Read more.

Real-time monitoring of extracellular neurotransmitter concentration offers great benefits for diagnosis and treatment of neurological disorders and diseases. This paper presents the study design and results of a miniaturized and wireless optical neurotransmitter sensor (MWONS) for real-time monitoring of brain dopamine concentration. MWONS is based on fluorescent sensing principles and comprises a microspectrometer unit, a microcontroller for data acquisition, and a Bluetooth wireless network for real-time monitoring. MWONS has a custom-designed application software that controls the operation parameters for excitation light sources, data acquisition, and signal processing. MWONS successfully demonstrated a measurement capability with a limit of detection down to a 100 nanomole dopamine concentration, and high selectivity to ascorbic acid (90:1) and uric acid (36:1). Full article

(This article belongs to the Section Biosensors)

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13 pages, 3344 KiB

Open AccessArticle

A Data Transfer Fusion Method for Discriminating Similar Spectral Classes

by Qingyan Wang^*

and Junping Zhang

Harbin Institute of Technology, School of Electronics and Information Engineering, Harbin 150001, China

Sensors 2016, 16(11), 1895; https://doi.org/10.3390/s16111895 - 14 Nov 2016

Cited by 3 | Viewed by 4096

Abstract

Hyperspectral data provide new capabilities for discriminating spectrally similar classes, but such class signatures sometimes will be difficult to analyze. To incorporate reliable useful information could help, but at the same time, may also lead increased dimensionality of the feature vector making the [...] Read more.

Hyperspectral data provide new capabilities for discriminating spectrally similar classes, but such class signatures sometimes will be difficult to analyze. To incorporate reliable useful information could help, but at the same time, may also lead increased dimensionality of the feature vector making the hyperspectral data larger than expected. It is challenging to apply discriminative information from these training data to testing data that are not in the same feature space and with different data distributions. A data fusion method based on transfer learning is proposed, in which transfer learning is introduced into boosting algorithm, and other out-date data are used to instruct hyperspectral image classification. In order to validate the method, experiments are conducted on EO-1 Hyperion hyperspectral data and ROSIS hyperspectral data. Significant improvements have been achieved in terms of accuracy compared to the results generated by conventional classification approaches. Full article

(This article belongs to the Special Issue Precision Agriculture and Remote Sensing Data Fusion)

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15 pages, 8775 KiB

Open AccessArticle

On Gait Analysis Estimation Errors Using Force Sensors on a Smart Rollator

by Joaquin Ballesteros^1,*,†,‡

, Cristina Urdiales^1,‡

, Antonio B. Martinez^2,‡ and Jaap H. Van Dieën^3,‡

¹ Department of Electronic Technology, University of Malaga, 29071 Malaga, Spain

² Department of Automatic Control, Polytechnic University of Catalonia, 08034 Barcelona, Spain

³ MOVE Research Institute Amsterdam, Department of Human Movement Sciences, Vrije Universiteit Amsterdam, 1081 BT Amsterdam, The Netherlands

^† Current address: ETSI Telecomunicacion, Campus de Teatinos, 29071 Malaga, Spain.

^‡ These authors contributed equally to this work.

Sensors 2016, 16(11), 1896; https://doi.org/10.3390/s16111896 - 10 Nov 2016

Cited by 14 | Viewed by 6663

Abstract

Gait analysis can provide valuable information on a person’s condition and rehabilitation progress. Gait is typically captured using external equipment and/or wearable sensors. These tests are largely constrained to specific controlled environments. In addition, gait analysis often requires experts for calibration, operation and/or [...] Read more.

Gait analysis can provide valuable information on a person’s condition and rehabilitation progress. Gait is typically captured using external equipment and/or wearable sensors. These tests are largely constrained to specific controlled environments. In addition, gait analysis often requires experts for calibration, operation and/or to place sensors on volunteers. Alternatively, mobility support devices like rollators can be equipped with onboard sensors to monitor gait parameters, while users perform their Activities of Daily Living. Gait analysis in rollators may use odometry and force sensors in the handlebars. However, force based estimation of gait parameters is less accurate than traditional methods, especially when rollators are not properly used. This paper presents an evaluation of force based gait analysis using a smart rollator on different groups of users to determine when this methodology is applicable. In a second stage, the rollator is used in combination with two lab-based gait analysis systems to assess the rollator estimation error. Our results show that: (i) there is an inverse relation between the variance in the force difference between handlebars and support on the handlebars—related to the user condition—and the estimation error; and (ii) this error is lower than 10% when the variation in the force difference is above 7 N. This lower limit was exceeded by the 95.83% of our challenged volunteers. In conclusion, rollators are useful for gait characterization as long as users really need the device for ambulation. Full article

(This article belongs to the Special Issue State-of-the-Art Sensors Technology in Spain 2016)

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14 pages, 6810 KiB

Open AccessArticle

Tip-Clearance Measurement in the First Stage of the Compressor of an Aircraft Engine

by Iker García^1,*

, Radosław Przysowa²

, Josu Amorebieta¹ and Joseba Zubia¹

¹ Department of Communications Engineering, Engineering School of Bilbao, University of the Basque Country UPV/EHU, Alda. Urquijo s/n E-48013 Bilbao, Spain

² Air Force Institute of Technology (Instytut Techniczny Wojsk Lotniczych), ul. Ksiecia Boleslawa 6 01-494 Warszawa, Poland

Sensors 2016, 16(11), 1897; https://doi.org/10.3390/s16111897 - 11 Nov 2016

Cited by 31 | Viewed by 7296

Abstract

In this article, we report the design of a reflective intensity-modulated optical fiber sensor for blade tip-clearance measurement, and the experimental results for the first stage of a compressor of an aircraft engine operating in real conditions. The tests were performed in a [...] Read more.

In this article, we report the design of a reflective intensity-modulated optical fiber sensor for blade tip-clearance measurement, and the experimental results for the first stage of a compressor of an aircraft engine operating in real conditions. The tests were performed in a ground test cell, where the engine completed four cycles from idling state to takeoff and back to idling state. During these tests, the rotational speed of the compressor ranged between 7000 and 15,600 rpm. The main component of the sensor is a tetrafurcated bundle of optical fibers, with which the resulting precision of the experimental measurements was 12 µm for a measurement range from 2 to 4 mm. To get this precision the effect of temperature on the optoelectronic components of the sensor was compensated by calibrating the sensor in a climate chamber. A custom-designed MATLAB program was employed to simulate the behavior of the sensor prior to its manufacture. Full article

(This article belongs to the Special Issue Optical Fiber Sensors 2016)

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19 pages, 7502 KiB

Open AccessArticle

Indoor Location Sensing with Invariant Wi-Fi Received Signal Strength Fingerprinting

by Mohd Nizam Husen

and Sukhan Lee^*

Intelligent Systems Research Institute, Sungkyunkwan University, Suwon, Gyeonggi-do 440-746, Korea

Sensors 2016, 16(11), 1898; https://doi.org/10.3390/s16111898 - 11 Nov 2016

Cited by 33 | Viewed by 7187

Abstract

A method of location fingerprinting based on the Wi-Fi received signal strength (RSS) in an indoor environment is presented. The method aims to overcome the RSS instability due to varying channel disturbances in time by introducing the concept of invariant RSS statistics. The [...] Read more.

A method of location fingerprinting based on the Wi-Fi received signal strength (RSS) in an indoor environment is presented. The method aims to overcome the RSS instability due to varying channel disturbances in time by introducing the concept of invariant RSS statistics. The invariant RSS statistics represent here the RSS distributions collected at individual calibration locations under minimal random spatiotemporal disturbances in time. The invariant RSS statistics thus collected serve as the reference pattern classes for fingerprinting. Fingerprinting is carried out at an unknown location by identifying the reference pattern class that maximally supports the spontaneous RSS sensed from individual Wi-Fi sources. A design guideline is also presented as a rule of thumb for estimating the number of Wi-Fi signal sources required to be available for any given number of calibration locations under a certain level of random spatiotemporal disturbances. Experimental results show that the proposed method not only provides 17% higher success rate than conventional ones but also removes the need for recalibration. Furthermore, the resolution is shown finer by 40% with the execution time more than an order of magnitude faster than the conventional methods. These results are also backed up by theoretical analysis. Full article

(This article belongs to the Section Sensor Networks)

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15 pages, 4325 KiB

Open AccessArticle

A Digital Lock-In Amplifier for Use at Temperatures of up to 200 °C

by Jingjing Cheng¹, Yingjun Xu¹, Lei Wu^2,* and Guangwei Wang³

¹ School of Automation, Huazhong University of Science and Technology, Wuhan 430074, China

² School of Chemical Engineering and Environment, Beijing Institute of Technology, Beijing 100000, China

³ Well-Tech R&D Institutes, China Oilfield Service Limited, Beijing 101149, China

Sensors 2016, 16(11), 1899; https://doi.org/10.3390/s16111899 - 11 Nov 2016

Cited by 12 | Viewed by 8932

Abstract

Weak voltage signals cannot be reliably measured using currently available logging tools when these tools are subject to high-temperature (up to 200 °C) environments for prolonged periods. In this paper, we present a digital lock-in amplifier (DLIA) capable of operating at temperatures of [...] Read more.

Weak voltage signals cannot be reliably measured using currently available logging tools when these tools are subject to high-temperature (up to 200 °C) environments for prolonged periods. In this paper, we present a digital lock-in amplifier (DLIA) capable of operating at temperatures of up to 200 °C. The DLIA contains a low-noise instrument amplifier and signal acquisition and the corresponding signal processing electronics. The high-temperature stability of the DLIA is achieved by designing system-in-package (SiP) and multi-chip module (MCM) components with low thermal resistances. An effective look-up-table (LUT) method was developed for the lock-in amplifier algorithm, to decrease the complexity of the calculations and generate less heat than the traditional way. The performance of the design was tested by determining the linearity, gain, Q value, and frequency characteristic of the DLIA between 25 and 200 °C. The maximal nonlinear error in the linearity of the DLIA working at 200 °C was about 1.736% when the equivalent input was a sine wave signal with an amplitude of between 94.8 and 1896.0 nV and a frequency of 800 kHz. The tests showed that the DLIA proposed could work effectively in high-temperature environments up to 200 °C. Full article

(This article belongs to the Section Physical Sensors)

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12 pages, 3525 KiB

Open AccessArticle

A Novel Application for Low Frequency Electrochemical Impedance Spectroscopy as an Online Process Monitoring Tool for Viable Cell Concentrations

by Christoph Slouka^1,4,*

, David J. Wurm¹, Georg Brunauer²

, Andreas Welzl-Wachter³, Oliver Spadiut^1,4

, Jürgen Fleig³ and Christoph Herwig^1,4

¹ Research Division Biochemical Engineering, Institute of Chemical Engineering, Vienna University of Technology, Vienna 1060, Austria

² Institute for Energy Systems and Thermodynamics, Vienna University of Technology, Vienna 1060, Austria

³ Research Division Electrochemistry, Institute of Chemical Technology and Analytics, Vienna University of Technology, Vienna 1060, Austria

⁴ Christian Doppler Laboratory for Mechanistic and Physiological Methods for Improved Bioprocesses, Institute of Chemical Engineering, Vienna University of Technology, Vienna 1060, Austria

Sensors 2016, 16(11), 1900; https://doi.org/10.3390/s16111900 - 11 Nov 2016

Cited by 23 | Viewed by 9514

Abstract

New approaches in process monitoring during industrial fermentations are not only limited to classical pH, dO₂ and offgas analysis, but use different in situ and online sensors based on different physical principles to determine biomass, product quality, lysis and far more. One [...] Read more.

New approaches in process monitoring during industrial fermentations are not only limited to classical pH, dO₂ and offgas analysis, but use different in situ and online sensors based on different physical principles to determine biomass, product quality, lysis and far more. One of the very important approaches is the in situ accessibility of viable cell concentration (VCC). This knowledge provides increased efficiency in monitoring and controlling strategies during cultivations. Electrochemical impedance spectroscopy—EIS—is used to monitor biomass in a fermentation of E. coli BL21(DE3), producing a recombinant protein using a fed batch-based approach. Increases in the double layer capacitance (C_dl), determined at frequencies below 1 kHz, are proportional to the increase of biomass in the batch and fed batch phase, monitored in offline and online modes for different cultivations. A good correlation of C_dl with cell density is found and in order to get an appropriate verification of this method, different state-of-the-art biomass measurements are performed and compared. Since measurements in this frequency range are largely determined by the double layer region between the electrode and media, rather minor interferences with process parameters (aeration, stirring) are to be expected. It is shown that impedance spectroscopy at low frequencies is a powerful tool for cultivation monitoring. Full article

(This article belongs to the Section Biosensors)

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13 pages, 1738 KiB

Open AccessArticle

Electrochemical Aptatoxisensor Responses on Nanocomposites Containing Electro-Deposited Silver Nanoparticles on Poly(Propyleneimine) Dendrimer for the Detection of Microcystin-LR in Freshwater

by Mawethu P. Bilibana¹, Avril R. Williams², Candice Rassie¹, Christopher E. Sunday¹, Hlamulo Makelane¹, Lindsay Wilson¹, Nomaphelo Ntshongontshi¹, Abongile N. Jijana¹, Milua Masikini¹, Priscilla G. L. Baker¹ and Emmanuel I. Iwuoha^1,*

¹ SensorLab, Department of Chemistry, University of Western Cape, Robert Sobukwe Road, Bellville, Cape Town 7535, South Africa

² Department of Biological and Chemical Sciences, The University of the West Indies, Cave Hill, St. Michael BB11000, Barbados

Sensors 2016, 16(11), 1901; https://doi.org/10.3390/s16111901 - 11 Nov 2016

Cited by 36 | Viewed by 6821

Abstract

A sensitive and reagentless electrochemical aptatoxisensor was developed on cobalt (II) salicylaldiimine metallodendrimer (SDD–Co(II)) doped with electro-synthesized silver nanoparticles (AgNPs) for microcystin-LR (L, l-leucine; R, l-arginine), or MC-LR, detection in the nanomolar range. The GCE|SDD–Co(II)|AgNPs aptatoxisensor was fabricated with 5’ thiolated [...] Read more.

A sensitive and reagentless electrochemical aptatoxisensor was developed on cobalt (II) salicylaldiimine metallodendrimer (SDD–Co(II)) doped with electro-synthesized silver nanoparticles (AgNPs) for microcystin-LR (L, l-leucine; R, l-arginine), or MC-LR, detection in the nanomolar range. The GCE|SDD–Co(II)|AgNPs aptatoxisensor was fabricated with 5’ thiolated aptamer through self-assembly on the modified surface of the glassy carbon electrode (GCE) and the electronic response was measured using cyclic voltammetry (CV). Specific binding of MC-LR with the aptamer on GCE|SDD–Co(II)|AgNPs aptatoxisensor caused the formation of a complex that resulted in steric hindrance and electrostatic repulsion culminating in variation of the corresponding peak current of the electrochemical probe. The aptatoxisensor showed a linear response for MC-LR between 0.1 and 1.1 µg·L⁻¹ and the calculated limit of detection (LOD) was 0.04 µg·L⁻¹. In the detection of MC-LR in water samples, the aptatoxisensor proved to be highly sensitive and stable, performed well in the presence of interfering analog and was comparable to the conventional analytical techniques. The results demonstrate that the constructed MC-LR aptatoxisensor is a suitable device for routine quantification of MC-LR in freshwater and environmental samples. Full article

(This article belongs to the Special Issue Aptasensors 2016)

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11 pages, 749 KiB

Open AccessArticle

Tunnel Magnetoresistance Sensors with Magnetostrictive Electrodes: Strain Sensors

by Ali Tavassolizadeh^1,*, Karsten Rott², Tobias Meier^3,†

, Eckhard Quandt¹, Hendrik Hölscher³, Günter Reiss² and Dirk Meyners^1,*

¹ Institute for Materials Science, Kiel University, Kaiserstrasse 2, 24143 Kiel, Germany

² Department of Physics, Bielefeld University, Universitätsstrasse 25, 33615 Bielefeld, Germany

³ Institute of Microstructure Technology, Karlsruhe Institute of Technology (KIT), Hermann-von-Helmholtz Platz 1, 76344 Eggenstein-Leopoldshafen, Germany

^† Current address: Department of Mechanical and Aerospace Engineering, The George Washington University, Washington, DC 20052, USA.

Sensors 2016, 16(11), 1902; https://doi.org/10.3390/s16111902 - 11 Nov 2016

Cited by 34 | Viewed by 9499

Abstract

Magnetostrictive tunnel magnetoresistance (TMR) sensors pose a bright perspective in micro- and nano-scale strain sensing technology. The behavior of TMR sensors under mechanical stress as well as their sensitivity to the applied stress depends on the magnetization configuration of magnetic tunnel junctions (MTJ)s [...] Read more.

Magnetostrictive tunnel magnetoresistance (TMR) sensors pose a bright perspective in micro- and nano-scale strain sensing technology. The behavior of TMR sensors under mechanical stress as well as their sensitivity to the applied stress depends on the magnetization configuration of magnetic tunnel junctions (MTJ)s with respect to the stress axis. Here, we propose a configuration resulting in an inverse effect on the tunnel resistance by tensile and compressive stresses. Numerical simulations, based on a modified Stoner–Wohlfarth (SW) model, are performed in order to understand the magnetization reversal of the sense layer and to find out the optimum bias magnetic field required for high strain sensitivity. At a bias field of −3.2 kA/m under a

0.2 \times 10^{- 3}

strain, gauge factors of 2294 and −311 are calculated under tensile and compressive stresses, respectively. Modeling results are investigated experimentally on a round junction with a diameter of

30 \pm 0.2

μ

m using a four-point bending apparatus. The measured field and strain loops exhibit nearly the same trends as the calculated ones. Also, the gauge factors are in the same range. The junction exhibits gauge factors of

2150 \pm 30

and −260 for tensile and compressive stresses, respectively, under a −3.2 kA/m bias magnetic field. The agreement of the experimental and modeling results approves the proposed configuration for high sensitivity and ability to detect both tensile and compressive stresses by a single TMR sensor. Full article

(This article belongs to the Special Issue Magnetoresistive Sensors under Extreme Conditions)

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18 pages, 2532 KiB

Open AccessArticle

Advanced Pedestrian Positioning System to Smartphones and Smartwatches

by Alejandro Correa^1,*

, Estefania Munoz Diaz², Dina Bousdar Ahmed²

, Antoni Morell¹

and Jose Lopez Vicario¹

¹ Telecommunications and Systems Engineering Department, Universitat Autònoma de Barcelona, Bellaterra 08193, Spain

² Institute of Communications and Navigation, German Aerospace Center, Oberpfaffenhofen 82234, Germany

Sensors 2016, 16(11), 1903; https://doi.org/10.3390/s16111903 - 11 Nov 2016

Cited by 27 | Viewed by 6912

Abstract

In recent years, there has been an increasing interest in the development of pedestrian navigation systems for satellite-denied scenarios. The popularization of smartphones and smartwatches is an interesting opportunity for reducing the infrastructure cost of the positioning systems. Nowadays, smartphones include inertial sensors [...] Read more.

In recent years, there has been an increasing interest in the development of pedestrian navigation systems for satellite-denied scenarios. The popularization of smartphones and smartwatches is an interesting opportunity for reducing the infrastructure cost of the positioning systems. Nowadays, smartphones include inertial sensors that can be used in pedestrian dead-reckoning (PDR) algorithms for the estimation of the user’s position. Both smartphones and smartwatches include WiFi capabilities allowing the computation of the received signal strength (RSS). We develop a new method for the combination of RSS measurements from two different receivers using a Gaussian mixture model. We also analyze the implication of using a WiFi network designed for communication purposes in an indoor positioning system when the designer cannot control the network configuration. In this work, we design a hybrid positioning system that combines inertial measurements, from low-cost inertial sensors embedded in a smartphone, with RSS measurements through an extended Kalman filter. The system has been validated in a real scenario, and results show that our system improves the positioning accuracy of the PDR system thanks to the use of two WiFi receivers. The designed system obtains an accuracy up to 1.4

m

in a scenario of 6000

m^{2}

. Full article

(This article belongs to the Special Issue Inertial Sensors and Systems 2016)

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21 pages, 10120 KiB

Open AccessArticle

DeepAnomaly: Combining Background Subtraction and Deep Learning for Detecting Obstacles and Anomalies in an Agricultural Field

by Peter Christiansen^1,*

, Lars N. Nielsen², Kim A. Steen³, Rasmus N. Jørgensen¹

and Henrik Karstoft¹

¹ Department of Engineering, Aarhus University, Aarhus 8200, Denmark

² Danske Commodities, Aarhus 8000, Denmark

³ AgroIntelli, Aarhus 8200, Denmark

Sensors 2016, 16(11), 1904; https://doi.org/10.3390/s16111904 - 11 Nov 2016

Cited by 134 | Viewed by 16762

Abstract

Convolutional neural network (CNN)-based systems are increasingly used in autonomous vehicles for detecting obstacles. CNN-based object detection and per-pixel classification (semantic segmentation) algorithms are trained for detecting and classifying a predefined set of object types. These algorithms have difficulties in detecting distant and [...] Read more.

