Sensors

Editorial

Jump to: Research, Review

7 pages, 627 KiB

Open AccessEditorial

Advances in Target Detection and Tracking in Forward-Looking InfraRed (FLIR) Imagery

by Andrea Sanna^*

and Fabrizio Lamberti

Politecnico di Torino, Dipartimento di Automatica e Informatica, Corso Duca degli Abruzzi 24, Torino 10129, Italy

Sensors 2014, 14(11), 20297-20303; https://doi.org/10.3390/s141120297 - 28 Oct 2014

Cited by 26 | Viewed by 7087

Abstract

Here we give context to the Special Issue on “Detection and Tracking of Targets in Forward-Looking InfraRed (FLIR) Imagery” in Sensors. We start with an introduction to the role of infrared images in today’s vision-based applications, by outlining the specific challenges that characterize [...] Read more.

Here we give context to the Special Issue on “Detection and Tracking of Targets in Forward-Looking InfraRed (FLIR) Imagery” in Sensors. We start with an introduction to the role of infrared images in today’s vision-based applications, by outlining the specific challenges that characterize detection and tracking in FLIR images. We then illustrate why selected papers have been chosen to represent the domain of interest, by summarizing their main contributions to the state-of-the-art. Lastly, we sum up the main evidence found, and we underline some of the aspects that are worthy of further investigation in future research activities. Full article

(This article belongs to the Special Issue Detection and Tracking of Targets in Forward-Looking InfraRed (FLIR) Imagery)

4 pages, 628 KiB

Open AccessEditorial

Magnetic Resonance Sensors

by Robert H. Morris^* and Michael I. Newton

School of Science and Technology, Nottingham Trent University, Clifton Lane, Nottingham, NG11 8NS, UK

Sensors 2014, 14(11), 21722-21725; https://doi.org/10.3390/s141121722 - 17 Nov 2014

Cited by 1 | Viewed by 6153

Abstract

Magnetic Resonance finds countless applications, from spectroscopy to imaging, routinely in almost all research and medical institutions across the globe. It is also becoming more frequently used for specific applications in which the whole instrument and system is designed for a dedicated application. [...] Read more.

Magnetic Resonance finds countless applications, from spectroscopy to imaging, routinely in almost all research and medical institutions across the globe. It is also becoming more frequently used for specific applications in which the whole instrument and system is designed for a dedicated application. With beginnings in borehole logging for the petro-chemical industry Magnetic Resonance sensors have been applied to fields as varied as online process monitoring for food manufacture and medical point of care diagnostics. This great diversity is seeing exciting developments in magnetic resonance sensing technology published in application specific journals where they are often not seen by the wider sensor community. It is clear that there is enormous interest in magnetic resonance sensors which represents a significant growth area. The aim of this special edition of Sensors was to address the wide distribution of relevant articles by providing a forum to disseminate cutting edge research in this field in a single open source publication.[...] Full article

(This article belongs to the Special Issue Magnetic Resonance Sensors)

Research

Jump to: Editorial, Review

19 pages, 2237 KiB

Open AccessArticle

Videosensor for the Detection of Unsafe Driving Behavior in the Proximity of Black Spots

by Andres Fuentes^1,*, Ricardo Fuentes¹, Enrique Cabello², Cristina Conde² and Isaac Martin²

¹ Universidad de Colima (UCol), Mexico, Ave. Universidad #333, Colonia Las Víboras, Colima 28050, Mexico

² Universidad Rey Juan Carlos (URJC), Escuela Tecnica Superior de Ingenieria Informatica, Tulipán s/n, Móstoles, Madrid 28933, Spain

Sensors 2014, 14(11), 19926-19944; https://doi.org/10.3390/s141119926 - 24 Oct 2014

Cited by 4 | Viewed by 8508

Abstract

This paper discusses the overall design and implementation of a video sensor for the detection of risky behaviors of car drivers near previously identified and georeferenced black spots. The main goal is to provide the driver with a visual audio alert that informs [...] Read more.