Convolutional neural network (CNN)-based systems are increasingly used in autonomous vehicles for detecting obstacles. CNN-based object detection and per-pixel classification (semantic segmentation) algorithms are trained for detecting and classifying a predefined set of object types. These algorithms have difficulties in detecting distant and heavily occluded objects and are, by definition, not capable of detecting unknown object types or unusual scenarios. The visual characteristics of an agriculture field is homogeneous, and obstacles, like people, animals and other obstacles, occur rarely and are of distinct appearance compared to the field. This paper introduces DeepAnomaly, an algorithm combining deep learning and anomaly detection to exploit the homogenous characteristics of a field to perform anomaly detection. We demonstrate DeepAnomaly as a fast state-of-the-art detector for obstacles that are distant, heavily occluded and unknown. DeepAnomaly is compared to state-of-the-art obstacle detectors including “Faster R-CNN: Towards Real-Time Object Detection with Region Proposal Networks” (RCNN). In a human detector test case, we demonstrate that DeepAnomaly detects humans at longer ranges (45–90 m) than RCNN. RCNN has a similar performance at a short range (0–30 m). However, DeepAnomaly has much fewer model parameters and (182 ms/25 ms =) a 7.28-times faster processing time per image. Unlike most CNN-based methods, the high accuracy, the low computation time and the low memory footprint make it suitable for a real-time system running on a embedded GPU (Graphics Processing Unit). Full article

(This article belongs to the Special Issue Vision-Based Sensors in Field Robotics)

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10 pages, 4887 KiB

Open AccessArticle

Ultrasonic Al₂O₃ Ceramic Thermometry in High-Temperature Oxidation Environment

by Yanlong Wei^1,*, Yubin Gao¹, Zhaoqian Xiao², Gao Wang¹, Miao Tian¹ and Haijian Liang¹

¹ Science and Technology on Electronic Test & Measurement Laboratory, North University of China, Taiyuan 030051, China

² North Automatic Control Technique Research Institute, Taiyuan 030006, China

Sensors 2016, 16(11), 1905; https://doi.org/10.3390/s16111905 - 11 Nov 2016

Cited by 20 | Viewed by 6577

Abstract

In this study, an ultrasonic temperature measurement system was designed with Al₂O₃ high-temperature ceramic as an acoustic waveguide sensor and preliminarily tested in a high-temperature oxidation environment. The test results indicated that the system can indeed work stably in high-temperature [...] Read more.

In this study, an ultrasonic temperature measurement system was designed with Al₂O₃ high-temperature ceramic as an acoustic waveguide sensor and preliminarily tested in a high-temperature oxidation environment. The test results indicated that the system can indeed work stably in high-temperature environments. The relationship between the temperature and delay time of 26 °C–1600 °C ceramic materials was also determined in order to fully elucidate the high-temperature oxidation of the proposed waveguide sensor and to lay a foundation for the further application of this system in temperatures as high as 2000 °C. Full article

(This article belongs to the Section Physical Sensors)

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13 pages, 3377 KiB

Open AccessArticle

Effects of Non-Elevation-Focalized Linear Array Transducer on Ultrasound Plane-Wave Imaging

by Congzhi Wang, Yang Xiao, Jingjing Xia, Weibao Qiu^* and Hairong Zheng^*

Shenzhen Institutes of Advanced Technology, the Chinese Academy of Science, 1068 Xueyuan Avenue, Shenzhen University Town, Xili, Nanshan, Shenzhen 518055, China

Sensors 2016, 16(11), 1906; https://doi.org/10.3390/s16111906 - 12 Nov 2016

Cited by 2 | Viewed by 6770

Abstract

Plane-wave ultrasound imaging (PWUS) has become an important method of ultrasound imaging in recent years as its frame rate has exceeded 10,000 frames per second, allowing ultrasound to be used for two-dimensional shear wave detection and functional brain imaging. However, compared to the [...] Read more.

Plane-wave ultrasound imaging (PWUS) has become an important method of ultrasound imaging in recent years as its frame rate has exceeded 10,000 frames per second, allowing ultrasound to be used for two-dimensional shear wave detection and functional brain imaging. However, compared to the traditional focusing and scanning method, PWUS images always suffer from a degradation of lateral resolution and contrast. To improve the image quality of PWUS, many different beamforming algorithms have been proposed and verified. Yet the influence of transducer structure is rarely studied. For this paper, the influence of using an acoustic lens for PWUS was evaluated. Two linear array transducers were fabricated. One was not self-focalized in the elevation direction (non-elevation-focalized transducer, NEFT); the other one was a traditional elevation-focalized transducer (EFT). An initial simulation was conducted to show the influence of elevation focusing. Then the images obtained with NEFT on a standard ultrasound imaging phantom were compared with those obtained with EFT. It was demonstrated that, in a relatively deep region, the contrast of an NEFT image is better than that of an EFT image. These results indicate that a more sophisticated design of ultrasound transducer would further improve the image quality of PWUS. Full article

(This article belongs to the Special Issue Acoustic Sensing and Ultrasonic Drug Delivery)

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27 pages, 5619 KiB

Open AccessArticle

Efficient Time-Domain Imaging Processing for One-Stationary Bistatic Forward-Looking SAR Including Motion Errors

by Hongtu Xie^1,2,*, Shaoying Shi¹, Hui Xiao¹, Chao Xie¹, Feng Wang¹ and Qunle Fang¹

¹ Department of Air/Space-based Early Warning Equipment, Air Force Early Warning, Wuhan 430019, China

² College of Electronic Science and Engineering, National University of Defense Technology, Changsha 410073, China

Sensors 2016, 16(11), 1907; https://doi.org/10.3390/s16111907 - 12 Nov 2016

Cited by 16 | Viewed by 5178

Abstract

With the rapid development of the one-stationary bistatic forward-looking synthetic aperture radar (OS-BFSAR) technology, the huge amount of the remote sensing data presents challenges for real-time imaging processing. In this paper, an efficient time-domain algorithm (ETDA) considering the motion errors for the OS-BFSAR [...] Read more.

With the rapid development of the one-stationary bistatic forward-looking synthetic aperture radar (OS-BFSAR) technology, the huge amount of the remote sensing data presents challenges for real-time imaging processing. In this paper, an efficient time-domain algorithm (ETDA) considering the motion errors for the OS-BFSAR imaging processing, is presented. This method can not only precisely handle the large spatial variances, serious range-azimuth coupling and motion errors, but can also greatly improve the imaging efficiency compared with the direct time-domain algorithm (DTDA). Besides, it represents the subimages on polar grids in the ground plane instead of the slant-range plane, and derives the sampling requirements considering motion errors for the polar grids to offer a near-optimum tradeoff between the imaging precision and efficiency. First, OS-BFSAR imaging geometry is built, and the DTDA for the OS-BFSAR imaging is provided. Second, the polar grids of subimages are defined, and the subaperture imaging in the ETDA is derived. The sampling requirements for polar grids are derived from the point of view of the bandwidth. Finally, the implementation and computational load of the proposed ETDA are analyzed. Experimental results based on simulated and measured data validate that the proposed ETDA outperforms the DTDA in terms of the efficiency improvement. Full article

(This article belongs to the Special Issue Synthetic Aperture Radars: Models, Algorithms, Techniques and Tools for Data Exploitation)

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16 pages, 498 KiB

Open AccessArticle

Secure Multiuser Communications in Wireless Sensor Networks with TAS and Cooperative Jamming

by Maoqiang Yang^1,†, Bangning Zhang^1,†

, Yuzhen Huang^1,†, Nan Yang^2,†, Daoxing Guo^1,*,†

and Bin Gao^1,†

¹ College of Communications Engineering, PLA University of Science and Technology, No. 2 Biaoying, Qinhuai District, Nanjing 210007, China

² Research School of Engineering, Australian National University, Canberra, ACT 2601, Australia

^† These authors contributed equally to this work.

Sensors 2016, 16(11), 1908; https://doi.org/10.3390/s16111908 - 12 Nov 2016

Cited by 16 | Viewed by 6120

Abstract

In this paper, we investigate the secure transmission in wireless sensor networks (WSNs) consisting of one multiple-antenna base station (BS), multiple single-antenna legitimate users, one single-antenna eavesdropper and one multiple-antenna cooperative jammer. In an effort to reduce the scheduling complexity and extend the [...] Read more.

In this paper, we investigate the secure transmission in wireless sensor networks (WSNs) consisting of one multiple-antenna base station (BS), multiple single-antenna legitimate users, one single-antenna eavesdropper and one multiple-antenna cooperative jammer. In an effort to reduce the scheduling complexity and extend the battery lifetime of the sensor nodes, the switch-and-stay combining (SSC) scheduling scheme is exploited over the sensor nodes. Meanwhile, transmit antenna selection (TAS) is employed at the BS and cooperative jamming (CJ) is adopted at the jammer node, aiming at achieving a satisfactory secrecy performance. Moreover, depending on whether the jammer node has the global channel state information (CSI) of both the legitimate channel and the eavesdropper’s channel, it explores a zero-forcing beamforming (ZFB) scheme or a null-space artificial noise (NAN) scheme to confound the eavesdropper while avoiding the interference to the legitimate user. Building on this, we propose two novel hybrid secure transmission schemes, termed TAS-SSC-ZFB and TAS-SSC-NAN, for WSNs. We then derive the exact closed-form expressions for the secrecy outage probability and the effective secrecy throughput of both schemes to characterize the secrecy performance. Using these closed-form expressions, we further determine the optimal switching threshold and obtain the optimal power allocation factor between the BS and jammer node for both schemes to minimize the secrecy outage probability, while the optimal secrecy rate is decided to maximize the effective secrecy throughput for both schemes. Numerical results are provided to verify the theoretical analysis and illustrate the impact of key system parameters on the secrecy performance. Full article

(This article belongs to the Special Issue Trusted and Secure Wireless Sensor Network Designs and Deployments)

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13 pages, 2729 KiB

Open AccessArticle

Optical Aptamer Probes of Fluorescent Imaging to Rapid Monitoring of Circulating Tumor Cell

by Ji Yeon Hwang^1,2,†, Sang Tae Kim^3,†, Ho-Seong Han³, Kyunggon Kim⁴ and Jin Soo Han^2,*

¹ Preclinical Research Center, Biomedical Research Institute, Seoul National University Bundang Hospital, 82, Gumi-ro 173beon-gil, Bundang-gu, Seongnam-si, Gyeonggi-do 13620, Korea

² The Institute for the 3Rs, College of Veterinary Medicine, Konkuk University, 120 Neungdong-ro, Gwangjin-gu, Seoul 05029, Korea

³ Department of Surgery, Seoul National University Bundang Hospital, 82, Gumi-ro 173beon-gil, Bundang-gu, Seongnam-si, Gyeonggi-do 13620, Korea

⁴ Asan Institute for Life Sciences, Asan Medical Center, Seoul, Department of Medicine, University of Ulsan College of Medicine, 43 gil Olympic-ro, Pungnap dong, Songpa gu, Seoul 138-736, Korea

^† These authors contributed equally to this work.

Sensors 2016, 16(11), 1909; https://doi.org/10.3390/s16111909 - 23 Nov 2016

Cited by 21 | Viewed by 7139

Abstract

Fluorescence detecting of exogenous EpCAM (epithelial cell adhesion molecule) or muc1 (mucin1) expression correlated to cancer metastasis using nanoparticles provides pivotal information on CTC (circulating tumor cell) occurrence in a noninvasive tool. In this study, we study a new skill to detect extracellular [...] Read more.

Fluorescence detecting of exogenous EpCAM (epithelial cell adhesion molecule) or muc1 (mucin1) expression correlated to cancer metastasis using nanoparticles provides pivotal information on CTC (circulating tumor cell) occurrence in a noninvasive tool. In this study, we study a new skill to detect extracellular EpCAM/muc1 using quantum dot-based aptamer beacon (QD-EpCAM/muc1 ALB (aptamer linker beacon). The QD-EpCAM/muc1 ALB was designed using QDs (quantum dots) and probe. The EpCAM/muc1-targeting aptamer contains a Ep-CAM/muc1 binding sequence and BHQ1 (black hole quencher 1) or BHQ2 (black hole quencher2). In the absence of target EpCAM/muc1, the QD-EpCAM/muc1 ALB forms a partial duplex loop-like aptamer beacon and remained in quenched state because the BHQ1/2 quenches the fluorescence signal-on of the QD-EpCAM/muc1 ALB. The binding of EpCAM/muc1 of CTC to the EpCAM/muc1 binding aptamer sequence of the EpCAM/muc1-targeting oligonucleotide triggered the dissociation of the BHQ1/2 quencher and subsequent signal-on of a green/red fluorescence signal. Furthermore, acute inflammation was stimulated by trigger such as caerulein in vivo, which resulted in increased fluorescent signal of the cy5.5-EpCAM/muc1 ALB during cancer metastasis due to exogenous expression of EpCAM/muc1 in Panc02-implanted mouse model. Full article

(This article belongs to the Special Issue Nanobiosensing for Sensors)

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23 pages, 877 KiB

Open AccessArticle

Interference-Robust Transmission in Wireless Sensor Networks

by Jin-Seok Han

and Yong-Hwan Lee^*

Department of Electrical and Computer Engineering and INMC, Seoul National University, Seoul 151-742, Korea

Sensors 2016, 16(11), 1910; https://doi.org/10.3390/s16111910 - 14 Nov 2016

Cited by 7 | Viewed by 4796

Abstract

Low-power wireless sensor networks (WSNs) operating in unlicensed spectrum bands may seriously suffer from interference from other coexisting radio systems, such as IEEE 802.11 wireless local area networks. In this paper, we consider the improvement of the transmission performance of low-power WSNs by [...] Read more.

Low-power wireless sensor networks (WSNs) operating in unlicensed spectrum bands may seriously suffer from interference from other coexisting radio systems, such as IEEE 802.11 wireless local area networks. In this paper, we consider the improvement of the transmission performance of low-power WSNs by adjusting the transmission rate and the payload size in response to the change of co-channel interference. We estimate the probability of transmission failure and the data throughput and then determine the payload size to maximize the throughput performance. We investigate that the transmission time maximizing the normalized throughput is not much affected by the transmission rate, but rather by the interference condition. We adjust the transmission rate and the transmission time in response to the change of the channel and interference condition, respectively. Finally, we verify the performance of the proposed scheme by computer simulation. The simulation results show that the proposed scheme significantly improves data throughput compared with conventional schemes while preserving energy efficiency even in the presence of interference. Full article

(This article belongs to the Section Sensor Networks)

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8 pages, 2794 KiB

Open AccessArticle

A Microfluidic DNA Sensor Based on Three-Dimensional (3D) Hierarchical MoS₂/Carbon Nanotube Nanocomposites

by Dahou Yang, Mahnoush Tayebi, Yinxi Huang, Hui Ying Yang and Ye Ai^*

Pillar of Engineering Product Development, Singapore University of Technology and Design, Singapore 487372, Singapore

Sensors 2016, 16(11), 1911; https://doi.org/10.3390/s16111911 - 14 Nov 2016

Cited by 21 | Viewed by 6837

Abstract

In this work, we present a novel microfluidic biosensor for sensitive fluorescence detection of DNA based on 3D architectural MoS₂/multi-walled carbon nanotube (MWCNT) nanocomposites. The proposed platform exhibits a high sensitivity, selectivity, and stability with a visible manner and operation simplicity. [...] Read more.

In this work, we present a novel microfluidic biosensor for sensitive fluorescence detection of DNA based on 3D architectural MoS₂/multi-walled carbon nanotube (MWCNT) nanocomposites. The proposed platform exhibits a high sensitivity, selectivity, and stability with a visible manner and operation simplicity. The excellent fluorescence quenching stability of a MoS₂/MWCNT aqueous solution coupled with microfluidics will greatly simplify experimental steps and reduce time for large-scale DNA detection. Full article

(This article belongs to the Special Issue Biosensors and Molecular Imprinting)

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22 pages, 13173 KiB

Open AccessArticle

Laboratory Performance of Five Selected Soil Moisture Sensors Applying Factory and Own Calibration Equations for Two Soil Media of Different Bulk Density and Salinity Levels

by Svatopluk Matula^1,*, Kamila Báťková¹

and Wossenu Lemma Legese^1,2

¹ Department of Water Resources, Faculty of Agrobiology, Food and Natural Resources, Czech University of Life Sciences, Kamýcká 129, 165 21 Praha 6—Suchdol, Czech Republic

² Department of Water Supply and Sanitary, School of Environment and Energy Resource Engineering, Addis Ababa Science and Technology University, P.O. Box 16417, Addis Ababa, Ethiopia

Sensors 2016, 16(11), 1912; https://doi.org/10.3390/s16111912 - 15 Nov 2016

Cited by 59 | Viewed by 12435

Abstract

Non-destructive soil water content determination is a fundamental component for many agricultural and environmental applications. The accuracy and costs of the sensors define the measurement scheme and the ability to fit the natural heterogeneous conditions. The aim of this study was to evaluate [...] Read more.

Non-destructive soil water content determination is a fundamental component for many agricultural and environmental applications. The accuracy and costs of the sensors define the measurement scheme and the ability to fit the natural heterogeneous conditions. The aim of this study was to evaluate five commercially available and relatively cheap sensors usually grouped with impedance and FDR sensors. ThetaProbe ML2x (impedance) and ECH₂O EC-10, ECH₂O EC-20, ECH₂O EC-5, and ECH₂O TE (all FDR) were tested on silica sand and loess of defined characteristics under controlled laboratory conditions. The calibrations were carried out in nine consecutive soil water contents from dry to saturated conditions (pure water and saline water). The gravimetric method was used as a reference method for the statistical evaluation (ANOVA with significance level 0.05). Generally, the results showed that our own calibrations led to more accurate soil moisture estimates. Variance component analysis arranged the factors contributing to the total variation as follows: calibration (contributed 42%), sensor type (contributed 29%), material (contributed 18%), and dry bulk density (contributed 11%). All the tested sensors performed very well within the whole range of water content, especially the sensors ECH₂O EC-5 and ECH₂O TE, which also performed surprisingly well in saline conditions. Full article

(This article belongs to the Collection Sensors in Agriculture and Forestry)

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19 pages, 5144 KiB

Open AccessArticle

Development of Cloud-Based UAV Monitoring and Management System

by Mason Itkin¹, Mihui Kim²

and Younghee Park^1,*

¹ Computer Engineering Department, San Jose State University, One Washington Square, San Jose, CA 95192, USA

² Department of Computer Science & Engineering, Computer System Institute, Hankyong National University, 327 Jungang-ro, Anseong-si, Gyeonggi-do 456-749, Korea

Sensors 2016, 16(11), 1913; https://doi.org/10.3390/s16111913 - 15 Nov 2016

Cited by 58 | Viewed by 9582

Abstract

Unmanned aerial vehicles (UAVs) are an emerging technology with the potential to revolutionize commercial industries and the public domain outside of the military. UAVs would be able to speed up rescue and recovery operations from natural disasters and can be used for autonomous [...] Read more.

Unmanned aerial vehicles (UAVs) are an emerging technology with the potential to revolutionize commercial industries and the public domain outside of the military. UAVs would be able to speed up rescue and recovery operations from natural disasters and can be used for autonomous delivery systems (e.g., Amazon Prime Air). An increase in the number of active UAV systems in dense urban areas is attributed to an influx of UAV hobbyists and commercial multi-UAV systems. As airspace for UAV flight becomes more limited, it is important to monitor and manage many UAV systems using modern collision avoidance techniques. In this paper, we propose a cloud-based web application that provides real-time flight monitoring and management for UAVs. For each connected UAV, detailed UAV sensor readings from the accelerometer, GPS sensor, ultrasonic sensor and visual position cameras are provided along with status reports from the smaller internal components of UAVs (i.e., motor and battery). The dynamic map overlay visualizes active flight paths and current UAV locations, allowing the user to monitor all aircrafts easily. Our system detects and prevents potential collisions by automatically adjusting UAV flight paths and then alerting users to the change. We develop our proposed system and demonstrate its feasibility and performances through simulation. Full article

(This article belongs to the Special Issue UAV-Based Remote Sensing)

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17 pages, 3326 KiB

Open AccessArticle

A New Multi-Sensor Fusion Scheme to Improve the Accuracy of Knee Flexion Kinematics for Functional Rehabilitation Movements

by Halim Tannous^1,*, Dan Istrate¹

, Aziz Benlarbi-Delai², Julien Sarrazin², Didier Gamet¹, Marie Christine Ho Ba Tho¹ and Tien Tuan Dao¹

¹ Sorbonne University, Université de Technologie de Compiègne, CNRS, UMR 7338 Biomechanics and Bioengineering, 60200 Compiègne, France

² Sorbonne University, Université Pierre et Marie Curie, L2E, Place Jussieu, 75252 Paris, France

Sensors 2016, 16(11), 1914; https://doi.org/10.3390/s16111914 - 15 Nov 2016

Cited by 48 | Viewed by 8001

Abstract

Exergames have been proposed as a potential tool to improve the current practice of musculoskeletal rehabilitation. Inertial or optical motion capture sensors are commonly used to track the subject’s movements. However, the use of these motion capture tools suffers from the lack of [...] Read more.

Exergames have been proposed as a potential tool to improve the current practice of musculoskeletal rehabilitation. Inertial or optical motion capture sensors are commonly used to track the subject’s movements. However, the use of these motion capture tools suffers from the lack of accuracy in estimating joint angles, which could lead to wrong data interpretation. In this study, we proposed a real time quaternion-based fusion scheme, based on the extended Kalman filter, between inertial and visual motion capture sensors, to improve the estimation accuracy of joint angles. The fusion outcome was compared to angles measured using a goniometer. The fusion output shows a better estimation, when compared to inertial measurement units and Kinect outputs. We noted a smaller error (3.96°) compared to the one obtained using inertial sensors (5.04°). The proposed multi-sensor fusion system is therefore accurate enough to be applied, in future works, to our serious game for musculoskeletal rehabilitation. Full article

(This article belongs to the Section Sensor Networks)

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25 pages, 51264 KiB

Open AccessArticle

Image Based Mango Fruit Detection, Localisation and Yield Estimation Using Multiple View Geometry

by Madeleine Stein¹, Suchet Bargoti² and James Underwood^2,*

¹ Division of Automatic Control Department of Electrical Engineering, Linköping University, Linköping SE-581 83, Sweden

² The Australian Centre for Field Robotics (ACFR), Department of Aerospace, Mechanical and Mechatronic Engineering (AMME),The University of Sydney, Sydney, NSW 2006, Australia

Sensors 2016, 16(11), 1915; https://doi.org/10.3390/s16111915 - 15 Nov 2016

Cited by 269 | Viewed by 23058

Abstract

This paper presents a novel multi-sensor framework to efficiently identify, track, localise and map every piece of fruit in a commercial mango orchard. A multiple viewpoint approach is used to solve the problem of occlusion, thus avoiding the need for labour-intensive field calibration [...] Read more.

This paper presents a novel multi-sensor framework to efficiently identify, track, localise and map every piece of fruit in a commercial mango orchard. A multiple viewpoint approach is used to solve the problem of occlusion, thus avoiding the need for labour-intensive field calibration to estimate actual yield. Fruit are detected in images using a state-of-the-art faster R-CNN detector, and pair-wise correspondences are established between images using trajectory data provided by a navigation system. A novel LiDAR component automatically generates image masks for each canopy, allowing each fruit to be associated with the corresponding tree. The tracked fruit are triangulated to locate them in 3D, enabling a number of spatial statistics per tree, row or orchard block. A total of 522 trees and 71,609 mangoes were scanned on a Calypso mango orchard near Bundaberg, Queensland, Australia, with 16 trees counted by hand for validation, both on the tree and after harvest. The results show that single, dual and multi-view methods can all provide precise yield estimates, but only the proposed multi-view approach can do so without calibration, with an error rate of only 1.36% for individual trees. Full article

(This article belongs to the Special Issue Vision-Based Sensors in Field Robotics)

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16 pages, 4041 KiB

Open AccessArticle

Optimized Detection of Plasmodium falciparum Topoisomerase I Enzyme Activity in a Complex Biological Sample by the Use of Molecular Beacons

by Asger Givskov¹, Emil L. Kristoffersen¹, Kamilla Vandsø¹, Yi-Ping Ho²

, Magnus Stougaard³ and Birgitta R. Knudsen^1,*

¹ Department of Molecular Biology and Genetics, Aarhus University, 8000 Aarhus C, Denmark

² Division of Biomedical Engineering, Department of Electronic Engineering, The Chinese University of Hong Kong, Shatin, New Territories 999077, Hong Kong, China

³ Department of Pathology, Aarhus University Hospital, 8000 Aarhus C, Denmark

Sensors 2016, 16(11), 1916; https://doi.org/10.3390/s16111916 - 15 Nov 2016

Cited by 8 | Viewed by 6344

Abstract

The so-called Rolling Circle Amplification allows for amplification of circular DNA structures in a manner that can be detected in real-time using nucleotide-based molecular beacons that unfold upon recognition of the DNA product, which is being produced during the amplification process. The unfolding [...] Read more.

The so-called Rolling Circle Amplification allows for amplification of circular DNA structures in a manner that can be detected in real-time using nucleotide-based molecular beacons that unfold upon recognition of the DNA product, which is being produced during the amplification process. The unfolding of the molecular beacons results in a fluorescence increase as the Rolling Circle Amplification proceeds. This can be measured in a fluorometer. In the current study, we have investigated the possibility of using two different molecular beacons to detect two distinct Rolling Circle Amplification reactions proceeding simultaneously and in the same reaction tube by measurement of fluorescence over time. We demonstrate the application of this fluorometric readout method, for automated and specific detection of the activity of the type IB topoisomerase from the malaria parasite Plasmodium falciparum in the presence of human cell extract containing the related topoisomerase I from humans. The obtained results point towards a future use of the presented assay setup for malaria diagnostics or drug screening purposes. In longer terms the method may be applied more broadly for real-time sensing of various Rolling Circle Amplification reactions. Full article

(This article belongs to the Special Issue Point-of-Care Biosensors)

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13 pages, 4572 KiB

Open AccessArticle

Polypyrrole Nanotubes and Their Carbonized Analogs: Synthesis, Characterization, Gas Sensing Properties

by Jitka Kopecká¹, Miroslav Mrlík², Robert Olejník², Dušan Kopecký^1,*, Martin Vrňata¹, Jan Prokeš³, Patrycja Bober⁴

, Zuzana Morávková⁴, Miroslava Trchová⁴ and Jaroslav Stejskal⁴

¹ Department of Physics and Measurements, University of Chemistry and Technology Prague, Prague 6 CZ–166 28, Czech Republic

² Centre of Polymer Systems, University Institute, Tomas Bata University in Zlin, Zlin, CZ–760 01, Czech Republic

³ Faculty of Mathematics and Physics, Charles University in Prague, Prague 8, CZ–180 00, Czech Republic

⁴ Institute of Macromolecular Chemistry, Academy of Sciences of the Czech Republic, Prague 6, CZ–162 06, Czech Republic

Sensors 2016, 16(11), 1917; https://doi.org/10.3390/s16111917 - 15 Nov 2016

Cited by 52 | Viewed by 7412

Abstract

Polypyrrole (PPy) in globular form and as nanotubes were prepared by the oxidation of pyrrole with iron(III) chloride in the absence and presence of methyl orange, respectively. They were subsequently converted to nitrogen-containing carbons at 650 °C in an inert atmosphere. The course [...] Read more.

Polypyrrole (PPy) in globular form and as nanotubes were prepared by the oxidation of pyrrole with iron(III) chloride in the absence and presence of methyl orange, respectively. They were subsequently converted to nitrogen-containing carbons at 650 °C in an inert atmosphere. The course of carbonization was followed by thermogravimetric analysis and the accompanying changes in molecular structure by Fourier Transform Infrared and Raman spectroscopies. Both the original and carbonized materials have been tested in sensing of polar and non-polar organic vapors. The resistivity of sensing element using globular PPy was too high and only nanotubular PPy could be used. The sensitivity of the PPy nanotubes to ethanol vapors was nearly on the same level as that of their carbonized analogs (i.e., ~18% and 24%, respectively). Surprisingly, there was a high sensitivity of PPy nanotubes to the n-heptane vapors (~110%), while that of their carbonized analog remained at ~20%. The recovery process was significantly faster for carbonized PPy nanotubes (in order of seconds) compared with 10 s of seconds for original nanotubes, respectively, due to higher specific surface area after carbonization. Full article

(This article belongs to the Section Chemical Sensors)

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16 pages, 2721 KiB

Open AccessArticle

Investigating the Utility of Oblique Tree-Based Ensembles for the Classification of Hyperspectral Data

by Nitesh Poona^1,*

, Adriaan Van Niekerk^1,2

and Riyad Ismail¹

¹ Department of Geography and Environmental Studies, Stellenbosch University, Stellenbosch 7602, South Africa

² School of Plant Biology, University of Western Australia, 35 Stirling Hwy, Crawley, Perth, WA 6009, Australia

Sensors 2016, 16(11), 1918; https://doi.org/10.3390/s16111918 - 15 Nov 2016

Cited by 17 | Viewed by 4918

Abstract

Ensemble classifiers are being widely used for the classification of spectroscopic data. In this regard, the random forest (RF) ensemble has been successfully applied in an array of applications, and has proven to be robust in handling high dimensional data. More recently, several [...] Read more.

Ensemble classifiers are being widely used for the classification of spectroscopic data. In this regard, the random forest (RF) ensemble has been successfully applied in an array of applications, and has proven to be robust in handling high dimensional data. More recently, several variants of the traditional RF algorithm including rotation forest (rotF) and oblique random forest (oRF) have been applied to classifying high dimensional data. In this study we compare the traditional RF, rotF, and oRF (using three different splitting rules, i.e., ridge regression, partial least squares, and support vector machine) for the classification of healthy and infected Pinus radiata seedlings using high dimensional spectroscopic data. We further test the robustness of these five ensemble classifiers to reduced spectral resolution by spectral resampling (binning) of the original spectral bands. The results showed that the three oblique random forest ensembles outperformed both the traditional RF and rotF ensembles. Additionally, the rotF ensemble proved to be the least robust of the five ensembles tested. Spectral resampling of the original bands provided mixed results. Nevertheless, the results demonstrate that using spectral resampled bands is a promising approach to classifying asymptomatic stress in Pinus radiata seedlings. Full article

(This article belongs to the Section Remote Sensors)

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11 pages, 1672 KiB

Open AccessArticle

Wastewater Biosolid Composting Optimization Based on UV-VNIR Spectroscopy Monitoring

by Beatriz Temporal-Lara, Ignacio Melendez-Pastor

, Ignacio Gómez^* and Jose Navarro-Pedreño

Department of Agrochemistry and Environment, University Miguel Hernández of Elche (UMH), Avenida Universidad s/n Edificio Alcudia, 03202 Elche, Spain

Sensors 2016, 16(11), 1919; https://doi.org/10.3390/s16111919 - 15 Nov 2016

Cited by 11 | Viewed by 4631

Abstract

Conventional wastewater treatment generates large amounts of organic matter–rich sludge that requires adequate treatment to avoid public health and environmental problems. The mixture of wastewater sludge and some bulking agents produces a biosolid to be composted at adequate composting facilities. The composting process [...] Read more.

Conventional wastewater treatment generates large amounts of organic matter–rich sludge that requires adequate treatment to avoid public health and environmental problems. The mixture of wastewater sludge and some bulking agents produces a biosolid to be composted at adequate composting facilities. The composting process is chemically and microbiologically complex and requires an adequate aeration of the biosolid (e.g., with a turner machine) for proper maturation of the compost. Adequate (near) real-time monitoring of the compost maturity process is highly difficult and the operation of composting facilities is not as automatized as other industrial processes. Spectroscopic analysis of compost samples has been successfully employed for compost maturity assessment but the preparation of the solid compost samples is difficult and time-consuming. This manuscript presents a methodology based on a combination of a less time-consuming compost sample preparation and ultraviolet, visible and short-wave near-infrared spectroscopy. Spectroscopic measurements were performed with liquid compost extract instead of solid compost samples. Partial least square (PLS) models were developed to quantify chemical fractions commonly employed for compost maturity assessment. Effective regression models were obtained for total organic matter (residual predictive deviation—RPD = 2.68), humification ratio (RPD = 2.23), total exchangeable carbon (RPD = 2.07) and total organic carbon (RPD = 1.66) with a modular and cost-effective visible and near infrared (VNIR) spectroradiometer. This combination of a less time-consuming compost sample preparation with a versatile sensor system provides an easy-to-implement, efficient and cost-effective protocol for compost maturity assessment and near-real-time monitoring. Full article

(This article belongs to the Section Chemical Sensors)

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12 pages, 4103 KiB

Open AccessArticle

MEMS Inertial Sensors-Based Multi-Loop Control Enhanced by Disturbance Observation and Compensation for Fast Steering Mirror System

by Chao Deng^1,2,3, Yao Mao^1,2,*

and Ge Ren^1,2

¹ Institute of Optics and Electronics, Chinese Academy of Science, Chengdu 610209, China

² Key Laboratory of Optical Engineering, Chinese Academy of Sciences, Chengdu 610209, China

³ University of Chinese Academy of Science, Beijing 100039, China

Sensors 2016, 16(11), 1920; https://doi.org/10.3390/s16111920 - 15 Nov 2016

Cited by 44 | Viewed by 10536

Abstract

In this paper, an approach to improve the disturbance suppression performance of a fast steering mirror (FSM) tracking control system based on a charge-coupled device (CCD) and micro-electro-mechanical system (MEMS) inertial sensors is proposed. The disturbance observation and compensation (DOC) control method is [...] Read more.

In this paper, an approach to improve the disturbance suppression performance of a fast steering mirror (FSM) tracking control system based on a charge-coupled device (CCD) and micro-electro-mechanical system (MEMS) inertial sensors is proposed. The disturbance observation and compensation (DOC) control method is recommended to enhance the classical multi-loop feedback control (MFC) for line-of-sight (LOS) stabilization in the FSM system. MEMS accelerometers and gyroscopes have been used in the FSM system tentatively to implement MFC instead of fiber-optic gyroscopes (FOG) because of its smaller, lighter, cheaper features and gradually improved performance. However, the stabilization performance of FSM is still suffering a large number of mechanical resonances and time delay induced by a low CCD sampling rate, which causes insufficient error attenuation when suffering uncertain disturbances. Thus, in order to make further improvements on the stabilization performance, a cascaded MFC enhanced by DOC method is proposed. The sensitivity of this method shows the significant improvement of the conventional MFC system. Simultaneously, the analysis of stabilization accuracy is also presented. A series of comparative experimental results demonstrate the disturbance suppression performance of the FSM control system based on the MEMS inertial sensors can be effectively improved by the proposed approach. Full article

(This article belongs to the Collection Modeling, Testing and Reliability Issues in MEMS Engineering)

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17 pages, 4992 KiB

Open AccessArticle

Cellular Automata-Based Application for Driver Assistance in Indoor Parking Areas

by Cándido Caballero-Gil^*

, Pino Caballero-Gil

and Jezabel Molina-Gil

Department of Computer Engineering and Systems, University of La Laguna, La Laguna 38271, Tenerife, Spain

Sensors 2016, 16(11), 1921; https://doi.org/10.3390/s16111921 - 15 Nov 2016

Cited by 13 | Viewed by 6618

Abstract

This work proposes an adaptive recommendation mechanism for smart parking that takes advantage of the popularity of smartphones and the rise of the Internet of Things. The proposal includes a centralized system to forecast available indoor parking spaces, and a low-cost mobile application [...] Read more.

This work proposes an adaptive recommendation mechanism for smart parking that takes advantage of the popularity of smartphones and the rise of the Internet of Things. The proposal includes a centralized system to forecast available indoor parking spaces, and a low-cost mobile application to obtain data of actual and predicted parking occupancy. The described scheme uses data from both sources bidirectionally so that the centralized forecast system is fed with data obtained with the distributed system based on smartphones, and vice versa. The mobile application uses different wireless technologies to provide the forecast system with actual parking data and receive from the system useful recommendations about where to park. Thus, the proposal can be used by any driver to easily find available parking spaces in indoor facilities. The client software developed for smartphones is a lightweight Android application that supplies precise indoor positioning systems based on Quick Response codes or Near Field Communication tags, and semi-precise indoor positioning systems based on Bluetooth Low Energy beacons. The performance of the proposed approach has been evaluated by conducting computer simulations and real experimentation with a preliminary implementation. The results have shown the strengths of the proposal in the reduction of the time and energy costs to find available parking spaces. Full article

(This article belongs to the Special Issue Selected Papers from UCAmI, IWAAL and AmIHEALTH 2015)

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17 pages, 3918 KiB

Open AccessArticle

Detection of Multiple Stationary Humans Using UWB MIMO Radar

by Fulai Liang^†, Fugui Qi^†, Qiang An, Hao Lv, Fuming Chen, Zhao Li and Jianqi Wang^*

¹ School of Biomedical Engineering, Fourth Military Medical University, Xi’an 710032, China

^† These authors contributed equally to this work.

Sensors 2016, 16(11), 1922; https://doi.org/10.3390/s16111922 - 16 Nov 2016

Cited by 40 | Viewed by 8601

Abstract

Remarkable progress has been achieved in the detection of single stationary human. However, restricted by the mutual interference of multiple humans (e.g., strong sidelobes of the torsos and the shadow effect), detection and localization of the multiple stationary humans remains a huge challenge. [...] Read more.

Remarkable progress has been achieved in the detection of single stationary human. However, restricted by the mutual interference of multiple humans (e.g., strong sidelobes of the torsos and the shadow effect), detection and localization of the multiple stationary humans remains a huge challenge. In this paper, ultra-wideband (UWB) multiple-input and multiple-output (MIMO) radar is exploited to improve the detection performance of multiple stationary humans for its multiple sight angles and high-resolution two-dimensional imaging capacity. A signal model of the vital sign considering both bi-static angles and attitude angle of the human body is firstly developed, and then a novel detection method is proposed to detect and localize multiple stationary humans. In this method, preprocessing is firstly implemented to improve the signal-to-noise ratio (SNR) of the vital signs, and then a vital-sign-enhanced imaging algorithm is presented to suppress the environmental clutters and mutual affection of multiple humans. Finally, an automatic detection algorithm including constant false alarm rate (CFAR), morphological filtering and clustering is implemented to improve the detection performance of weak human targets affected by heavy clutters and shadow effect. The simulation and experimental results show that the proposed method can get a high-quality image of multiple humans and we can use it to discriminate and localize multiple adjacent human targets behind brick walls. Full article

(This article belongs to the Special Issue Advances in Applied Remote Sensing and Decision Making: Transforming Hazard Assessment and Environmental Management)

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23 pages, 25637 KiB

Open AccessArticle

3D Scene Reconstruction Using Omnidirectional Vision and LiDAR: A Hybrid Approach

by Michiel Vlaminck^1,*

, Hiep Luong¹, Werner Goeman² and Wilfried Philips¹

¹ Department of Telecommunications and Information Processing, Ghent University, Sint-Pietersnieuwstraat 41, iMinds, Ghent 9000, Belgium

² Sweco/Grontmij, Ghent 9000, Belgium

Sensors 2016, 16(11), 1923; https://doi.org/10.3390/s16111923 - 16 Nov 2016

Cited by 18 | Viewed by 10233

Abstract

In this paper, we propose a novel approach to obtain accurate 3D reconstructions of large-scale environments by means of a mobile acquisition platform. The system incorporates a Velodyne LiDAR scanner, as well as a Point Grey Ladybug panoramic camera system. It was designed [...] Read more.

In this paper, we propose a novel approach to obtain accurate 3D reconstructions of large-scale environments by means of a mobile acquisition platform. The system incorporates a Velodyne LiDAR scanner, as well as a Point Grey Ladybug panoramic camera system. It was designed with genericity in mind, and hence, it does not make any assumption about the scene or about the sensor set-up. The main novelty of this work is that the proposed LiDAR mapping approach deals explicitly with the inhomogeneous density of point clouds produced by LiDAR scanners. To this end, we keep track of a global 3D map of the environment, which is continuously improved and refined by means of a surface reconstruction technique. Moreover, we perform surface analysis on consecutive generated point clouds in order to assure a perfect alignment with the global 3D map. In order to cope with drift, the system incorporates loop closure by determining the pose error and propagating it back in the pose graph. Our algorithm was exhaustively tested on data captured at a conference building, a university campus and an industrial site of a chemical company. Experiments demonstrate that it is capable of generating highly accurate 3D maps in very challenging environments. We can state that the average distance of corresponding point pairs between the ground truth and estimated point cloud approximates one centimeter for an area covering approximately 4000 m

^{2}

. To prove the genericity of the system, it was tested on the well-known Kitti vision benchmark. The results show that our approach competes with state of the art methods without making any additional assumptions. Full article

(This article belongs to the Special Issue Vision-Based Sensors in Field Robotics)

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19 pages, 2664 KiB

Open AccessArticle

Geometric Distribution-Based Readers Scheduling Optimization Algorithm Using Artificial Immune System

by Litian Duan¹

, Zizhong John Wang^1,2 and Fu Duan^3,*

¹ College of Information Engineering, Taiyuan University of Technology, Taiyuan 030024, China

² Department of Mathematics and Computer Science, Virginia Wesleyan College, Norfolk, VA 23502, USA

³ College of Computer Science and Technology, Taiyuan University of Technology, Taiyuan 030024, China

Sensors 2016, 16(11), 1924; https://doi.org/10.3390/s16111924 - 16 Nov 2016

Cited by 2 | Viewed by 4108

Abstract

In the multiple-reader environment (MRE) of radio frequency identification (RFID) system, multiple readers are often scheduled to interrogate the randomized tags via operating at different time slots or frequency channels to decrease the signal interferences. Based on this, a Geometric Distribution-based Multiple-reader Scheduling [...] Read more.

In the multiple-reader environment (MRE) of radio frequency identification (RFID) system, multiple readers are often scheduled to interrogate the randomized tags via operating at different time slots or frequency channels to decrease the signal interferences. Based on this, a Geometric Distribution-based Multiple-reader Scheduling Optimization Algorithm using Artificial Immune System (GD-MRSOA-AIS) is proposed to fairly and optimally schedule the readers operating from the viewpoint of resource allocations. GD-MRSOA-AIS is composed of two parts, where a geometric distribution function combined with the fairness consideration is first introduced to generate the feasible scheduling schemes for reader operation. After that, artificial immune system (including immune clone, immune mutation and immune suppression) quickly optimize these feasible ones as the optimal scheduling scheme to ensure that readers are fairly operating with larger effective interrogation range and lower interferences. Compared with the state-of-the-art algorithm, the simulation results indicate that GD-MRSOA-AIS could efficiently schedules the multiple readers operating with a fairer resource allocation scheme, performing in larger effective interrogation range. Full article

(This article belongs to the Special Issue Advanced Algorithms for Mobile Sensing: from Wireless Sensor Networks to Mobile Crowd Sensing)

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16 pages, 9737 KiB

Open AccessArticle

Development and Sensing Properties Study of Underwater Assembled Water Depth-Inclination Sensors for a Multi-Component Mooring System, Using a Self-Contained Technique

by Wenhua Wu^1,*, Jiaguo Feng², Bin Xie², Da Tang³, Qianjin Yue¹ and Ribin Xie⁴

¹ State Key Laboratory of Structural Analysis for Industrial Equipment, Dalian University of Technology, Dalian 116024, China

² China National Offshore Oil Corporation, Research Institute, Beijing 100028, China

³ Department of Computer Science and Technology, Dalian University of Technology, Dalian 116024, China

⁴ China National Offshore Oil Corporation, Shenzhen Branch, Shenzhen 518000, China

Sensors 2016, 16(11), 1925; https://doi.org/10.3390/s16111925 - 16 Nov 2016

Cited by 12 | Viewed by 4742

Abstract

Prototype monitoring techniques play an important role in the safety guarantee of mooring systems in marine engineering. In general, the complexities of harsh ocean environmental conditions bring difficulties to the traditional monitoring methods of application, implementation and maintenance. Large amounts of existing mooring [...] Read more.