This paper discusses the overall design and implementation of a video sensor for the detection of risky behaviors of car drivers near previously identified and georeferenced black spots. The main goal is to provide the driver with a visual audio alert that informs of the proximity of an area of high incidence of highway accidents only if their driving behavior could result in a risky situation. It proposes a video sensor for detecting and supervising driver behavior, its main objective being manual distractions, so hand driver supervision is performed. A GPS signal is also considered, the GPS information is compared with a database of global positioning Black Spots to determine the relative proximity of a risky area. The outputs of the video sensor and GPS sensor are combined to evaluate a possible risky behavior. The results are promising in terms of risk analysis in order to be validated for use in the context of the automotive industry as future work. Full article

(This article belongs to the Special Issue Positioning and Tracking Sensors and Technologies in Road Transport)

▼ Show Figures

18 pages, 1041 KiB

Open AccessArticle

Detection of Foreign Matter in Transfusion Solution Based on Gaussian Background Modeling and an Optimized BP Neural Network

by Fuqiang Zhou^*, Zhen Su, Xinghua Chai

and Lipeng Chen

School of Instrumentation Science and Optoelectronics Engineering, Beihang University, XueYuan Road No. 37, Haidian District, Beijing 100191, China

Sensors 2014, 14(11), 19945-19962; https://doi.org/10.3390/s141119945 - 24 Oct 2014

Cited by 10 | Viewed by 6073

Abstract

This paper proposes a new method to detect and identify foreign matter mixed in a plastic bottle filled with transfusion solution. A spin-stop mechanism and mixed illumination style are applied to obtain high contrast images between moving foreign matter and a static transfusion [...] Read more.

This paper proposes a new method to detect and identify foreign matter mixed in a plastic bottle filled with transfusion solution. A spin-stop mechanism and mixed illumination style are applied to obtain high contrast images between moving foreign matter and a static transfusion background. The Gaussian mixture model is used to model the complex background of the transfusion image and to extract moving objects. A set of features of moving objects are extracted and selected by the ReliefF algorithm, and optimal feature vectors are fed into the back propagation (BP) neural network to distinguish between foreign matter and bubbles. The mind evolutionary algorithm (MEA) is applied to optimize the connection weights and thresholds of the BP neural network to obtain a higher classification accuracy and faster convergence rate. Experimental results show that the proposed method can effectively detect visible foreign matter in 250-mL transfusion bottles. The misdetection rate and false alarm rate are low, and the detection accuracy and detection speed are satisfactory. Full article

(This article belongs to the Section Physical Sensors)

▼ Show Figures

16 pages, 3224 KiB

Open AccessArticle

An Embedded Stress Sensor for Concrete SHM Based on Amorphous Ferromagnetic Microwires

by Jesús Olivera^1,*, Margarita González¹, José Vicente Fuente², Rastislav Varga³, Arkady Zhukov^4,5

and José Javier Anaya¹

¹ Instituto de Tecnologías Físicas y de la Información "Leonardo Torres Quevedo", ITEFI (CSIC), Madrid 28006, Spain

² Instituto Tecnológico de la Construcción (AIDICO), Valencia 46980, Spain

³ Institute of Physics, Faculty of Science, University of Pavol Jozef Safarik, Kosice 040 01, Slovakia

⁴ Dpto. Física de Materiales, Facultad de Química, UPV/EHU, San Sebastián 20018, Spain

⁵ IKERBASQUE, Basque Foundation for Science, Bilbao 48011, Spain

Sensors 2014, 14(11), 19963-19978; https://doi.org/10.3390/s141119963 - 24 Oct 2014

Cited by 48 | Viewed by 8500

Abstract

A new smart concrete aggregate design as a candidate for applications in structural health monitoring (SHM) of critical elements in civil infrastructure is proposed. The cement-based stress/strain sensor was developed by utilizing the stress/strain sensing properties of a magnetic microwire embedded in cement-based [...] Read more.

A new smart concrete aggregate design as a candidate for applications in structural health monitoring (SHM) of critical elements in civil infrastructure is proposed. The cement-based stress/strain sensor was developed by utilizing the stress/strain sensing properties of a magnetic microwire embedded in cement-based composite (MMCC). This is a contact-less type sensor that measures variations of magnetic properties resulting from stress variations. Sensors made of these materials can be designed to satisfy the specific demand for an economic way to monitor concrete infrastructure health. For this purpose, we embedded a thin magnetic microwire in the core of a cement-based cylinder, which was inserted into the concrete specimen under study as an extra aggregate. The experimental results show that the embedded MMCC sensor is capable of measuring internal compressive stress around the range of 1–30 MPa. Two stress sensing properties of the embedded sensor under uniaxial compression were studied: the peak amplitude and peak position of magnetic switching field. The sensitivity values for the amplitude and position within the measured range were 5 mV/MPa and 2.5 µs/MPa, respectively. Full article

(This article belongs to the Special Issue Novel Sensors for Non-Destructive Testing and Structural Health Monitoring)

▼ Show Figures

17 pages, 1198 KiB

Open AccessArticle

Accurate Orientation Estimation Using AHRS under Conditions of Magnetic Distortion

by Nagesh Yadav^* and Chris Bleakley

Complex and Adaptive Systems Laboratory, School of Computer Science and Informatics, University College Dublin, Dublin 4, Ireland

Sensors 2014, 14(11), 20008-20024; https://doi.org/10.3390/s141120008 - 24 Oct 2014

Cited by 88 | Viewed by 11853

Abstract

Low cost, compact attitude heading reference systems (AHRS) are now being used to track human body movements in indoor environments by estimation of the 3D orientation of body segments. In many of these systems, heading estimation is achieved by monitoring the strength of [...] Read more.