Prototype monitoring techniques play an important role in the safety guarantee of mooring systems in marine engineering. In general, the complexities of harsh ocean environmental conditions bring difficulties to the traditional monitoring methods of application, implementation and maintenance. Large amounts of existing mooring systems still lack valid monitoring strategies. In this paper, an underwater monitoring method which may be used to achieve the mechanical responses of a multi-point catenary mooring system, is present. A novel self-contained assembled water depth-inclination (D-I) sensor is designed and manufactured. Several advanced technologies, such as standalone, low power consumption and synchronism, are considered to satisfy the long-term implementation requirements with low cost during the design process. The design scheme of the water resistance barrel and installation clamp, which satisfies the diver installation, are also provided in the paper. An on-site test has previously been carried out on a production semisubmersible platform in the South China Sea. The prototype data analyses, including the D-I value in the time domain (including the data recorded during the mooring retraction and release process) and spectral characteristics, are presented to reveal the accuracy, feasibility and stability of the sensor in terms of fitting for the prototype monitoring of catenary mooring systems, especially for in-service aging platforms. Full article

(This article belongs to the Section Physical Sensors)

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17 pages, 1694 KiB

Open AccessReview

Methods and Research for Multi-Component Cutting Force Sensing Devices and Approaches in Machining

by Qiaokang Liang^1,2,*

, Dan Zhang^3,4,*, Wanneng Wu^1,2

and Kunlin Zou^1,2

¹ College of Electric and Information Technology, Hunan University, Changsha 410082, China

² State Key Laboratory of Advanced Design and Manufacturing for Vehicle Body, Hunan University, Changsha 410082, China

³ School of Mechanical, Electronic and Control Engineering, Beijing Jiaotong University, Beijing 100044, China

⁴ Department of Mechanical Engineering, York University, Toronto, ON M3J 1P3, Canada

Sensors 2016, 16(11), 1926; https://doi.org/10.3390/s16111926 - 16 Nov 2016

Cited by 31 | Viewed by 9993

Abstract

Multi-component cutting force sensing systems in manufacturing processes applied to cutting tools are gradually becoming the most significant monitoring indicator. Their signals have been extensively applied to evaluate the machinability of workpiece materials, predict cutter breakage, estimate cutting tool wear, control machine tool [...] Read more.

Multi-component cutting force sensing systems in manufacturing processes applied to cutting tools are gradually becoming the most significant monitoring indicator. Their signals have been extensively applied to evaluate the machinability of workpiece materials, predict cutter breakage, estimate cutting tool wear, control machine tool chatter, determine stable machining parameters, and improve surface finish. Robust and effective sensing systems with capability of monitoring the cutting force in machine operations in real time are crucial for realizing the full potential of cutting capabilities of computer numerically controlled (CNC) tools. The main objective of this paper is to present a brief review of the existing achievements in the field of multi-component cutting force sensing systems in modern manufacturing. Full article

(This article belongs to the Special Issue Advanced Robotics and Mechatronics Devices)

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12 pages, 1858 KiB

Open AccessArticle

Development of a Detection Algorithm for Use with Reflectance-Based, Real-Time Chemical Sensing

by Anthony P. Malanoski, Brandy J. Johnson^*

, Jeffrey S. Erickson and David A. Stenger

Center for Bio/Molecular Science & Engineering, Naval Research Laboratory, Washington, DC 20375, USA

Sensors 2016, 16(11), 1927; https://doi.org/10.3390/s16111927 - 16 Nov 2016

Cited by 4 | Viewed by 4604

Abstract

Here, we describe our efforts focused on development of an algorithm for identification of detection events in a real-time sensing application relying on reporting of color values using commercially available color sensing chips. The effort focuses on the identification of event occurrence, rather [...] Read more.

Here, we describe our efforts focused on development of an algorithm for identification of detection events in a real-time sensing application relying on reporting of color values using commercially available color sensing chips. The effort focuses on the identification of event occurrence, rather than target identification, and utilizes approaches suitable to onboard device incorporation to facilitate portable and autonomous use. The described algorithm first excludes electronic noise generated by the sensor system and determines response thresholds. This automatic adjustment provides the potential for use with device variations as well as accommodating differing indicator behaviors. Multiple signal channels (RGB) as well as multiple indicator array elements are combined for reporting of an event with a minimum of false responses. While the method reported was developed for use with paper-supported porphyrin and metalloporphyrin indicators, it should be equally applicable to other colorimetric indicators. Depending on device configurations, receiver operating characteristic (ROC) sensitivities of 1 could be obtained with specificities of 0.87 (threshold 160 ppb, ethanol). Full article

(This article belongs to the Section Chemical Sensors)

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21 pages, 13203 KiB

Open AccessArticle

A Deformable Smart Skin for Continuous Sensing Based on Electrical Impedance Tomography

by Francesco Visentin^1,2,*, Paolo Fiorini² and Kenji Suzuki³

¹ Department of Intelligent Interaction Technologies, University of Tsukuba, Tsukuba 305-8573, Japan

² Department of Computer Science, University of Verona, 37057 Verona, Italy

³ Faculty of Engineering, Information and Systems, University of Tsukuba, Tsukuba 305-8573, Japan

Sensors 2016, 16(11), 1928; https://doi.org/10.3390/s16111928 - 16 Nov 2016

Cited by 34 | Viewed by 7604

Abstract

In this paper, we present a low-cost, adaptable, and flexible pressure sensor that can be applied as a smart skin over both stiff and deformable media. The sensor can be easily adapted for use in applications related to the fields of robotics, rehabilitation, [...] Read more.

In this paper, we present a low-cost, adaptable, and flexible pressure sensor that can be applied as a smart skin over both stiff and deformable media. The sensor can be easily adapted for use in applications related to the fields of robotics, rehabilitation, or costumer electronic devices. In order to remove most of the stiff components that block the flexibility of the sensor, we based the sensing capability on the use of a tomographic technique known as Electrical Impedance Tomography. The technique allows the internal structure of the domain under study to be inferred by reconstructing its conductivity map. By applying the technique to a material that changes its resistivity according to applied forces, it is possible to identify these changes and then localise the area where the force was applied. We tested the system when applied to flat and curved surfaces. For all configurations, we evaluate the artificial skin capabilities to detect forces applied over a single point, over multiple points, and changes in the underlying geometry. The results are all promising, and open the way for the application of such sensors in different robotic contexts where deformability is the key point. Full article

(This article belongs to the Section Physical Sensors)

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19 pages, 1271 KiB

Open AccessArticle

A Theoretical and Empirical Integrated Method to Select the Optimal Combined Signals for Geometry-Free and Geometry-Based Three-Carrier Ambiguity Resolution

by Dongsheng Zhao^1,2,*, Gethin Wyn Roberts^2,3,*

, Lawrence Lau²

, Craig M. Hancock²

and Ruibin Bai⁴

¹ International Doctoral Innovation Center, The University of Nottingham Ningbo China, 199 Taikang East Road, Ningbo 315100, China

² Department of Civil Engineering, The University of Nottingham Ningbo China, 199 Taikang East Road, Ningbo 315100, China

³ Nottingham Geospatial Institute, The University of Nottingham, Triumph Road, Nottingham NG72TU, UK

⁴ School of Computer Science, The University of Nottingham Ningbo China, 199 Taikang East Road, Ningbo 315100, China

Sensors 2016, 16(11), 1929; https://doi.org/10.3390/s16111929 - 16 Nov 2016

Cited by 6 | Viewed by 4717

Abstract

Twelve GPS Block IIF satellites, out of the current constellation, can transmit on three-frequency signals (L1, L2, L5). Taking advantages of these signals, Three-Carrier Ambiguity Resolution (TCAR) is expected to bring much benefit for ambiguity resolution. One of the research areas is to [...] Read more.

Twelve GPS Block IIF satellites, out of the current constellation, can transmit on three-frequency signals (L1, L2, L5). Taking advantages of these signals, Three-Carrier Ambiguity Resolution (TCAR) is expected to bring much benefit for ambiguity resolution. One of the research areas is to find the optimal combined signals for a better ambiguity resolution in geometry-free (GF) and geometry-based (GB) mode. However, the existing researches select the signals through either pure theoretical analysis or testing with simulated data, which might be biased as the real observation condition could be different from theoretical prediction or simulation. In this paper, we propose a theoretical and empirical integrated method, which first selects the possible optimal combined signals in theory and then refines these signals with real triple-frequency GPS data, observed at eleven baselines of different lengths. An interpolation technique is also adopted in order to show changes of the AR performance with the increase in baseline length. The results show that the AR success rate can be improved by 3% in GF mode and 8% in GB mode at certain intervals of the baseline length. Therefore, the TCAR can perform better by adopting the combined signals proposed in this paper when the baseline meets the length condition. Full article

(This article belongs to the Section Remote Sensors)

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18 pages, 2323 KiB

Open AccessArticle

Approach for Self-Calibrating CO₂ Measurements with Linear Membrane-Based Gas Sensors

by Detlef Lazik^* and Pramit Sood

Helmholtz Centre for Environmental Research—UFZ, Theodor-Lieser-Strasse 4, Halle (Saale) D-06120, Germany

Sensors 2016, 16(11), 1930; https://doi.org/10.3390/s16111930 - 17 Nov 2016

Cited by 3 | Viewed by 4973

Abstract

Linear membrane-based gas sensors that can be advantageously applied for the measurement of a single gas component in large heterogeneous systems, e.g., for representative determination of CO₂ in the subsurface, can be designed depending on the properties of the observation object. A [...] Read more.

Linear membrane-based gas sensors that can be advantageously applied for the measurement of a single gas component in large heterogeneous systems, e.g., for representative determination of CO₂ in the subsurface, can be designed depending on the properties of the observation object. A resulting disadvantage is that the permeation-based sensor response depends on operating conditions, the individual site-adapted sensor geometry, the membrane material, and the target gas component. Therefore, calibration is needed, especially of the slope, which could change over several orders of magnitude. A calibration-free approach based on an internal gas standard is developed to overcome the multi-criterial slope dependency. This results in a normalization of sensor response and enables the sensor to assess the significance of measurement. The approach was proofed on the example of CO₂ analysis in dry air with tubular PDMS membranes for various CO₂ concentrations of an internal standard. Negligible temperature dependency was found within an 18 K range. The transformation behavior of the measurement signal and the influence of concentration variations of the internal standard on the measurement signal were shown. Offsets that were adjusted based on the stated theory for the given measurement conditions and material data from the literature were in agreement with the experimentally determined offsets. A measurement comparison with an NDIR reference sensor shows an unexpectedly low bias (<1%) of the non-calibrated sensor response, and comparable statistical uncertainty. Full article

(This article belongs to the Section Chemical Sensors)

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17 pages, 2185 KiB

Open AccessReview

Nano-Engineered Biomimetic Optical Sensors for Glucose Monitoring in Diabetes

by Sajid Rauf¹, Muhammad Azhar Hayat Nawaz¹, Mihaela Badea²

, Jean Louis Marty^3,* and Akhtar Hayat^1,3,*

¹ Interdisciplinary Research Centre in Biomedical Materials (IRCBM), COMSATS Institute of Information Technology, 54000 Lahore, Pakistan

² Faculty of Medicine, Transilvania University of Brasov, 500019 Brasov, Romania

³ BAE Laboratory, Universite de Perpignan Via Domitia, 66860 Perpignan, France

Sensors 2016, 16(11), 1931; https://doi.org/10.3390/s16111931 - 17 Nov 2016

Cited by 34 | Viewed by 10279

Abstract

Diabetes is a rapidly growing disease that can be monitored at an individual level by controlling the blood glucose level, hence minimizing the negative impact of the disease. Significant research efforts have been focused on the design of novel and improved technologies to [...] Read more.

Diabetes is a rapidly growing disease that can be monitored at an individual level by controlling the blood glucose level, hence minimizing the negative impact of the disease. Significant research efforts have been focused on the design of novel and improved technologies to overcome the limitations of existing glucose analysis methods. In this context, nanotechnology has enabled the diagnosis at the single cell and molecular level with the possibility of incorporation in advanced molecular diagnostic biochips. Recent years have witnessed the exploration and synthesis of various types of nanomaterials with enzyme-like properties, with their subsequent integration into the design of biomimetic optical sensors for glucose monitoring. This review paper will provide insights on the type, nature and synthesis of different biomimetic nanomaterials. Moreover, recent developments in the integration of these nanomaterials for optical glucose biosensing will be highlighted, with a final discussion on the challenges that must be addressed for successful implementation of these nano-devices in the clinical applications is presented. Full article

(This article belongs to the Special Issue Nanobiosensing for Sensors)

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27 pages, 6366 KiB

Open AccessArticle

Simulation of Attacks for Security in Wireless Sensor Network

by Alvaro Diaz^*

and Pablo Sanchez

Microelectronics Engineering Group, University of Cantabria, 39011 Cantabria, Spain

Sensors 2016, 16(11), 1932; https://doi.org/10.3390/s16111932 - 18 Nov 2016

Cited by 49 | Viewed by 14986

Abstract

The increasing complexity and low-power constraints of current Wireless Sensor Networks (WSN) require efficient methodologies for network simulation and embedded software performance analysis of nodes. In addition, security is also a very important feature that has to be addressed in most WSNs, since [...] Read more.

The increasing complexity and low-power constraints of current Wireless Sensor Networks (WSN) require efficient methodologies for network simulation and embedded software performance analysis of nodes. In addition, security is also a very important feature that has to be addressed in most WSNs, since they may work with sensitive data and operate in hostile unattended environments. In this paper, a methodology for security analysis of Wireless Sensor Networks is presented. The methodology allows designing attack-aware embedded software/firmware or attack countermeasures to provide security in WSNs. The proposed methodology includes attacker modeling and attack simulation with performance analysis (node’s software execution time and power consumption estimation). After an analysis of different WSN attack types, an attacker model is proposed. This model defines three different types of attackers that can emulate most WSN attacks. In addition, this paper presents a virtual platform that is able to model the node hardware, embedded software and basic wireless channel features. This virtual simulation analyzes the embedded software behavior and node power consumption while it takes into account the network deployment and topology. Additionally, this simulator integrates the previously mentioned attacker model. Thus, the impact of attacks on power consumption and software behavior/execution-time can be analyzed. This provides developers with essential information about the effects that one or multiple attacks could have on the network, helping them to develop more secure WSN systems. This WSN attack simulator is an essential element of the attack-aware embedded software development methodology that is also introduced in this work. Full article

(This article belongs to the Special Issue Trusted and Secure Wireless Sensor Network Designs and Deployments)

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10 pages, 3190 KiB

Open AccessArticle

Full-Field Optical Coherence Tomography Using Galvo Filter-Based Wavelength Swept Laser

by Muhammad Faizan Shirazi¹

, Pilun Kim², Mansik Jeon^1,* and Jeehyun Kim^1,2

¹ School of Electronics Engineering, College of IT Engineering, Kyungpook National University, 80 Daehak-ro, Bukgu, 41566 Daegu, Korea

² Oz-Tec Co. Ltd., Office 901, IT Convergence Industrial Building, 47 Gyeongdae-ro, 17-gil, Bukgu, 41566 Daegu, Korea

Sensors 2016, 16(11), 1933; https://doi.org/10.3390/s16111933 - 17 Nov 2016

Cited by 7 | Viewed by 7629

Abstract

We report a wavelength swept laser-based full-field optical coherence tomography for measuring the surfaces and thicknesses of refractive and reflective samples. The system consists of a galvo filter–based wavelength swept laser and a simple Michelson interferometer. Combinations of the reflective and refractive samples [...] Read more.

We report a wavelength swept laser-based full-field optical coherence tomography for measuring the surfaces and thicknesses of refractive and reflective samples. The system consists of a galvo filter–based wavelength swept laser and a simple Michelson interferometer. Combinations of the reflective and refractive samples are used to demonstrate the performance of the system. By synchronizing the camera with the source, the cross-sectional information of the samples can be seen after each sweep of the swept source. This system can be effective for the thickness measurement of optical thin films as well as for the depth investigation of samples in industrial applications. A resolution target with a glass cover slip and a step height standard target are imaged, showing the cross-sectional and topographical information of the samples. Full article

(This article belongs to the Special Issue Imaging: Sensors and Technologies)

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26 pages, 5253 KiB

Open AccessArticle

A Node Localization Algorithm Based on Multi-Granularity Regional Division and the Lagrange Multiplier Method in Wireless Sensor Networks

by Fengjun Shang^*, Yi Jiang, Anping Xiong, Wen Su and Li He

College of Computer Science and Technology, Chongqing University of Posts and Telecommunications, Chongqing 400065, China

Sensors 2016, 16(11), 1934; https://doi.org/10.3390/s16111934 - 18 Nov 2016

Cited by 14 | Viewed by 7233

Abstract

With the integrated development of the Internet, wireless sensor technology, cloud computing, and mobile Internet, there has been a lot of attention given to research about and applications of the Internet of Things. A Wireless Sensor Network (WSN) is one of the important [...] Read more.

With the integrated development of the Internet, wireless sensor technology, cloud computing, and mobile Internet, there has been a lot of attention given to research about and applications of the Internet of Things. A Wireless Sensor Network (WSN) is one of the important information technologies in the Internet of Things; it integrates multi-technology to detect and gather information in a network environment by mutual cooperation, using a variety of methods to process and analyze data, implement awareness, and perform tests. This paper mainly researches the localization algorithm of sensor nodes in a wireless sensor network. Firstly, a multi-granularity region partition is proposed to divide the location region. In the range-based method, the RSSI (Received Signal Strength indicator, RSSI) is used to estimate distance. The optimal RSSI value is computed by the Gaussian fitting method. Furthermore, a Voronoi diagram is characterized by the use of dividing region. Rach anchor node is regarded as the center of each region; the whole position region is divided into several regions and the sub-region of neighboring nodes is combined into triangles while the unknown node is locked in the ultimate area. Secondly, the multi-granularity regional division and Lagrange multiplier method are used to calculate the final coordinates. Because nodes are influenced by many factors in the practical application, two kinds of positioning methods are designed. When the unknown node is inside positioning unit, we use the method of vector similarity. Moreover, we use the centroid algorithm to calculate the ultimate coordinates of unknown node. When the unknown node is outside positioning unit, we establish a Lagrange equation containing the constraint condition to calculate the first coordinates. Furthermore, we use the Taylor expansion formula to correct the coordinates of the unknown node. In addition, this localization method has been validated by establishing the real environment. Full article

(This article belongs to the Special Issue Sensors for Agriculture)

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19 pages, 3865 KiB

Open AccessArticle

Real-Time Lane Region Detection Using a Combination of Geometrical and Image Features

by Danilo Cáceres Hernández, Laksono Kurnianggoro, Alexander Filonenko

and Kang Hyun Jo^*

Intelligent Systems Laboratory, Graduate School of Electrical Engineering, University of Ulsan, Ulsan 44610, Korea

Sensors 2016, 16(11), 1935; https://doi.org/10.3390/s16111935 - 17 Nov 2016

Cited by 31 | Viewed by 8194

Abstract

Over the past few decades, pavement markings have played a key role in intelligent vehicle applications such as guidance, navigation, and control. However, there are still serious issues facing the problem of lane marking detection. For example, problems include excessive processing time and [...] Read more.

Over the past few decades, pavement markings have played a key role in intelligent vehicle applications such as guidance, navigation, and control. However, there are still serious issues facing the problem of lane marking detection. For example, problems include excessive processing time and false detection due to similarities in color and edges between traffic signs (channeling lines, stop lines, crosswalk, arrows, etc.). This paper proposes a strategy to extract the lane marking information taking into consideration its features such as color, edge, and width, as well as the vehicle speed. Firstly, defining the region of interest is a critical task to achieve real-time performance. In this sense, the region of interest is dependent on vehicle speed. Secondly, the lane markings are detected by using a hybrid color-edge feature method along with a probabilistic method, based on distance-color dependence and a hierarchical fitting model. Thirdly, the following lane marking information is extracted: the number of lane markings to both sides of the vehicle, the respective fitting model, and the centroid information of the lane. Using these parameters, the region is computed by using a road geometric model. To evaluate the proposed method, a set of consecutive frames was used in order to validate the performance. Full article

(This article belongs to the Special Issue Sensors for Autonomous Road Vehicles)

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22 pages, 11354 KiB

Open AccessArticle

Multi-Axis Force/Torque Sensor Based on Simply-Supported Beam and Optoelectronics

by Yohan Noh^1,2,*, Joao Bimbo³

, Sina Sareh⁴, Helge Wurdemann⁵, Jan Fraś⁶, Damith Suresh Chathuranga⁷

, Hongbin Liu¹, James Housden², Kaspar Althoefer⁸ and Kawal Rhode²

¹ Department of Informatics, King’s College London, London WC2R 2LS, UK

² Department of Biomedical Engineering, King’s College London, London SE1 7EH, UK

³ Instituto Italiano di Tecnologia (IIT), Genova 16163, Italy

⁴ Department of Aeronautics, Imperial College London, London SW7 2AZ, UK

⁵ Department of Mechanical Engineering, University College London, London WC1E 7JE, UK

⁶ Industrial Research Institute for Automation and Measurements, Warsaw 02-486, Poland

⁷ Department of Mechanical Engineering, University of Moratuwa, Katubadda, Moratuwa 10400, Sri Lanka

⁸ ARQ—Advanced Robotics @ Queen Mary Faculty of Science and Engineering Queen Mary University of London, Mile End Rd, London E1 4NS, UK

Sensors 2016, 16(11), 1936; https://doi.org/10.3390/s16111936 - 17 Nov 2016

Cited by 55 | Viewed by 21206

Abstract

This paper presents a multi-axis force/torque sensor based on simply-supported beam and optoelectronic technology. The sensor’s main advantages are: (1) Low power consumption; (2) low-level noise in comparison with conventional methods of force sensing (e.g., using strain gauges); (3) the ability to be [...] Read more.

This paper presents a multi-axis force/torque sensor based on simply-supported beam and optoelectronic technology. The sensor’s main advantages are: (1) Low power consumption; (2) low-level noise in comparison with conventional methods of force sensing (e.g., using strain gauges); (3) the ability to be embedded into different mechanical structures; (4) miniaturisation; (5) simple manufacture and customisation to fit a wide-range of robot systems; and (6) low-cost fabrication and assembly of sensor structure. For these reasons, the proposed multi-axis force/torque sensor can be used in a wide range of application areas including medical robotics, manufacturing, and areas involving human–robot interaction. This paper shows the application of our concept of a force/torque sensor to flexible continuum manipulators: A cylindrical MIS (Minimally Invasive Surgery) robot, and includes its design, fabrication, and evaluation tests. Full article

(This article belongs to the Section Physical Sensors)

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21 pages, 4754 KiB

Open AccessArticle

Analysis of Multi-Antenna GNSS Receiver Performance under Jamming Attacks

by Niranjana Vagle^*, Ali Broumandan and Gérard Lachapelle

PLAN Group, Department of Geomatics Engineering, Schulich School of Engineering, University of Calgary, 2500 University Drive N. W., Calgary, AB T2N 1N4, Canada

Sensors 2016, 16(11), 1937; https://doi.org/10.3390/s16111937 - 17 Nov 2016

Cited by 11 | Viewed by 6405

Abstract

Although antenna array-based Global Navigation Satellite System (GNSS) receivers can be used to mitigate both narrowband and wideband electronic interference sources, measurement distortions induced by array processing methods are not suitable for high precision applications. The measurement distortions have an adverse effect on [...] Read more.

Although antenna array-based Global Navigation Satellite System (GNSS) receivers can be used to mitigate both narrowband and wideband electronic interference sources, measurement distortions induced by array processing methods are not suitable for high precision applications. The measurement distortions have an adverse effect on the carrier phase ambiguity resolution, affecting the navigation solution. Depending on the array attitude information availability and calibration parameters, different spatial processing methods can be implemented although they distort carrier phase measurements in some cases. This paper provides a detailed investigation of the effect of different array processing techniques on array-based GNSS receiver measurements and navigation performance. The main novelty of the paper is to provide a thorough analysis of array-based GNSS receivers employing different beamforming techniques from tracking to navigation solution. Two beamforming techniques, namely Power Minimization (PM) and Minimum Power Distortionless Response (MPDR), are being investigated. In the tracking domain, the carrier Doppler, Phase Lock Indicator (PLI), and Carrier-to-Noise Ratio (C/N₀) are analyzed. Pseudorange and carrier phase measurement distortions and carrier phase position performance are also evaluated. Performance analyses results from simulated GNSS signals and field tests are provided. Full article

(This article belongs to the Section Physical Sensors)

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14 pages, 4115 KiB

Open AccessArticle

Validation of Remote Sensing Retrieval Products using Data from a Wireless Sensor-Based Online Monitoring in Antarctica

by Xiuhong Li^1,2, Xiao Cheng^1,2

, Rongjin Yang^3,*, Qiang Liu^1,2

, Yubao Qiu⁴, Jialin Zhang¹, Erli Cai¹ and Long Zhao¹

¹ College of Global Change and Earth System Science, Beijing Normal University, No. 19, Xin Jie Kou Wai Street, Beijing 100875, China

² Joint Center for Global Change Studies, Beijing 100875, China

³ State Key Laboratory of Environmental Criteria and Risk Assessment, Chinese Research Academy of Environmental Sciences, No. 8, Da Yang Fang, An Wai, Chao Yang, Beijing 100012, China

⁴ Institute of Remote Sensing and Digital Earth of Chinese Academy of Sciences, Beijing 100101, China

Sensors 2016, 16(11), 1938; https://doi.org/10.3390/s16111938 - 17 Nov 2016

Cited by 7 | Viewed by 4826

Abstract

Of the modern technologies in polar-region monitoring, the remote sensing technology that can instantaneously form large-scale images has become much more important in helping acquire parameters such as the freezing and melting of ice as well as the surface temperature, which can be [...] Read more.

Of the modern technologies in polar-region monitoring, the remote sensing technology that can instantaneously form large-scale images has become much more important in helping acquire parameters such as the freezing and melting of ice as well as the surface temperature, which can be used in the research of global climate change, Antarctic ice sheet responses, and cap formation and evolution. However, the acquirement of those parameters is impacted remarkably by the climate and satellite transit time which makes it almost impossible to have timely and continuous observation data. In this research, a wireless sensor-based online monitoring platform (WSOOP) for the extreme polar environment is applied to obtain a long-term series of data which is site-specific and continuous in time. Those data are compared and validated with the data from a weather station at Zhongshan Station Antarctica and the result shows an obvious correlation. Then those data are used to validate the remote sensing products of the freezing and melting of ice and the surface temperature and the result also indicated a similar correlation. The experiment in Antarctica has proven that WSOOP is an effective system to validate remotely sensed data in the polar region. Full article

(This article belongs to the Section Remote Sensors)

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12 pages, 1406 KiB

Open AccessArticle

Compressed Symmetric Nested Arrays and Their Application for Direction-of-Arrival Estimation of Near-Field Sources

by Shuang Li^1,*

and Dongfeng Xie²

¹ School of Electrical and Electronic Engineering, Chongqing University of Technology, Chongqing 400054, China

² Shanghai Huawei Technologies Co., Ltd., Shanghai 200120, China

Sensors 2016, 16(11), 1939; https://doi.org/10.3390/s16111939 - 17 Nov 2016

Cited by 22 | Viewed by 4410

Abstract

In this paper, a new sensor array geometry, called a compressed symmetric nested array (CSNA), is designed to increase the degrees of freedom in the near field. As its name suggests, a CSNA is constructed by getting rid of some elements from two [...] Read more.

In this paper, a new sensor array geometry, called a compressed symmetric nested array (CSNA), is designed to increase the degrees of freedom in the near field. As its name suggests, a CSNA is constructed by getting rid of some elements from two identical nested arrays. The closed form expressions are also presented for the sensor locations and the largest degrees of freedom obtainable as a function of the total number of sensors. Furthermore, a novel DOA estimation method is proposed by utilizing the CSNA in the near field. By employing this new array geometry, our method can identify more sources than sensors. Compared with other existing methods, the proposed method achieves higher resolution because of increased array aperture. Simulation results are demonstrated to verify the effectiveness of the proposed method. Full article

(This article belongs to the Section Physical Sensors)

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18 pages, 5425 KiB

Open AccessArticle

Virtual Distances Methodology as Verification Technique for AACMMs with a Capacitive Sensor Based Indexed Metrology Platform

by Raquel Acero^1,*

, Jorge Santolaria²

, Agustin Brau³

and Marcos Pueo¹

¹ Centro Universitario de la Defensa, Academia General Militar, Ctra. Huesca s/n, Zaragoza 50090, Spain

² Department of Design and Manufacturing Engineering, University of Zaragoza, María de Luna 3, Zaragoza 50018, Spain

³ Department of Industrial Engineering, University of Sonora, Rosales y Blvd. Luis Encinas s/n, Hermosillo 83000, Sonora, Mexico

Sensors 2016, 16(11), 1940; https://doi.org/10.3390/s16111940 - 18 Nov 2016

Cited by 12 | Viewed by 5262

Abstract

This paper presents a new verification procedure for articulated arm coordinate measuring machines (AACMMs) together with a capacitive sensor-based indexed metrology platform (IMP) based on the generation of virtual reference distances. The novelty of this procedure lays on the possibility of creating virtual [...] Read more.

This paper presents a new verification procedure for articulated arm coordinate measuring machines (AACMMs) together with a capacitive sensor-based indexed metrology platform (IMP) based on the generation of virtual reference distances. The novelty of this procedure lays on the possibility of creating virtual points, virtual gauges and virtual distances through the indexed metrology platform’s mathematical model taking as a reference the measurements of a ball bar gauge located in a fixed position of the instrument’s working volume. The measurements are carried out with the AACMM assembled on the IMP from the six rotating positions of the platform. In this way, an unlimited number and types of reference distances could be created without the need of using a physical gauge, therefore optimizing the testing time, the number of gauge positions and the space needed in the calibration and verification procedures. Four evaluation methods are presented to assess the volumetric performance of the AACMM. The results obtained proved the suitability of the virtual distances methodology as an alternative procedure for verification of AACMMs using the indexed metrology platform. Full article

(This article belongs to the Section Physical Sensors)

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20 pages, 6312 KiB

Open AccessArticle

Wireless Mid-Infrared Spectroscopy Sensor Network for Automatic Carbon Dioxide Fertilization in a Greenhouse Environment

by Jianing Wang¹, Xintao Niu¹, Lingjiao Zheng¹, Chuantao Zheng^1,2,* and Yiding Wang^1,*

¹ State Key Laboratory on Integrated Optoelectronics, College of Electronic Science and Engineering, Jilin University, Changchun 130012, China

² Electrical and Computer Engineering Department, Rice University, 6100 Main Street, Houston 77005, TX, USA

Sensors 2016, 16(11), 1941; https://doi.org/10.3390/s16111941 - 18 Nov 2016

Cited by 32 | Viewed by 8816

Abstract

In this paper, a wireless mid-infrared spectroscopy sensor network was designed and implemented for carbon dioxide fertilization in a greenhouse environment. A mid-infrared carbon dioxide (CO₂) sensor based on non-dispersive infrared (NDIR) with the functionalities of wireless communication and anti-condensation prevention [...] Read more.

In this paper, a wireless mid-infrared spectroscopy sensor network was designed and implemented for carbon dioxide fertilization in a greenhouse environment. A mid-infrared carbon dioxide (CO₂) sensor based on non-dispersive infrared (NDIR) with the functionalities of wireless communication and anti-condensation prevention was realized as the sensor node. Smart transmission power regulation was applied in the wireless sensor network, according to the Received Signal Strength Indication (RSSI), to realize high communication stability and low-power consumption deployment. Besides real-time monitoring, this system also provides a CO₂ control facility for manual and automatic control through a LabVIEW platform. According to simulations and field tests, the implemented sensor node has a satisfying anti-condensation ability and reliable measurement performance on CO₂ concentrations ranging from 30 ppm to 5000 ppm. As an application, based on the Fuzzy proportional, integral, and derivative (PID) algorithm realized on a LabVIEW platform, the CO₂ concentration was regulated to some desired concentrations, such as 800 ppm and 1200 ppm, in 30 min with a controlled fluctuation of <±35 ppm in an acre of greenhouse. Full article

(This article belongs to the Section Physical Sensors)

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16 pages, 5497 KiB

Open AccessArticle

Ex-Vivo Characterization of Bioimpedance Spectroscopy of Normal, Ischemic and Hemorrhagic Rabbit Brain Tissue at Frequencies from 10 Hz to 1 MHz

by Lin Yang^†, Ge Zhang^†, Jiali Song, Meng Dai, Canhua Xu, Xiuzhen Dong and Feng Fu^*

¹ Department of Biomedical Engineering, Fourth Military Medical University, Xi’an 710032, China

^† These authors contributed equally to this work.

Sensors 2016, 16(11), 1942; https://doi.org/10.3390/s16111942 - 18 Nov 2016

Cited by 34 | Viewed by 6982

Abstract

Stroke is a severe cerebrovascular disease and is the second greatest cause of death worldwide. Because diagnostic tools (CT and MRI) to detect acute stroke cannot be used until the patient reaches the hospital setting, a portable diagnostic tool is urgently needed. Because [...] Read more.

Stroke is a severe cerebrovascular disease and is the second greatest cause of death worldwide. Because diagnostic tools (CT and MRI) to detect acute stroke cannot be used until the patient reaches the hospital setting, a portable diagnostic tool is urgently needed. Because biological tissues have different impedance spectra under normal physiological conditions and different pathological states, multi-frequency electrical impedance tomography (MFEIT) can potentially detect stroke. Accurate impedance spectra of normal brain tissue (gray and white matter) and stroke lesions (ischemic and hemorrhagic tissue) are important elements when studying stroke detection with MFEIT. To our knowledge, no study has comprehensively measured the impedance spectra of normal brain tissue and stroke lesions for the whole frequency range of 1 MHz within as short as possible an ex vivo time and using the same animal model. In this study, we established intracerebral hemorrhage and ischemic models in rabbits, then measured and analyzed the impedance spectra of normal brain tissue and stroke lesions ex vivo within 15 min after animal death at 10 Hz to 1 MHz. The results showed that the impedance spectra of stroke lesions significantly differed from those of normal brain tissue; the ratio of change in impedance of ischemic and hemorrhagic tissue with regard to frequency was distinct; and tissue type could be discriminated according to its impedance spectra. These findings further confirm the feasibility of detecting stroke with MFEIT and provide data supporting further study of MFEIT to detect stroke. Full article

(This article belongs to the Section Biosensors)

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22 pages, 2553 KiB

Open AccessArticle

The Development of a Gas–Liquid Two-Phase Flow Sensor Applicable to CBM Wellbore Annulus

by Chuan Wu¹, Guojun Wen^2,*, Lei Han² and Xiaoming Wu¹

¹ Faculty of Engineering, China University of Geosciences (Wuhan), Wuhan 430074, China

² Faculty of Mechanical and Electronic Information, China University of Geosciences (Wuhan), Wuhan 430074, China

Sensors 2016, 16(11), 1943; https://doi.org/10.3390/s16111943 - 18 Nov 2016

Cited by 11 | Viewed by 6269

Abstract

The measurement of wellbore annulus gas–liquid two-phase flow in CBM (coalbed methane) wells is of great significance for reasonably developing gas drainage and extraction processes, estimating CBM output, judging the operating conditions of CBM wells and analyzing stratum conditions. Hence, a specially designed [...] Read more.

The measurement of wellbore annulus gas–liquid two-phase flow in CBM (coalbed methane) wells is of great significance for reasonably developing gas drainage and extraction processes, estimating CBM output, judging the operating conditions of CBM wells and analyzing stratum conditions. Hence, a specially designed sensor is urgently needed for real-time measurement of gas–liquid two-phase flow in CBM wellbore annulus. Existing flow sensors fail to meet the requirements of the operating conditions of CBM wellbore annulus due to such factors as an inapplicable measurement principle, larger size, poor sealability, high installation accuracy, and higher requirements for fluid media. Therefore, based on the principle of a target flowmeter, this paper designs a new two-phase flow sensor that can identify and automatically calibrate different flow patterns of two-phase flows. Upon the successful development of the new flow sensor, lab and field tests were carried out, and the results show that the newly designed sensor, with a measurement accuracy of ±2.5%, can adapt to the operating conditions of CBM wells and is reliable for long-term work. Full article

(This article belongs to the Section Physical Sensors)

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10 pages, 2500 KiB

Open AccessArticle

Dew Point Calibration System Using a Quartz Crystal Sensor with a Differential Frequency Method

by Ningning Lin, Xiaofeng Meng and Jing Nie^*

Science and Technology on Inertial Laboratory, Beihang University, Beijing 100191, China

Sensors 2016, 16(11), 1944; https://doi.org/10.3390/s16111944 - 18 Nov 2016

Cited by 8 | Viewed by 5502

Abstract

In this paper, the influence of temperature on quartz crystal microbalance (QCM) sensor response during dew point calibration is investigated. The aim is to present a compensation method to eliminate temperature impact on frequency acquisition. A new sensitive structure is proposed with double [...] Read more.

In this paper, the influence of temperature on quartz crystal microbalance (QCM) sensor response during dew point calibration is investigated. The aim is to present a compensation method to eliminate temperature impact on frequency acquisition. A new sensitive structure is proposed with double QCMs. One is kept in contact with the environment, whereas the other is not exposed to the atmosphere. There is a thermal conductivity silicone pad between each crystal and a refrigeration device to keep a uniform temperature condition. A differential frequency method is described in detail and is applied to calibrate the frequency characteristics of QCM at the dew point of −3.75 °C. It is worth noting that frequency changes of two QCMs were approximately opposite when temperature conditions were changed simultaneously. The results from continuous experiments show that the frequencies of two QCMs as the dew point moment was reached have strong consistency and high repeatability, leading to the conclusion that the sensitive structure can calibrate dew points with high reliability. Full article

(This article belongs to the Section Physical Sensors)

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7 pages, 1209 KiB

Open AccessArticle

Quencher-Free Fluorescence Method for the Detection of Mercury(II) Based on Polymerase-Aided Photoinduced Electron Transfer Strategy

by Haisheng Liu¹, Linbin Ma², Changbei Ma^1,*, Junyan Du¹, Meilan Wang² and Kemin Wang³

¹ State Key Laboratory of Medical Genetics & School of Life Sciences, Central South University, Changsha 410013, China

² Department of Environmental Monitoring, Changsha Environmental Protection Technology Vocational College, Changsha 410004, China

³ State Key Laboratory of Chemo/Biosensing and Chemometrics, Hunan University, Changsha 410081, China

Sensors 2016, 16(11), 1945; https://doi.org/10.3390/s16111945 - 18 Nov 2016

Cited by 17 | Viewed by 5571

Abstract

A new quencher-free Hg²⁺ ion assay method was developed based on polymerase-assisted photoinduced electron transfer (PIET). In this approach, a probe is designed with a mercury ion recognition sequence (MRS) that is composed of two T-rich functional areas separated by a spacer [...] Read more.

A new quencher-free Hg²⁺ ion assay method was developed based on polymerase-assisted photoinduced electron transfer (PIET). In this approach, a probe is designed with a mercury ion recognition sequence (MRS) that is composed of two T-rich functional areas separated by a spacer of random bases at the 3′-end, and a sequence of stacked cytosines at the 5′-end, to which a fluorescein (FAM) is attached. Upon addition of Hg²⁺ ions into this sensing system, the MRS folds into a hairpin structure at the 3′-end with Hg²⁺-mediated base pairs. In the presence of DNA polymerase, it will catalyze the extension reaction, resulting in the formation of stacked guanines, which will instantly quench the fluorescence of FAM through PIET. Under optimal conditions, the limit of detection for Hg²⁺ ions was estimated to be 5 nM which is higher than the US Environmental Protection Agency (EPA) standard limit. In addition, no labeling with a quencher was requiring, and the present method is fairly simple, fast and low cost. It is expected that this cost-effective fluorescence method might hold considerable potential in the detection of Hg²⁺ ions in real biological and environmental samples. Full article

(This article belongs to the Special Issue Sensors for Environmental Monitoring 2016)

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15 pages, 3169 KiB

Open AccessArticle

Highly Sensitive and Practical Detection of Plant Viruses via Electrical Impedance of Droplets on Textured Silicon-Based Devices

by Marianna Ambrico^1,*, Paolo Francesco Ambrico¹

, Angelantonio Minafra², Angelo De Stradis², Danilo Vona³, Stefania R. Cicco⁴

, Fabio Palumbo¹

, Pietro Favia³ and Teresa Ligonzo⁵

¹ CNR NANOTEC—Istituto di Nanotecnologia, Via Amendola 122, Bari 70126, Italy

² CNR IPSP—Istituto per la Protezione Sostenibile delle Piante, UoS Bari, Via Amendola 165, Bari 70126, Italy

³ Dipartimento di Chimica, Università degli Studi di Bari, Via Orabona 4, Bari 70125, Italy

⁴ CNR ICCOM—Istituto di Chimica dei Composti OrganoMetallici, Via Orabona 4, Bari 70125, Italy

⁵ Dipartimento Interateneo di Fisica, Università degli Studi di Bari, Via Orabona 4, Bari 70125, Italy

Sensors 2016, 16(11), 1946; https://doi.org/10.3390/s16111946 - 18 Nov 2016

Cited by 12 | Viewed by 6814

Abstract

Early diagnosis of plant virus infections before the disease symptoms appearance may represent a significant benefit in limiting disease spread by a prompt application of appropriate containment steps. We propose a label-free procedure applied on a device structure where the electrical signal transduction [...] Read more.

Early diagnosis of plant virus infections before the disease symptoms appearance may represent a significant benefit in limiting disease spread by a prompt application of appropriate containment steps. We propose a label-free procedure applied on a device structure where the electrical signal transduction is evaluated via impedance spectroscopy techniques. The device consists of a droplet suspension embedding two representative purified plant viruses i.e., Tomato mosaic virus and Turnip yellow mosaic virus, put in contact with a highly hydrophobic plasma textured silicon surface. Results show a high sensitivity of the system towards the virus particles with an interestingly low detection limit, from tens to hundreds of attomolar corresponding to pg/mL of sap, which refers, in the infection time-scale, to a concentration of virus particles in still-symptomless plants. Such a threshold limit, together with an envisaged engineering of an easily manageable device, compared to more sophisticated apparatuses, may contribute in simplifying the in-field plant virus diagnostics. Full article

(This article belongs to the Special Issue Nanobiosensing for Sensors)

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24 pages, 3790 KiB

Open AccessArticle

Context-Aware Fusion of RGB and Thermal Imagery for Traffic Monitoring

by Thiemo Alldieck, Chris H. Bahnsen^* and Thomas B. Moeslund

Visual Analysis of People Lab, Aalborg University, 9000 Aalborg, Denmark

Sensors 2016, 16(11), 1947; https://doi.org/10.3390/s16111947 - 18 Nov 2016

Cited by 42 | Viewed by 7348

Abstract

In order to enable a robust 24-h monitoring of traffic under changing environmental conditions, it is beneficial to observe the traffic scene using several sensors, preferably from different modalities. To fully benefit from multi-modal sensor output, however, one must fuse the data. This [...] Read more.