Low cost, compact attitude heading reference systems (AHRS) are now being used to track human body movements in indoor environments by estimation of the 3D orientation of body segments. In many of these systems, heading estimation is achieved by monitoring the strength of the Earth’s magnetic field. However, the Earth’s magnetic field can be locally distorted due to the proximity of ferrous and/or magnetic objects. Herein, we propose a novel method for accurate 3D orientation estimation using an AHRS, comprised of an accelerometer, gyroscope and magnetometer, under conditions of magnetic field distortion. The system performs online detection and compensation for magnetic disturbances, due to, for example, the presence of ferrous objects. The magnetic distortions are detected by exploiting variations in magnetic dip angle, relative to the gravity vector, and in magnetic strength. We investigate and show the advantages of using both magnetic strength and magnetic dip angle for detecting the presence of magnetic distortions. The correction method is based on a particle filter, which performs the correction using an adaptive cost function and by adapting the variance during particle resampling, so as to place more emphasis on the results of dead reckoning of the gyroscope measurements and less on the magnetometer readings. The proposed method was tested in an indoor environment in the presence of various magnetic distortions and under various accelerations (up to 3 g). In the experiments, the proposed algorithm achieves <2° static peak-to-peak error and <5° dynamic peak-to-peak error, significantly outperforming previous methods. Full article

(This article belongs to the Section Physical Sensors)

▼ Show Figures

16 pages, 6653 KiB

Open AccessArticle

Boresight Calibration of Construction Misalignments for 3D Scanners Built with a 2D Laser Rangefinder Rotating on Its Optical Center

by Jesús Morales^1,*

, Jorge L. Martínez¹

, Anthony Mandow¹

, Antonio J. Reina¹, Alejandro Pequeño-Boter² and Alfonso García-Cerezo¹

¹ Departamento de Ingeniería de Sistemas y Automática, Universidad de Málaga, Andalucía Tech, 29071-Málaga, Spain

² Ingeniería UNO, Calle Alcalde Garret y Souto, 38, 29006-Málaga, Spain

Sensors 2014, 14(11), 20025-20040; https://doi.org/10.3390/s141120025 - 24 Oct 2014

Cited by 32 | Viewed by 8402

Abstract

Many applications, like mobile robotics, can profit from acquiring dense, wide-ranging and accurate 3D laser data. Off-the-shelf 2D scanners are commonly customized with an extra rotation as a low-cost, lightweight and low-power-demanding solution. Moreover, aligning the extra rotation axis with the optical center [...] Read more.

Many applications, like mobile robotics, can profit from acquiring dense, wide-ranging and accurate 3D laser data. Off-the-shelf 2D scanners are commonly customized with an extra rotation as a low-cost, lightweight and low-power-demanding solution. Moreover, aligning the extra rotation axis with the optical center allows the 3D device to maintain the same minimum range as the 2D scanner and avoids offsets in computing Cartesian coordinates. The paper proposes a practical procedure to estimate construction misalignments based on a single scan taken from an arbitrary position in an unprepared environment that contains planar surfaces of unknown dimensions. Inherited measurement limitations from low-cost 2D devices prevent the estimation of very small translation misalignments, so the calibration problem reduces to obtaining boresight parameters. The distinctive approach with respect to previous plane-based intrinsic calibration techniques is the iterative maximization of both the flatness and the area of visible planes. Calibration results are presented for a case study. The method is currently being applied as the final stage in the production of a commercial 3D rangefinder. Full article

(This article belongs to the Section Physical Sensors)

▼ Show Figures

23 pages, 11556 KiB

Open AccessArticle

Structured-Light Sensor Using Two Laser Stripes for 3D Reconstruction without Vibrations

by Rubén Usamentiaga^*

, Julio Molleda and Daniel F. Garcia

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

Sensors 2014, 14(11), 20041-20063; https://doi.org/10.3390/s141120041 - 24 Oct 2014

Cited by 22 | Viewed by 7273

Abstract

3D reconstruction based on laser light projection is a well-known method that generally provides accurate results. However, when this method is used for inspection in uncontrolled environments, it is greatly affected by vibrations. This paper presents a structured-light sensor based on two laser [...] Read more.