In order to enable a robust 24-h monitoring of traffic under changing environmental conditions, it is beneficial to observe the traffic scene using several sensors, preferably from different modalities. To fully benefit from multi-modal sensor output, however, one must fuse the data. This paper introduces a new approach for fusing color RGB and thermal video streams by using not only the information from the videos themselves, but also the available contextual information of a scene. The contextual information is used to judge the quality of a particular modality and guides the fusion of two parallel segmentation pipelines of the RGB and thermal video streams. The potential of the proposed context-aware fusion is demonstrated by extensive tests of quantitative and qualitative characteristics on existing and novel video datasets and benchmarked against competing approaches to multi-modal fusion. Full article

(This article belongs to the Special Issue Advances in Multi-Sensor Information Fusion: Theory and Applications)

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20 pages, 14780 KiB

Open AccessArticle

Extracting Plant Phenology Metrics in a Great Basin Watershed: Methods and Considerations for Quantifying Phenophases in a Cold Desert

by Keirith A. Snyder^1,*, Bryce L. Wehan¹, Gianluca Filippa²

, Justin L. Huntington³, Tamzen K. Stringham⁴

and Devon K. Snyder⁴

¹ USDA-ARS, Great Basin Rangelands Research Unit, Reno, NV 89512, USA

² Environmental Protection Agency of Aosta Valley, ARPA Valle d’Aosta, Climate Change Unit, Saint-christophe 11020, Italy

³ Western Regional Climate Center, Desert Research Institute, Reno, NV 89512, USA

⁴ Department of Agriculture, Nutrition and Veterinary Science, University of Nevada, Reno, NV 89557, USA

Sensors 2016, 16(11), 1948; https://doi.org/10.3390/s16111948 - 18 Nov 2016

Cited by 22 | Viewed by 7404

Abstract

Plant phenology is recognized as important for ecological dynamics. There has been a recent advent of phenology and camera networks worldwide. The established PhenoCam Network has sites in the United States, including the western states. However, there is a paucity of published research [...] Read more.

Plant phenology is recognized as important for ecological dynamics. There has been a recent advent of phenology and camera networks worldwide. The established PhenoCam Network has sites in the United States, including the western states. However, there is a paucity of published research from semi-arid regions. In this study, we demonstrate the utility of camera-based repeat digital imagery and use of R statistical phenopix package to quantify plant phenology and phenophases in four plant communities in the semi-arid cold desert region of the Great Basin. We developed an automated variable snow/night filter for removing ephemeral snow events, which allowed fitting of phenophases with a double logistic algorithm. We were able to detect low amplitude seasonal variation in pinyon and juniper canopies and sagebrush steppe, and characterize wet and mesic meadows in area-averaged analyses. We used individual pixel-based spatial analyses to separate sagebrush shrub canopy pixels from interspace by determining differences in phenophases of sagebrush relative to interspace. The ability to monitor plant phenology with camera-based images fills spatial and temporal gaps in remotely sensed data and field based surveys, allowing species level relationships between environmental variables and phenology to be developed on a fine time scale thus providing powerful new tools for land management. Full article

(This article belongs to the Section Remote Sensors)

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15 pages, 5973 KiB

Open AccessArticle

Sensor for In-Motion Continuous 3D Shape Measurement Based on Dual Line-Scan Cameras

by Bo Sun, Jigui Zhu, Linghui Yang^*

, Shourui Yang and Yin Guo

State Key Laboratory of Precision Measuring Technology and Instruments, Tianjin University, Tianjin 300072, China

Sensors 2016, 16(11), 1949; https://doi.org/10.3390/s16111949 - 18 Nov 2016

Cited by 41 | Viewed by 7585

Abstract

The acquisition of three-dimensional surface data plays an increasingly important role in the industrial sector. Numerous 3D shape measurement techniques have been developed. However, there are still limitations and challenges in fast measurement of large-scale objects or high-speed moving objects. The innovative line [...] Read more.

The acquisition of three-dimensional surface data plays an increasingly important role in the industrial sector. Numerous 3D shape measurement techniques have been developed. However, there are still limitations and challenges in fast measurement of large-scale objects or high-speed moving objects. The innovative line scan technology opens up new potentialities owing to the ultra-high resolution and line rate. To this end, a sensor for in-motion continuous 3D shape measurement based on dual line-scan cameras is presented. In this paper, the principle and structure of the sensor are investigated. The image matching strategy is addressed and the matching error is analyzed. The sensor has been verified by experiments and high-quality results are obtained. Full article

(This article belongs to the Section Physical Sensors)

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21 pages, 9242 KiB

Open AccessArticle

Performance Evaluation of Proximal Sensors for Soil Assessment in Smallholder Farms in Embu County, Kenya

by Kristin Piikki^1,2,*

, Mats Söderström^1,2

, Jan Eriksson³, Jamleck Muturi John⁴, Patrick Ireri Muthee⁵, Johanna Wetterlind² and Eric Lund⁶

¹ Regional Office for Africa, International Center for Tropical Agriculture (CIAT), Kasarani Rd., ICIPE Complex, P.O. Box 823-00621, Nairobi, Kenya

² Department of Soil and Environment, Precision Agriculture and Pedometrics, Swedish University of Agricultural Sciences (SLU), Box 234, SE-53223 Skara, Sweden

³ Department of Soil and Environment, Biogeochemistry, Swedish University of Agricultural Sciences (SLU), Box 7014, SE-75007 Uppsala, Sweden

⁴ School of Agriculture, University of Embu (UoEm), P.O. Box 6-60100, Embu, Kenya

⁵ Ministry of Agriculture, Embu, Kenya

⁶ Veris Technologies Inc., 1925 Clay Ridge Ct., Salina, KS 67401, USA

Sensors 2016, 16(11), 1950; https://doi.org/10.3390/s16111950 - 19 Nov 2016

Cited by 26 | Viewed by 11709

Abstract

Four proximal soil sensors were tested at four smallholder farms in Embu County, Kenya: a portable X-ray fluorescence sensor (PXRF), a mobile phone application for soil color determination by photography, a dual-depth electromagnetic induction (EMI) sensor, and a LED-based soil optical reflectance sensor. [...] Read more.

Four proximal soil sensors were tested at four smallholder farms in Embu County, Kenya: a portable X-ray fluorescence sensor (PXRF), a mobile phone application for soil color determination by photography, a dual-depth electromagnetic induction (EMI) sensor, and a LED-based soil optical reflectance sensor. Measurements were made at 32–43 locations at each site. Topsoil samples were analyzed for plant-available nutrients (N, P, K, Mg, Ca, S, B, Mn, Zn, Cu, and Fe), pH, total nitrogen (TN) and total carbon (TC), soil texture, cation exchange capacity (CEC), and exchangeable aluminum (Al). Multivariate prediction models of each of the lab-analyzed soil properties were parameterized for 576 sensor-variable combinations. Prediction models for K, N, Ca and S, B, Zn, Mn, Fe, TC, Al, and CEC met the setup criteria for functional, robust, and accurate models. The PXRF sensor was the sensor most often included in successful models. We concluded that the combination of a PXRF and a portable soil reflectance sensor is a promising combination of handheld soil sensors for the development of in situ soil assessments as a field-based alternative or complement to laboratory measurements. Full article

(This article belongs to the Collection Sensors in Agriculture and Forestry)

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14 pages, 3457 KiB

Open AccessArticle

Localization of CO₂ Leakage from a Circular Hole on a Flat-Surface Structure Using a Circular Acoustic Emission Sensor Array

by Xiwang Cui^1,*, Yong Yan^1,2

, Miao Guo¹, Xiaojuan Han¹ and Yonghui Hu¹

¹ School of Control and Computer Engineering, North China Electric Power University, Beijing 102206, China

² School of Engineering and Digital Arts, University of Kent, Canterbury, Kent CT2 7NT, UK

Sensors 2016, 16(11), 1951; https://doi.org/10.3390/s16111951 - 19 Nov 2016

Cited by 18 | Viewed by 4705

Abstract

Leak localization is essential for the safety and maintenance of storage vessels. This study proposes a novel circular acoustic emission sensor array to realize the continuous CO₂ leak localization from a circular hole on the surface of a large storage vessel in [...] Read more.

Leak localization is essential for the safety and maintenance of storage vessels. This study proposes a novel circular acoustic emission sensor array to realize the continuous CO₂ leak localization from a circular hole on the surface of a large storage vessel in a carbon capture and storage system. Advantages of the proposed array are analyzed and compared with the common sparse arrays. Experiments were carried out on a laboratory-scale stainless steel plate and leak signals were obtained from a circular hole in the center of this flat-surface structure. In order to reduce the influence of the ambient noise and dispersion of the acoustic wave on the localization accuracy, ensemble empirical mode decomposition is deployed to extract the useful leak signal. The time differences between the signals from the adjacent sensors in the array are calculated through correlation signal processing before estimating the corresponding distance differences between the sensors. A hyperbolic positioning algorithm is used to identify the location of the circular leak hole. Results show that the circular sensor array has very good directivity toward the circular leak hole. Furthermore, an optimized method is proposed by changing the position of the circular sensor array on the flat-surface structure or adding another circular sensor array to identify the direction of the circular leak hole. Experiential results obtained on a 100 cm × 100 cm stainless steel plate demonstrate that the full-scale error in the leak localization is within 0.6%. Full article

(This article belongs to the Section Physical Sensors)

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24 pages, 22651 KiB

Open AccessArticle

Towards Camera-LIDAR Fusion-Based Terrain Modelling for Planetary Surfaces: Review and Analysis

by Affan Shaukat, Peter C. Blacker, Conrad Spiteri and Yang Gao^*

Surrey Space Centre, Faculty of Engineering and Physical Sciences, University of Surrey, Guildford GU2 7XH, UK

Sensors 2016, 16(11), 1952; https://doi.org/10.3390/s16111952 - 20 Nov 2016

Cited by 30 | Viewed by 13180

Abstract

In recent decades, terrain modelling and reconstruction techniques have increased research interest in precise short and long distance autonomous navigation, localisation and mapping within field robotics. One of the most challenging applications is in relation to autonomous planetary exploration using mobile robots. Rovers [...] Read more.

In recent decades, terrain modelling and reconstruction techniques have increased research interest in precise short and long distance autonomous navigation, localisation and mapping within field robotics. One of the most challenging applications is in relation to autonomous planetary exploration using mobile robots. Rovers deployed to explore extraterrestrial surfaces are required to perceive and model the environment with little or no intervention from the ground station. Up to date, stereopsis represents the state-of-the art method and can achieve short-distance planetary surface modelling. However, future space missions will require scene reconstruction at greater distance, fidelity and feature complexity, potentially using other sensors like Light Detection And Ranging (LIDAR). LIDAR has been extensively exploited for target detection, identification, and depth estimation in terrestrial robotics, but is still under development to become a viable technology for space robotics. This paper will first review current methods for scene reconstruction and terrain modelling using cameras in planetary robotics and LIDARs in terrestrial robotics; then we will propose camera-LIDAR fusion as a feasible technique to overcome the limitations of either of these individual sensors for planetary exploration. A comprehensive analysis will be presented to demonstrate the advantages of camera-LIDAR fusion in terms of range, fidelity, accuracy and computation. Full article

(This article belongs to the Special Issue Vision-Based Sensors in Field Robotics)

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22 pages, 7492 KiB

Open AccessArticle

Smart Toys Designed for Detecting Developmental Delays

by Diego Rivera¹

, Antonio García¹, Bernardo Alarcos¹

, Juan R. Velasco^1,*

, José Eugenio Ortega² and Isaías Martínez-Yelmo¹

¹ Departamento de Automática, Escuela Politécnica Superior, Universidad de Alcalá. Campus Universitario, 28871 Alcalá de Henares, Madrid, Spain

² Facultad de Psicología, Departamento de Psicología Biológica y de la Salud, Universidad Autónoma de Madrid, Calle Iván Pavlov, 6, 28049 Madrid, Spain

Sensors 2016, 16(11), 1953; https://doi.org/10.3390/s16111953 - 20 Nov 2016

Cited by 18 | Viewed by 12503

Abstract

In this paper, we describe the design considerations and implementation of a smart toy system, a technology for supporting the automatic recording and analysis for detecting developmental delays recognition when children play using the smart toy. To achieve this goal, we take advantage [...] Read more.

In this paper, we describe the design considerations and implementation of a smart toy system, a technology for supporting the automatic recording and analysis for detecting developmental delays recognition when children play using the smart toy. To achieve this goal, we take advantage of the current commercial sensor features (reliability, low consumption, easy integration, etc.) to develop a series of sensor-based low-cost devices. Specifically, our prototype system consists of a tower of cubes augmented with wireless sensing capabilities and a mobile computing platform that collect the information sent from the cubes allowing the later analysis by childhood development professionals in order to verify a normal behaviour or to detect a potential disorder. This paper presents the requirements of the toy and discusses our choices in toy design, technology used, selected sensors, process to gather data from the sensors and generate information that will help in the decision-making and communication of the information to the collector system. In addition, we also describe the play activities the system supports. Full article

(This article belongs to the Special Issue Sensing Technology for Healthcare System)

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20 pages, 18233 KiB

Open AccessArticle

Expanding the Detection of Traversable Area with RealSense for the Visually Impaired

by Kailun Yang, Kaiwei Wang^*, Weijian Hu and Jian Bai

College of Optical Science and Engineering, Zhejiang University, Hangzhou 310027, China

Sensors 2016, 16(11), 1954; https://doi.org/10.3390/s16111954 - 21 Nov 2016

Cited by 80 | Viewed by 13831

Abstract

The introduction of RGB-Depth (RGB-D) sensors into the visually impaired people (VIP)-assisting area has stirred great interest of many researchers. However, the detection range of RGB-D sensors is limited by narrow depth field angle and sparse depth map in the distance, which hampers [...] Read more.

The introduction of RGB-Depth (RGB-D) sensors into the visually impaired people (VIP)-assisting area has stirred great interest of many researchers. However, the detection range of RGB-D sensors is limited by narrow depth field angle and sparse depth map in the distance, which hampers broader and longer traversability awareness. This paper proposes an effective approach to expand the detection of traversable area based on a RGB-D sensor, the Intel RealSense R200, which is compatible with both indoor and outdoor environments. The depth image of RealSense is enhanced with IR image large-scale matching and RGB image-guided filtering. Traversable area is obtained with RANdom SAmple Consensus (RANSAC) segmentation and surface normal vector estimation, preliminarily. A seeded growing region algorithm, combining the depth image and RGB image, enlarges the preliminary traversable area greatly. This is critical not only for avoiding close obstacles, but also for allowing superior path planning on navigation. The proposed approach has been tested on a score of indoor and outdoor scenarios. Moreover, the approach has been integrated into an assistance system, which consists of a wearable prototype and an audio interface. Furthermore, the presented approach has been proved to be useful and reliable by a field test with eight visually impaired volunteers. Full article

(This article belongs to the Special Issue Imaging: Sensors and Technologies)

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27 pages, 2450 KiB

Open AccessArticle

An Improved Mobility-Based Control Protocol for Tolerating Clone Failures in Wireless Sensor Networks

by Yuping Zhou^1,*, Naixue Xiong², Mingxin Tan³, Rufeng Huang¹ and Jon Kleonbet⁴

¹ Department of Computer Science, Minnan Normal University, Zhangzhou 363000, China

² Department of Computer Science, Georgia State University, Atlanta, GA 30302, USA

³ College of Physical Science and Technology, Central China Normal University, Wuhan 430079, China

⁴ College of Engineering, Cornell University, Ithaca, NY 14850, USA

Sensors 2016, 16(11), 1955; https://doi.org/10.3390/s16111955 - 23 Nov 2016

Cited by 3 | Viewed by 4775

Abstract

Nowadays, with the ubiquitous presence of the Internet of Things industry, the application of emerging sensor networks has become a focus of public attention. Unattended sensor nodes can be comprised and cloned to destroy the network topology. This paper proposes a novel distributed [...] Read more.

Nowadays, with the ubiquitous presence of the Internet of Things industry, the application of emerging sensor networks has become a focus of public attention. Unattended sensor nodes can be comprised and cloned to destroy the network topology. This paper proposes a novel distributed protocol and management technique for the detection of mobile replicas to tolerate node failures. In our scheme, sensors’ location claims are forwarded to obtain samples only when the corresponding witnesses meet. Meanwhile, sequential tests of statistical hypotheses are applied to further detect the cloned node by witnesses. The combination of randomized detection based on encountering and sequential tests drastically reduces the routing overhead and false positive/negative rate for detection. Theoretical analysis and simulation results show the detection efficiency and reasonable overhead of the proposed method. Full article

(This article belongs to the Special Issue Topology Control in Emerging Sensor Networks)

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22 pages, 5694 KiB

Open AccessArticle

Probabilistic Model Updating for Sizing of Hole-Edge Crack Using Fiber Bragg Grating Sensors and the High-Order Extended Finite Element Method

by Jingjing He^1,2, Jinsong Yang¹, Yongxiang Wang^2,*

, Haim Waisman² and Weifang Zhang¹

¹ School of Reliability and System Engineering, Beihang University, Weimin Building, No. 37, Xueyuan Road, Haidian District, Beijing 100191, China

² Department of Civil Engineering & Engineering Mechanics, Columbia University, New York, NY 10027, USA

Sensors 2016, 16(11), 1956; https://doi.org/10.3390/s16111956 - 21 Nov 2016

Cited by 28 | Viewed by 7419

Abstract

This paper presents a novel framework for probabilistic crack size quantification using fiber Bragg grating (FBG) sensors. The key idea is to use a high-order extended finite element method (XFEM) together with a transfer (T)-matrix method to analyze the reflection intensity spectra of [...] Read more.

This paper presents a novel framework for probabilistic crack size quantification using fiber Bragg grating (FBG) sensors. The key idea is to use a high-order extended finite element method (XFEM) together with a transfer (T)-matrix method to analyze the reflection intensity spectra of FBG sensors, for various crack sizes. Compared with the standard FEM, the XFEM offers two superior capabilities: (i) a more accurate representation of fields in the vicinity of the crack tip singularity and (ii) alleviation of the need for costly re-meshing as the crack size changes. Apart from the classical four-term asymptotic enrichment functions in XFEM, we also propose to incorporate higher-order functions, aiming to further improve the accuracy of strain fields upon which the reflection intensity spectra are based. The wavelength of the reflection intensity spectra is extracted as a damage sensitive quantity, and a baseline model with five parameters is established to quantify its correlation with the crack size. In order to test the feasibility of the predictive model, we design FBG sensor-based experiments to detect fatigue crack growth in structures. Furthermore, a Bayesian method is proposed to update the parameters of the baseline model using only a few available experimental data points (wavelength versus crack size) measured by one of the FBG sensors and an optical microscope, respectively. Given the remaining data points of wavelengths, even measured by FBG sensors at different positions, the updated model is shown to give crack size predictions that match well with the experimental observations. Full article

(This article belongs to the Special Issue Optical Fiber Sensors 2016)

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21 pages, 10902 KiB

Open AccessArticle

Bamboo Classification Using WorldView-2 Imagery of Giant Panda Habitat in a Large Shaded Area in Wolong, Sichuan Province, China

by Yunwei Tang^1,*

, Linhai Jing^1,*, Hui Li¹

, Qingjie Liu¹, Qi Yan¹ and Xiuxia Li²

¹ Key Laboratory of Digital Earth Sciences, Institute of Remote Sensing and Digital Earth, Chinese Academy of Sciences, No. 9 Dengzhuang South Road, Beijing 100094, China

² School of Geography, Beijing Normal University, No. 19 Xinjiekou Wai Street, Beijing 100875, China

Sensors 2016, 16(11), 1957; https://doi.org/10.3390/s16111957 - 22 Nov 2016

Cited by 14 | Viewed by 7920

Abstract

This study explores the ability of WorldView-2 (WV-2) imagery for bamboo mapping in a mountainous region in Sichuan Province, China. A large area of this place is covered by shadows in the image, and only a few sampled points derived were useful. In [...] Read more.

This study explores the ability of WorldView-2 (WV-2) imagery for bamboo mapping in a mountainous region in Sichuan Province, China. A large area of this place is covered by shadows in the image, and only a few sampled points derived were useful. In order to identify bamboos based on sparse training data, the sample size was expanded according to the reflectance of multispectral bands selected using the principal component analysis (PCA). Then, class separability based on the training data was calculated using a feature space optimization method to select the features for classification. Four regular object-based classification methods were applied based on both sets of training data. The results show that the k-nearest neighbor (k-NN) method produced the greatest accuracy. A geostatistically-weighted k-NN classifier, accounting for the spatial correlation between classes, was then applied to further increase the accuracy. It achieved 82.65% and 93.10% of the producer’s and user’s accuracies respectively for the bamboo class. The canopy densities were estimated to explain the result. This study demonstrates that the WV-2 image can be used to identify small patches of understory bamboos given limited known samples, and the resulting bamboo distribution facilitates the assessments of the habitats of giant pandas. Full article

(This article belongs to the Section Remote Sensors)

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20 pages, 3562 KiB

Open AccessArticle

Queuing Time Prediction Using WiFi Positioning Data in an Indoor Scenario

by Hua Shu^1,2

, Ci Song¹, Tao Pei^1,*, Lianming Xu³, Yang Ou³, Libin Zhang⁴ and Tao Li⁴

¹ State Key Laboratory of Resources and Environmental Information System, Institute of Geographic Sciences and Natural Resources Research, CAS, Beijing 100101, China

² University of Chinese Academy of Sciences, Beijing 100049, China

³ RTmap Science and Technology Ltd., Beijing 100093, China

⁴ Information Technology Department, Beijing Capital International Airport Co., Ltd., Beijing 100621, China

Sensors 2016, 16(11), 1958; https://doi.org/10.3390/s16111958 - 22 Nov 2016

Cited by 21 | Viewed by 6216

Abstract

Queuing is common in urban public places. Automatically monitoring and predicting queuing time can not only help individuals to reduce their wait time and alleviate anxiety but also help managers to allocate resources more efficiently and enhance their ability to address emergencies. This [...] Read more.

Queuing is common in urban public places. Automatically monitoring and predicting queuing time can not only help individuals to reduce their wait time and alleviate anxiety but also help managers to allocate resources more efficiently and enhance their ability to address emergencies. This paper proposes a novel method to estimate and predict queuing time in indoor environments based on WiFi positioning data. First, we use a series of parameters to identify the trajectories that can be used as representatives of queuing time. Next, we divide the day into equal time slices and estimate individuals’ average queuing time during specific time slices. Finally, we build a nonstandard autoregressive (NAR) model trained using the previous day’s WiFi estimation results and actual queuing time to predict the queuing time in the upcoming time slice. A case study comparing two other time series analysis models shows that the NAR model has better precision. Random topological errors caused by the drift phenomenon of WiFi positioning technology (locations determined by a WiFi positioning system may drift accidently) and systematic topological errors caused by the positioning system are the main factors that affect the estimation precision. Therefore, we optimize the deployment strategy during the positioning system deployment phase and propose a drift ratio parameter pertaining to the trajectory screening phase to alleviate the impact of topological errors and improve estimates. The WiFi positioning data from an eight-day case study conducted at the T3-C entrance of Beijing Capital International Airport show that the mean absolute estimation error is 147 s, which is approximately 26.92% of the actual queuing time. For predictions using the NAR model, the proportion is approximately 27.49%. The theoretical predictions and the empirical case study indicate that the NAR model is an effective method to estimate and predict queuing time in indoor public areas. Full article

(This article belongs to the Section Physical Sensors)

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16 pages, 3495 KiB

Open AccessArticle

Evaluation of Hyaluronic Acid Dilutions at Different Concentrations Using a Quartz Crystal Resonator (QCR) for the Potential Diagnosis of Arthritic Diseases

by Luis Armando Carvajal Ahumada^1,2,3,4,*, Marco Xavier Rivera González^1,2, Oscar Leonardo Herrera Sandoval^3,4 and José Javier Serrano Olmedo^1,2

¹ Center for Biomedical Technology (CTB), Technical University of Madrid (UPM), 28040 Madrid, Spain

² Networking Research Center of Bioengineering, Biomaterials and Nanomedicine (CIBER-BBN), Technical University of Madrid (UPM), 28040 Madrid, Spain

³ Research and Technological Development Center of Electrical, Electronic and ICT Industry (CIDEI), 111311 Bogotá, Colombia

⁴ Faculty of Engineering and Basic Sciences, Central University, 111711 Bogotá, Colombia

Sensors 2016, 16(11), 1959; https://doi.org/10.3390/s16111959 - 22 Nov 2016

Cited by 12 | Viewed by 6087

Abstract

The main objective of this article is to demonstrate through experimental means the capacity of the quartz crystal resonator (QCR) to characterize biological samples of aqueous dilutions of hyaluronic acid according to their viscosity and how this capacity may be useful in the [...] Read more.

The main objective of this article is to demonstrate through experimental means the capacity of the quartz crystal resonator (QCR) to characterize biological samples of aqueous dilutions of hyaluronic acid according to their viscosity and how this capacity may be useful in the potential diagnosis of arthritic diseases. The synovial fluid is viscous due to the presence of hyaluronic acid, synthesized by synovial lining cells (type B), and secreted into the synovial fluid thus making the fluid viscous. In consequence, aqueous dilutions of hyaluronic acid may be used as samples to emulate the synovial fluid. Due to the viscoelastic and pseudo-plastic behavior of hyaluronic acid, it is necessary to use the Rouse model in order to obtain viscosity values comparable with viscometer measures. A Fungilab viscometer (rheometer) was used to obtain reference measures of the viscosity in each sample in order to compare them with the QCR prototype measures. Full article

(This article belongs to the Special Issue Point-of-Care Biosensors)

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21 pages, 1095 KiB

Open AccessArticle

IEEE 802.11ah: A Technology to Face the IoT Challenge

by Victor Baños-Gonzalez^1,*, M. Shahwaiz Afaqui², Elena Lopez-Aguilera¹ and Eduard Garcia-Villegas¹

¹ Department of Network Engineering, Universitat Politècnica de Catalunya BarcelonaTech, C/Esteve Terradas, 7, Castelldefels 08860, Spain

² Department of Electronics Engineering, Maynooth University, Maynooth, Kildare W23 F2H6, Ireland

Sensors 2016, 16(11), 1960; https://doi.org/10.3390/s16111960 - 22 Nov 2016

Cited by 89 | Viewed by 15508

Abstract

Since the conception of the Internet of things (IoT), a large number of promising applications and technologies have been developed, which will change different aspects in our daily life. This paper explores the key characteristics of the forthcoming IEEE 802.11ah specification. This future [...] Read more.

Since the conception of the Internet of things (IoT), a large number of promising applications and technologies have been developed, which will change different aspects in our daily life. This paper explores the key characteristics of the forthcoming IEEE 802.11ah specification. This future IEEE 802.11 standard aims to amend the IEEE 802.11 legacy specification to support IoT requirements. We present a thorough evaluation of the foregoing amendment in comparison to the most notable IEEE 802.11 standards. In addition, we expose the capabilities of future IEEE 802.11ah in supporting different IoT applications. Also, we provide a brief overview of the technology contenders that are competing to cover the IoT communications framework. Numerical results are presented showing how the future IEEE 802.11ah specification offers the features required by IoT communications, thus putting forward IEEE 802.11ah as a technology to cater the needs of the Internet of Things paradigm. Full article

(This article belongs to the Section Sensor Networks)

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21 pages, 2815 KiB

Open AccessArticle

Images from Bits: Non-Iterative Image Reconstruction for Quanta Image Sensors

by Stanley H. Chan^1,2,*, Omar A. Elgendy¹

and Xiran Wang¹

¹ School of Electrical and Computer Engineering, Purdue University, 465 Northwestern Ave, West Lafayette, IN 47907, USA

² Department of Statistics, Purdue University, 250 N. University Street, West Lafayette, IN 47907, USA

Sensors 2016, 16(11), 1961; https://doi.org/10.3390/s16111961 - 22 Nov 2016

Cited by 54 | Viewed by 12228

Abstract

A quanta image sensor (QIS) is a class of single-photon imaging devices that measure light intensity using oversampled binary observations. Because of the stochastic nature of the photon arrivals, data acquired by QIS is a massive stream of random binary bits. The goal [...] Read more.

A quanta image sensor (QIS) is a class of single-photon imaging devices that measure light intensity using oversampled binary observations. Because of the stochastic nature of the photon arrivals, data acquired by QIS is a massive stream of random binary bits. The goal of image reconstruction is to recover the underlying image from these bits. In this paper, we present a non-iterative image reconstruction algorithm for QIS. Unlike existing reconstruction methods that formulate the problem from an optimization perspective, the new algorithm directly recovers the images through a pair of nonlinear transformations and an off-the-shelf image denoising algorithm. By skipping the usual optimization procedure, we achieve orders of magnitude improvement in speed and even better image reconstruction quality. We validate the new algorithm on synthetic datasets, as well as real videos collected by one-bit single-photon avalanche diode (SPAD) cameras. Full article

(This article belongs to the Special Issue Photon-Counting Image Sensors)

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40 pages, 1455 KiB

Open AccessArticle

Automated Urban Travel Interpretation: A Bottom-up Approach for Trajectory Segmentation

by Rahul Deb Das^* and Stephan Winter

Department of Infrastructure Engineering, The University of Melbourne, Parkville 3010, Australia

Sensors 2016, 16(11), 1962; https://doi.org/10.3390/s16111962 - 23 Nov 2016

Cited by 23 | Viewed by 7923

Abstract

Understanding travel behavior is critical for an effective urban planning as well as for enabling various context-aware service provisions to support mobility as a service (MaaS). Both applications rely on the sensor traces generated by travellers’ smartphones. These traces can be used to [...] Read more.

Understanding travel behavior is critical for an effective urban planning as well as for enabling various context-aware service provisions to support mobility as a service (MaaS). Both applications rely on the sensor traces generated by travellers’ smartphones. These traces can be used to interpret travel modes, both for generating automated travel diaries as well as for real-time travel mode detection. Current approaches segment a trajectory by certain criteria, e.g., drop in speed. However, these criteria are heuristic, and, thus, existing approaches are subjective and involve significant vagueness and uncertainty in activity transitions in space and time. Also, segmentation approaches are not suited for real time interpretation of open-ended segments, and cannot cope with the frequent gaps in the location traces. In order to address all these challenges a novel, state based bottom-up approach is proposed. This approach assumes a fixed atomic segment of a homogeneous state, instead of an event-based segment, and a progressive iteration until a new state is found. The research investigates how an atomic state-based approach can be developed in such a way that can work in real time, near-real time and offline mode and in different environmental conditions with their varying quality of sensor traces. The results show the proposed bottom-up model outperforms the existing event-based segmentation models in terms of adaptivity, flexibility, accuracy and richness in information delivery pertinent to automated travel behavior interpretation. Full article

(This article belongs to the Section Physical Sensors)

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19 pages, 2632 KiB

Open AccessArticle

Accelerating Families of Fuzzy K-Means Algorithms for Vector Quantization Codebook Design

by Edson Mata¹, Silvio Bandeira¹, Paulo De Mattos Neto², Waslon Lopes^3,* and Francisco Madeiro¹

¹ Center of Science and Technology, Catholic University of Pernambuco (UNICAP), Recife 50050-900, Brazil

² Centro de Informática, Universidade Federal de Pernambuco (UFPE), Recife 50740-560, Brazil

³ Department of Electrical Engineering, Center of Alternative and Renewable Energy, Federal University of Paraíba (UFPB), João Pessoa 58038-130, Brazil

Sensors 2016, 16(11), 1963; https://doi.org/10.3390/s16111963 - 23 Nov 2016

Cited by 5 | Viewed by 4841

Abstract

The performance of signal processing systems based on vector quantization depends on codebook design. In the image compression scenario, the quality of the reconstructed images depends on the codebooks used. In this paper, alternatives are proposed for accelerating families of fuzzy K-means algorithms [...] Read more.

The performance of signal processing systems based on vector quantization depends on codebook design. In the image compression scenario, the quality of the reconstructed images depends on the codebooks used. In this paper, alternatives are proposed for accelerating families of fuzzy K-means algorithms for codebook design. The acceleration is obtained by reducing the number of iterations of the algorithms and applying efficient nearest neighbor search techniques. Simulation results concerning image vector quantization have shown that the acceleration obtained so far does not decrease the quality of the reconstructed images. Codebook design time savings up to about 40% are obtained by the accelerated versions with respect to the original versions of the algorithms. Full article

(This article belongs to the Section Physical Sensors)

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18 pages, 1595 KiB

Open AccessArticle

Multi-Target Tracking Using an Improved Gaussian Mixture CPHD Filter

by Weijian Si, Liwei Wang and Zhiyu Qu^*

College of Information and Communication Engineering, Harbin Engineering University, Harbin 150001, China

Sensors 2016, 16(11), 1964; https://doi.org/10.3390/s16111964 - 23 Nov 2016

Cited by 15 | Viewed by 4857

Abstract

The cardinalized probability hypothesis density (CPHD) filter is an alternative approximation to the full multi-target Bayesian filter for tracking multiple targets. However, although the joint propagation of the posterior intensity and cardinality distribution in its recursion allows more reliable estimates of the target [...] Read more.

The cardinalized probability hypothesis density (CPHD) filter is an alternative approximation to the full multi-target Bayesian filter for tracking multiple targets. However, although the joint propagation of the posterior intensity and cardinality distribution in its recursion allows more reliable estimates of the target number than the PHD filter, the CPHD filter suffers from the spooky effect where there exists arbitrary PHD mass shifting in the presence of missed detections. To address this issue in the Gaussian mixture (GM) implementation of the CPHD filter, this paper presents an improved GM-CPHD filter, which incorporates a weight redistribution scheme into the filtering process to modify the updated weights of the Gaussian components when missed detections occur. In addition, an efficient gating strategy that can adaptively adjust the gate sizes according to the number of missed detections of each Gaussian component is also presented to further improve the computational efficiency of the proposed filter. Simulation results demonstrate that the proposed method offers favorable performance in terms of both estimation accuracy and robustness to clutter and detection uncertainty over the existing methods. Full article

(This article belongs to the Section Physical Sensors)

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21 pages, 5341 KiB

Open AccessArticle

A Real-Time Kinect Signature-Based Patient Home Monitoring System

by Gaddi Blumrosen^1,*,†, Yael Miron², Nathan Intrator^1,3 and Meir Plotnik^2,3,4

¹ Blavatnik School of Computer Science, Tel Aviv University, Tel Aviv 69978, Israel

² Center of Advanced Technologies in Rehabilitation, Sheba Medical Center, Ramat Gan 52621, Israel

³ Sagol School of Neuroscience, Tel Aviv University, Tel Aviv 6997801, Israel

⁴ Department of Physiology and Pharmacology, Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv 6997801, Israel

^† Current affiliation: Multiscale Systems Biology and Modeling Group, IBM T.J. Watson Research Center, Yorktown Heights 10598, NY, USA.

Sensors 2016, 16(11), 1965; https://doi.org/10.3390/s16111965 - 23 Nov 2016

Cited by 34 | Viewed by 8207

Abstract

Assessment of body kinematics during performance of daily life activities at home plays a significant role in medical condition monitoring of elderly people and patients with neurological disorders. The affordable and non-wearable Microsoft Kinect (“Kinect”) system has been recently used to estimate human [...] Read more.

Assessment of body kinematics during performance of daily life activities at home plays a significant role in medical condition monitoring of elderly people and patients with neurological disorders. The affordable and non-wearable Microsoft Kinect (“Kinect”) system has been recently used to estimate human subject kinematic features. However, the Kinect suffers from a limited range and angular coverage, distortion in skeleton joints’ estimations, and erroneous multiplexing of different subjects’ estimations to one. This study addresses these limitations by incorporating a set of features that create a unique “Kinect Signature”. The Kinect Signature enables identification of different subjects in the scene, automatically assign the kinematics feature estimations only to the subject of interest, and provide information about the quality of the Kinect-based estimations. The methods were verified by a set of experiments, which utilize real-time scenarios commonly used to assess motor functions in elderly subjects and in subjects with neurological disorders. The experiment results indicate that the skeleton based Kinect Signature features can be used to identify different subjects in high accuracy. We demonstrate how these capabilities can be used to assign the Kinect estimations to the Subject of Interest, and exclude low quality tracking features. The results of this work can help in establishing reliable kinematic features, which can assist in future to obtain objective scores for medical analysis of patient condition at home while not restricted to perform daily life activities. Full article

(This article belongs to the Special Issue Sensing Technology for Healthcare System)

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14 pages, 1185 KiB

Open AccessArticle

Effects of Sampling Conditions and Environmental Factors on Fecal Volatile Organic Compound Analysis by an Electronic Nose Device

by Daniel J. C. Berkhout^1,2,*

, Marc A. Benninga¹, Ruby M. Van Stein²

, Paul Brinkman³, Hendrik J. Niemarkt⁴

, Nanne K. H. De Boer⁵ and Tim G. J. De Meij²

¹ Department of Pediatric Gastroenterology, Emma Children’s Hospital/Academic Medical Center, Meibergdreef 9, 1105 AZ Amsterdam, The Netherlands

² Department of Pediatric Gastroenterology, VU University Medical Center, De Boelelaan 1117, 1081 HV Amsterdam, The Netherlands

³ Department of Respiratory Medicine, Academic Medical Center, Meibergdreef 9, 1105 AZ Amsterdam, The Netherlands

⁴ Neonatal Intensive Care Unit, Máxima Medical Center, De Run 4600, 5504 DB Veldhoven, The Netherlands

⁵ Department of Gastroenterology and Hepatology, VU University Medical Center, De Boelelaan 1117, 1081 HV Amsterdam, The Netherlands

Sensors 2016, 16(11), 1967; https://doi.org/10.3390/s16111967 - 23 Nov 2016

Cited by 33 | Viewed by 6664

Abstract

Prior to implementation of volatile organic compound (VOC) analysis in clinical practice, substantial challenges, including methodological, biological and analytical difficulties are faced. The aim of this study was to evaluate the influence of several sampling conditions and environmental factors on fecal VOC profiles, [...] Read more.

Prior to implementation of volatile organic compound (VOC) analysis in clinical practice, substantial challenges, including methodological, biological and analytical difficulties are faced. The aim of this study was to evaluate the influence of several sampling conditions and environmental factors on fecal VOC profiles, analyzed by an electronic nose (eNose). Effects of fecal sample mass, water content, duration of storage at room temperature, fecal sample temperature, number of freeze–thaw cycles and effect of sampling method (rectal swabs vs. fecal samples) on VOC profiles were assessed by analysis of totally 725 fecal samples by means of an eNose (Cyranose320^®). Furthermore, fecal VOC profiles of totally 1285 fecal samples from 71 infants born at three different hospitals were compared to assess the influence of center of origin on VOC outcome. We observed that all analyzed variables significantly influenced fecal VOC composition. It was feasible to capture a VOC profile using rectal swabs, although this differed significantly from fecal VOC profiles of similar subjects. In addition, 1285 fecal VOC-profiles could significantly be discriminated based on center of birth. In conclusion, standardization of methodology is necessary before fecal VOC analysis can live up to its potential as diagnostic tool in clinical practice. Full article

(This article belongs to the Special Issue Gas Sensors for Health Care and Medical Applications)

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38 pages, 1438 KiB

Open AccessReview

State of the Art, Trends and Future of Bluetooth Low Energy, Near Field Communication and Visible Light Communication in the Development of Smart Cities

by Gonzalo Cerruela García^*, Irene Luque Ruiz

and Miguel Ángel Gómez-Nieto

Department of Computing and Numerical Analysis, University of Córdoba, 14071 Córdoba, Spain

Sensors 2016, 16(11), 1968; https://doi.org/10.3390/s16111968 - 23 Nov 2016

Cited by 65 | Viewed by 15859

Abstract

The current social impact of new technologies has produced major changes in all areas of society, creating the concept of a smart city supported by an electronic infrastructure, telecommunications and information technology. This paper presents a review of Bluetooth Low Energy (BLE), Near [...] Read more.

The current social impact of new technologies has produced major changes in all areas of society, creating the concept of a smart city supported by an electronic infrastructure, telecommunications and information technology. This paper presents a review of Bluetooth Low Energy (BLE), Near Field Communication (NFC) and Visible Light Communication (VLC) and their use and influence within different areas of the development of the smart city. The document also presents a review of Big Data Solutions for the management of information and the extraction of knowledge in an environment where things are connected by an “Internet of Things” (IoT) network. Lastly, we present how these technologies can be combined together to benefit the development of the smart city. Full article

(This article belongs to the Special Issue Smart City: Vision and Reality)

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14 pages, 7101 KiB

Open AccessArticle

Three-Dimensional Object Recognition and Registration for Robotic Grasping Systems Using a Modified Viewpoint Feature Histogram

by Chin-Sheng Chen¹

, Po-Chun Chen¹ and Chih-Ming Hsu^2,*

¹ Graduate Institute of Automation Technology, National Taipei University of Technology, Taipei 106, Taiwan

² Department of Mechanical Engineering, National Taipei University of Technology, Taipei 106, Taiwan

Sensors 2016, 16(11), 1969; https://doi.org/10.3390/s16111969 - 23 Nov 2016

Cited by 24 | Viewed by 8412

Abstract

This paper presents a novel 3D feature descriptor for object recognition and to identify poses when there are six-degrees-of-freedom for mobile manipulation and grasping applications. Firstly, a Microsoft Kinect sensor is used to capture 3D point cloud data. A viewpoint feature histogram (VFH) [...] Read more.

This paper presents a novel 3D feature descriptor for object recognition and to identify poses when there are six-degrees-of-freedom for mobile manipulation and grasping applications. Firstly, a Microsoft Kinect sensor is used to capture 3D point cloud data. A viewpoint feature histogram (VFH) descriptor for the 3D point cloud data then encodes the geometry and viewpoint, so an object can be simultaneously recognized and registered in a stable pose and the information is stored in a database. The VFH is robust to a large degree of surface noise and missing depth information so it is reliable for stereo data. However, the pose estimation for an object fails when the object is placed symmetrically to the viewpoint. To overcome this problem, this study proposes a modified viewpoint feature histogram (MVFH) descriptor that consists of two parts: a surface shape component that comprises an extended fast point feature histogram and an extended viewpoint direction component. The MVFH descriptor characterizes an object’s pose and enhances the system’s ability to identify objects with mirrored poses. Finally, the refined pose is further estimated using an iterative closest point when the object has been recognized and the pose roughly estimated by the MVFH descriptor and it has been registered on a database. The estimation results demonstrate that the MVFH feature descriptor allows more accurate pose estimation. The experiments also show that the proposed method can be applied in vision-guided robotic grasping systems. Full article

(This article belongs to the Special Issue Applications of Advanced Materials on Microelectronic and Optical Sensors)

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10 pages, 2389 KiB

Open AccessArticle

A Laminar Flow-Based Microfluidic Tesla Pump via Lithography Enabled 3D Printing

by Mohammed-Baker Habhab, Tania Ismail and Joe Fujiou Lo^*

Department of Mechanical Engineering, Bioengineering Program, University of Michigan at Dearborn, 2088 IAVS Building, 4901 Evergreen Rd., Dearborn, MI 48128, USA

Sensors 2016, 16(11), 1970; https://doi.org/10.3390/s16111970 - 23 Nov 2016

Cited by 30 | Viewed by 12957

Abstract

Tesla turbine and its applications in power generation and fluid flow were demonstrated by Nicholas Tesla in 1913. However, its real-world implementations were limited by the difficulty to maintain laminar flow between rotor disks, transient efficiencies during rotor acceleration, and the lack of [...] Read more.

Tesla turbine and its applications in power generation and fluid flow were demonstrated by Nicholas Tesla in 1913. However, its real-world implementations were limited by the difficulty to maintain laminar flow between rotor disks, transient efficiencies during rotor acceleration, and the lack of other applications that fully utilize the continuous flow outputs. All of the aforementioned limits of Tesla turbines can be addressed by scaling to the microfluidic flow regime. Demonstrated here is a microscale Tesla pump designed and fabricated using a Digital Light Processing (DLP) based 3D printer with 43 µm lateral and 30 µm thickness resolutions. The miniaturized pump is characterized by low Reynolds number of 1000 and a flow rate of up to 12.6 mL/min at 1200 rpm, unloaded. It is capable of driving a mixer network to generate microfluidic gradient. The continuous, laminar flow from Tesla turbines is well-suited to the needs of flow-sensitive microfluidics, where the integrated pump will enable numerous compact lab-on-a-chip applications. Full article

(This article belongs to the Special Issue Microfluidics-Based Microsystem Integration Research)

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27 pages, 6661 KiB

Open AccessArticle

Co-Creating the Cities of the Future

by Verónica Gutiérrez¹, Evangelos Theodoridis², Georgios Mylonas³

, Fengrui Shi⁴, Usman Adeel², Luis Diez¹

, Dimitrios Amaxilatis³, Johnny Choque¹, Guillem Camprodom⁵, Julie McCann⁴ and Luis Muñoz^1,*

¹ Communications Department, University of Cantabria, Santander 39005, Spain

² INTEL Labs Europe, London SW7 2AZ, UK

³ Computer Technology Institute and Press, “Diophantus”, Patras 26504, Greece

⁴ Department Computing, Imperial College London, London SW7 2AZ, UK

⁵ Institute for Advanced Architecture of Catalonia (IAAC), Barcelona 08005, Spain

Sensors 2016, 16(11), 1971; https://doi.org/10.3390/s16111971 - 23 Nov 2016

Cited by 41 | Viewed by 9935

Abstract

In recent years, the evolution of urban environments, jointly with the progress of the Information and Communication sector, have enabled the rapid adoption of new solutions that contribute to the growth in popularity of Smart Cities. Currently, the majority of the world population [...] Read more.

In recent years, the evolution of urban environments, jointly with the progress of the Information and Communication sector, have enabled the rapid adoption of new solutions that contribute to the growth in popularity of Smart Cities. Currently, the majority of the world population lives in cities encouraging different stakeholders within these innovative ecosystems to seek new solutions guaranteeing the sustainability and efficiency of such complex environments. In this work, it is discussed how the experimentation with IoT technologies and other data sources form the cities can be utilized to co-create in the OrganiCity project, where key actors like citizens, researchers and other stakeholders shape smart city services and applications in a collaborative fashion. Furthermore, a novel architecture is proposed that enables this organic growth of the future cities, facilitating the experimentation that tailors the adoption of new technologies and services for a better quality of life, as well as agile and dynamic mechanisms for managing cities. In this work, the different components and enablers of the OrganiCity platform are presented and discussed in detail and include, among others, a portal to manage the experiment life cycle, an Urban Data Observatory to explore data assets, and an annotations component to indicate quality of data, with a particular focus on the city-scale opportunistic data collection service operating as an alternative to traditional communications. Full article

(This article belongs to the Special Issue Smart City: Vision and Reality)

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14 pages, 2065 KiB

Open AccessArticle

Identification-While-Scanning of a Multi-Aircraft Formation Based on Sparse Recovery for Narrowband Radar

by Yuan Jiang¹, Jia Xu^1,*

, Shi-Bao Peng², Er-Ke Mao¹, Teng Long¹ and Ying-Ning Peng²

¹ School of Information and Electronics, Beijing Institute of Technology, Beijing 100081, China

² Department of Electronic Engineering, Tsinghua University, Beijing 100084, China

Sensors 2016, 16(11), 1972; https://doi.org/10.3390/s16111972 - 23 Nov 2016

Cited by 3 | Viewed by 5317

Abstract

It is known that the identification performance of a multi-aircraft formation (MAF) of narrowband radar mainly depends on the time on target (TOT). To realize the identification task in one rotated scan with limited TOT, the paper proposes a novel identification-while-scanning (IWS) method [...] Read more.

It is known that the identification performance of a multi-aircraft formation (MAF) of narrowband radar mainly depends on the time on target (TOT). To realize the identification task in one rotated scan with limited TOT, the paper proposes a novel identification-while-scanning (IWS) method based on sparse recovery to maintain high rotating speed and super-resolution for MAF identification, simultaneously. First, a multiple chirp signal model is established for MAF in a single scan, where different aircraft may have different Doppler centers and Doppler rates. Second, based on the sparsity of MAF in the Doppler parameter space, a novel hierarchical basis pursuit (HBP) method is proposed to obtain satisfactory sparse recovery performance as well as high computational efficiency. Furthermore, the parameter estimation performance of the proposed IWS identification method is analyzed with respect to recovery condition, signal-to-noise ratio and TOT. It is shown that an MAF can be effectively identified via HBP with a TOT of only about one hundred microseconds for IWS applications. Finally, some numerical experiment results are provided to demonstrate the effectiveness of the proposed method based on both simulated and real measured data. Full article

(This article belongs to the Special Issue Non-Contact Sensing)

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7 pages, 3093 KiB

Open AccessArticle

Design of Fresnel Lens-Type Multi-Trapping Acoustic Tweezers

by You-Lin Tu, Shih-Jui Chen^* and Yean-Ren Hwang

Department of Mechanical Engineering, National Central University, Taoyuan 32001, Taiwan

Sensors 2016, 16(11), 1973; https://doi.org/10.3390/s16111973 - 23 Nov 2016

Cited by 13 | Viewed by 8566

Abstract

In this paper, acoustic tweezers which use beam forming performed by a Fresnel zone plate are proposed. The performance has been demonstrated by finite element analysis, including the acoustic intensity, acoustic pressure, acoustic potential energy, gradient force, and particle distribution. The acoustic tweezers [...] Read more.

In this paper, acoustic tweezers which use beam forming performed by a Fresnel zone plate are proposed. The performance has been demonstrated by finite element analysis, including the acoustic intensity, acoustic pressure, acoustic potential energy, gradient force, and particle distribution. The acoustic tweezers use an ultrasound beam produced by a lead zirconate titanate (PZT) transducer operating at 2.4 MHz and 100 V_peak-to-peak in a water medium. The design of the Fresnel lens (zone plate) is based on air reflection, acoustic impedance matching, and the Fresnel half-wave band (FHWB) theory. This acoustic Fresnel lens can produce gradient force and acoustic potential wells that allow the capture and manipulation of single particles or clusters of particles. Simulation results strongly indicate a good trapping ability, for particles under 150 µm in diameter, in the minimum energy location. This can be useful for cell or microorganism manipulation. Full article

(This article belongs to the Section Physical Sensors)

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10 pages, 2723 KiB

Open AccessArticle

Molecularly Imprinted Filtering Adsorbents for Odor Sensing

by Sho Shinohara¹, You Chiyomaru², Fumihiro Sassa², Chuanjun Liu^2,3 and Kenshi Hayashi^2,*

¹ Graduate School of Systems Life Sciences, Kyushu University, 744 Motooka, Nishi-ku, Fukuoka 819-0395, Japan

² Graduate School of Information Science and Electrical Engineering, 744 Motooka, Nishi-ku, Fukuoka 819-0395, Japan

³ Research Laboratory, U.S.E Co. Ltd., 1-10-4 Hiroo, Shibuya-ku, Tokyo 150-0012, Japan

Sensors 2016, 16(11), 1974; https://doi.org/10.3390/s16111974 - 23 Nov 2016

Cited by 7 | Viewed by 6885

Abstract

Versatile odor sensors that can discriminate among huge numbers of environmental odorants are desired in many fields, including robotics, environmental monitoring, and food production. However, odor sensors comparable to an animal’s nose have not yet been developed. An animal’s olfactory system recognizes odor [...] Read more.

Versatile odor sensors that can discriminate among huge numbers of environmental odorants are desired in many fields, including robotics, environmental monitoring, and food production. However, odor sensors comparable to an animal’s nose have not yet been developed. An animal’s olfactory system recognizes odor clusters with specific molecular properties and uses this combinatorial information in odor discrimination. This suggests that measurement and clustering of odor molecular properties (e.g., polarity, size) using an artificial sensor is a promising approach to odor sensing. Here, adsorbents composed of composite materials with molecular recognition properties were developed for odor sensing. The selectivity of the sensor depends on the adsorbent materials, so specific polymeric materials with particular solubility parameters were chosen to adsorb odorants with various properties. The adsorption properties of the adsorbents could be modified by mixing adsorbent materials. Moreover, a novel molecularly imprinted filtering adsorbent (MIFA), composed of an adsorbent substrate covered with a molecularly imprinted polymer (MIP) layer, was developed to improve the odor molecular recognition ability. The combination of the adsorbent and MIP layer provided a higher specificity toward target molecules. The MIFA thus provides a useful technique for the design and control of adsorbents with adsorption properties specific to particular odor molecules. Full article

(This article belongs to the Special Issue Olfactory and Gustatory Sensors)

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15 pages, 5617 KiB

Open AccessArticle

Peroxynitrite Sensor Based on a Screen Printed Carbon Electrode Modified with a Poly(2,6-dihydroxynaphthalene) Film

by Ioana Silvia Hosu, Diana Constantinescu-Aruxandei, Maria-Luiza Jecu, Florin Oancea

and Mihaela Badea Doni^*

National Institute for Research & Development in Chemistry and Petrochemistry—ICECHIM, Biotechnology Department, 202 Spl. Independentei, Sector 6, Bucharest, Romania

Sensors 2016, 16(11), 1975; https://doi.org/10.3390/s16111975 - 23 Nov 2016

Cited by 8 | Viewed by 6544

Abstract

For the first time the electropolymerization of 2,6-dihydroxynaphthalene (2,6-DHN) on a screen printed carbon electrode (SPCE) was investigated and evaluated for peroxynitrite (PON) detection. Cyclic voltammetry was used to electrodeposit the poly(2,6-DHN) on the carbon electrode surface. The surface morphology and structure of [...] Read more.

For the first time the electropolymerization of 2,6-dihydroxynaphthalene (2,6-DHN) on a screen printed carbon electrode (SPCE) was investigated and evaluated for peroxynitrite (PON) detection. Cyclic voltammetry was used to electrodeposit the poly(2,6-DHN) on the carbon electrode surface. The surface morphology and structure of poly(2,6-DHN) film were investigated by SEM and FTIR analysis, and the electrochemical features by cyclic voltammetry. The poly(2,6-DHN)/SPCE sensor showed excellent electrocatalytic activity for PON oxidation in alkaline solutions at very low potentials (0–100 mV vs. Ag/AgCl pseudoreference). An amperometric FIA (flow injection analysis) system based on the developed sensor was optimized for PON measurements and a linear concentration range from 2 to 300 μM PON, with a LOD of 0.2 μM, was achieved. The optimized sensor inserted in the FIA system exhibited good sensitivity (4.12 nA·μM⁻¹), selectivity, stability and intra-/inter-electrode reproducibility for PON determination. Full article

(This article belongs to the Section Chemical Sensors)

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17 pages, 3264 KiB

Open AccessArticle

Improved Goldstein Interferogram Filter Based on Local Fringe Frequency Estimation

by Qingqing Feng¹, Huaping Xu^1,*, Zhefeng Wu¹, Yanan You¹, Wei Liu²

and Shiqi Ge³

¹ School of Electronic and Information Engineering, Beihang University, Beijing 100191, China

² Electronic and Electrical Engineering Department, University of Sheffield, Sheffield S1 3JD, UK

³ Nanjing Research Institute of Electronics Technology, Nanjing 210039, China

Sensors 2016, 16(11), 1976; https://doi.org/10.3390/s16111976 - 23 Nov 2016

Cited by 36 | Viewed by 6776

Abstract

The quality of an interferogram, which is limited by various phase noise, will greatly affect the further processes of InSAR, such as phase unwrapping. Interferometric SAR (InSAR) geophysical measurements’, such as height or displacement, phase filtering is therefore an essential step. In this [...] Read more.

The quality of an interferogram, which is limited by various phase noise, will greatly affect the further processes of InSAR, such as phase unwrapping. Interferometric SAR (InSAR) geophysical measurements’, such as height or displacement, phase filtering is therefore an essential step. In this work, an improved Goldstein interferogram filter is proposed to suppress the phase noise while preserving the fringe edges. First, the proposed adaptive filter step, performed before frequency estimation, is employed to improve the estimation accuracy. Subsequently, to preserve the fringe characteristics, the estimated fringe frequency in each fixed filtering patch is removed from the original noisy phase. Then, the residual phase is smoothed based on the modified Goldstein filter with its parameter alpha dependent on both the coherence map and the residual phase frequency. Finally, the filtered residual phase and the removed fringe frequency are combined to generate the filtered interferogram, with the loss of signal minimized while reducing the noise level. The effectiveness of the proposed method is verified by experimental results based on both simulated and real data. Full article

(This article belongs to the Section Remote Sensors)

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15 pages, 11254 KiB

Open AccessArticle

Ultra-Low Power Optical Sensor for Xylophagous Insect Detection in Wood

by Angel Perles^*

, Ricardo Mercado, Juan V. Capella

and Juan José Serrano

Instituto ITACA, Universitat Politècnica de València, Camino de Vera, s/n, 46022 Valencia, Spain

Sensors 2016, 16(11), 1977; https://doi.org/10.3390/s16111977 - 23 Nov 2016

Cited by 12 | Viewed by 6607

Abstract

The early detection of pests is key for the maintenance of high-value masterpieces and historical buildings made of wood. In this work, we the present detailed design of an ultra-low power sensor device that permits the continuous monitoring of the presence of termites [...] Read more.

The early detection of pests is key for the maintenance of high-value masterpieces and historical buildings made of wood. In this work, we the present detailed design of an ultra-low power sensor device that permits the continuous monitoring of the presence of termites and other xylophagous insects. The operating principle of the sensor is based on the variations of reflected light induced by the presence of termites, and specific processing algorithms that deal with the behavior of the electronics and the natural ageing of components. With a typical CR2032 lithium battery, the device lasts more than nine years, and is ideal for incorporation in more complex monitoring systems where maintenance tasks should be minimized. Full article

(This article belongs to the Section Physical Sensors)

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16 pages, 11341 KiB

Open AccessArticle

Representation Method for Spectrally Overlapping Signals in Flow Cytometry Based on Fluorescence Pulse Time-Delay Estimation

by Wenchang Zhang^1,2,3

, Xiaoping Lou^2,3, Xiaochen Meng^2,3

and Lianqing Zhu^2,3,*

¹ School of Instrumentation Science & Opto-Electronics Engineering, Hefei University of Technology, Hefei 230009, China

² Beijing Key Laboratory for Optoelectronic Measurement Technology, Beijing Information Science & Technology University, Beijing 100101, China

³ Beijing Laboratory for Biomedical Detection Technology and Instrument, Beijing Information Science and Technology University, Beijing 100101, China

Sensors 2016, 16(11), 1978; https://doi.org/10.3390/s16111978 - 23 Nov 2016

Cited by 3 | Viewed by 7351

Abstract

Flow cytometry is being applied more extensively because of the outstanding advantages of multicolor fluorescence analysis. However, the intensity measurement is susceptible to the nonlinearity of the detection method. Moreover, in multicolor analysis, it is impossible to discriminate between fluorophores that spectrally overlap; [...] Read more.

Flow cytometry is being applied more extensively because of the outstanding advantages of multicolor fluorescence analysis. However, the intensity measurement is susceptible to the nonlinearity of the detection method. Moreover, in multicolor analysis, it is impossible to discriminate between fluorophores that spectrally overlap; this influences the accuracy of the fluorescence pulse signal representation. Here, we focus on spectral overlap in two-color analysis, and assume that the fluorescence follows the single exponential decay model. We overcome these problems by analyzing the influence of the spectral overlap quantitatively, which enables us to propose a method of fluorescence pulse signal representation based on time-delay estimation (between fluorescence and scattered pulse signals). First, the time delays are estimated using a modified chirp Z-transform (MCZT) algorithm and a fine interpolation of the correlation peak (FICP) algorithm. Second, the influence of hardware is removed via calibration, in order to acquire the original fluorescence lifetimes. Finally, modulated signals containing phase shifts associated with these lifetimes are created artificially, using a digital signal processing method, and reference signals are introduced in order to eliminate the influence of spectral overlap. Time-delay estimation simulation and fluorescence signal representation experiments are conducted on fluorescently labeled cells. With taking the potentially overlap of autofluorescence as part of the observed fluorescence spectrum, rather than distinguishing the individual influence, the results show that the calculated lifetimes with spectral overlap can be rectified from 8.28 and 4.86 ns to 8.51 and 4.63 ns, respectively, using the comprehensive approach presented in this work. These values agree well with the lifetimes (8.48 and 4.67 ns) acquired for cells stained with single-color fluorochrome. Further, these results indicate that the influence of spectral overlap can be eliminated effectively. Moreover, modulation, mixing with reference signals, and low-pass filtering are performed with a digital signal processing method, thereby obviating the need for a high-speed analog device and complex circuit system. Finally, the flexibility of the comprehensive method presented in this work is significantly higher than that of existing methods. Full article

(This article belongs to the Section Biosensors)

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22 pages, 1290 KiB

Open AccessArticle

A Testbed to Evaluate the FIWARE-Based IoT Platform in the Domain of Precision Agriculture

by Ramón Martínez, Juan Ángel Pastor

, Bárbara Álvarez

and Andrés Iborra^*

Electronics Engineering and Systems Division (DSIE), Universidad Politécnica de Cartagena, Campus Muralla del Mar s/n, 30202 Cartagena, Murcia, Spain

Sensors 2016, 16(11), 1979; https://doi.org/10.3390/s16111979 - 23 Nov 2016

Cited by 56 | Viewed by 15297

Abstract

Wireless sensor networks (WSNs) represent one of the most promising technologies for precision farming. Over the next few years, a significant increase in the use of such systems on commercial farms is expected. WSNs present a number of problems, regarding scalability, interoperability, communications, [...] Read more.

Wireless sensor networks (WSNs) represent one of the most promising technologies for precision farming. Over the next few years, a significant increase in the use of such systems on commercial farms is expected. WSNs present a number of problems, regarding scalability, interoperability, communications, connectivity with databases and data processing. Different Internet of Things middleware is appearing to overcome these challenges. This paper checks whether one of these middleware, FIWARE, is suitable for the development of agricultural applications. To the authors’ knowledge, there are no works that show how to use FIWARE in precision agriculture and study its appropriateness, its scalability and its efficiency for this kind of applications. To do this, a testbed has been designed and implemented to simulate different deployments and load conditions. The testbed is a typical FIWARE application, complete, yet simple and comprehensible enough to show the main features and components of FIWARE, as well as the complexity of using this technology. Although the testbed has been deployed in a laboratory environment, its design is based on the analysis of an Internet of Things use case scenario in the domain of precision agriculture. Full article

(This article belongs to the Special Issue Enabling the Move from Wireless Sensor Networks to Internet of Things and Cyber-Physical Systems)

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15 pages, 10302 KiB

Open AccessArticle

Radius and Orientation Measurement for Cylindrical Objects by a Light Section Sensor

by Youdong Chen^* and Chongxu Liu

School of Mechanical Engineering & Automation, Beihang University, Beijing 100191, China

Sensors 2016, 16(11), 1981; https://doi.org/10.3390/s16111981 - 23 Nov 2016

Cited by 10 | Viewed by 8151

Abstract

In this paper, an efficient method based on a light section sensor is presented for measuring cylindrical objects’ radii and orientations in a robotic application. By this method, the cylindrical objects can be measured under some special conditions, such as when the cylindrical [...] Read more.

In this paper, an efficient method based on a light section sensor is presented for measuring cylindrical objects’ radii and orientations in a robotic application. By this method, the cylindrical objects can be measured under some special conditions, such as when the cylindrical objects are welded with others, or in the presence of interferences. Firstly, the measurement data are roughly identified and accurately screened to effectively recognize ellipses. Secondly, the data are smoothed and homogenized to eliminate the effect of laser line loss or jump and reduce the influence of the inhomogeneity of measurement data on the ellipse fitting to a minimum. Finally, the ellipse fitting is carried out to obtain the radii and orientations of the cylindrical objects. Measuring experiments and results demonstrate the effective of the proposed radius and orientation measurement method for cylindrical object. Full article

(This article belongs to the Section Physical Sensors)

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