3D reconstruction based on laser light projection is a well-known method that generally provides accurate results. However, when this method is used for inspection in uncontrolled environments, it is greatly affected by vibrations. This paper presents a structured-light sensor based on two laser stripes that provides a 3D reconstruction without vibrations. Using more than one laser stripe provides redundant information than is used to compensate for the vibrations. This work also proposes an accurate calibration process for the sensor based on standard calibration plates. A series of experiments are performed to evaluate the proposed method using a mechanical device that simulates vibrations. Results show excellent performance, with very good accuracy. Full article

(This article belongs to the Section Physical Sensors)

▼ Show Figures

14 pages, 354 KiB

Open AccessArticle

An Efficient Algorithm for Direction Finding against Unknown Mutual Coupling

by Weijiang Wang, Shiwei Ren

, Yingtao Ding^* and Haoyu Wang

School of Information and Electronics, Beijing Institute of Technology, 5 South Zhongguancun Street, Haidian District, Beijing 100081, China

Sensors 2014, 14(11), 20064-20077; https://doi.org/10.3390/s141120064 - 24 Oct 2014

Cited by 11 | Viewed by 5051

Abstract

In this paper, an algorithm of direction finding is proposed in the presence of unknown mutual coupling. The preliminary direction of arrival (DOA) is estimated using the whole array for high resolution. Further refinement can then be conducted by estimating the angularly dependent [...] Read more.

In this paper, an algorithm of direction finding is proposed in the presence of unknown mutual coupling. The preliminary direction of arrival (DOA) is estimated using the whole array for high resolution. Further refinement can then be conducted by estimating the angularly dependent coefficients (ADCs) with the subspace theory. The mutual coupling coefficients are finally determined by solving the least squares problem with all of the ADCs utilized without discarding any. Simulation results show that the proposed method can achieve better performance at a low signal-to-noise ratio (SNR) with a small-sized array and is more robust, compared with the similar processes employing the initial DOA estimation and further improvement iteratively. Full article

(This article belongs to the Section Physical Sensors)

▼ Show Figures

22 pages, 5092 KiB

Open AccessArticle

Laser Spot Tracking Based on Modified Circular Hough Transform and Motion Pattern Analysis

by Damir Krstinić, Ana Kuzmanić Skelin^* and Ivan Milatić

Faculty of Electrical Engineering, Mechanical Engineering and Naval Architecture, University of Split, R. Boškovića 32, Split 21000, Croatia

Sensors 2014, 14(11), 20112-20133; https://doi.org/10.3390/s141120112 - 27 Oct 2014

Cited by 18 | Viewed by 8953

Abstract

Laser pointers are one of the most widely used interactive and pointing devices in different human-computer interaction systems. Existing approaches to vision-based laser spot tracking are designed for controlled indoor environments with the main assumption that the laser spot is very bright, if [...] Read more.

Laser pointers are one of the most widely used interactive and pointing devices in different human-computer interaction systems. Existing approaches to vision-based laser spot tracking are designed for controlled indoor environments with the main assumption that the laser spot is very bright, if not the brightest, spot in images. In this work, we are interested in developing a method for an outdoor, open-space environment, which could be implemented on embedded devices with limited computational resources. Under these circumstances, none of the assumptions of existing methods for laser spot tracking can be applied, yet a novel and fast method with robust performance is required. Throughout the paper, we will propose and evaluate an efficient method based on modified circular Hough transform and Lucas–Kanade motion analysis. Encouraging results on a representative dataset demonstrate the potential of our method in an uncontrolled outdoor environment, while achieving maximal accuracy indoors. Our dataset and ground truth data are made publicly available for further development. Full article

(This article belongs to the Special Issue HCI In Smart Environments)

▼ Show Figures

15 pages, 1242 KiB

Open AccessArticle

A Rapid Discrimination of Authentic and Unauthentic Radix Angelicae Sinensis Growth Regions by Electronic Nose Coupled with Multivariate Statistical Analyses

by Jie Liu¹, Weixin Wang², Yaojun Yang^1,*, Yuning Yan¹, Wenyi Wang¹, Haozhong Wu¹ and Zihe Ren³

¹ School of Chinese Materia Medica, Beijing University of Chinese Medicine, No.6 Wangjing Zhonghuan South Road, Beijing 100102, China

² Institute of Forensic Science, Ministry of Public Security, No.17 Muxidi South Street Xicheng District, Beijing 100038, China

³ Yinkou Institute For Drug, NO.29 Qinghua West Street, Xishi District, Yingkou 115100, China

Sensors 2014, 14(11), 20134-20148; https://doi.org/10.3390/s141120134 - 27 Oct 2014

Cited by 22 | Viewed by 5802

Abstract

Radix Angelicae Sinensis, known as Danggui in China, is an effective and wide applied material in Traditional Chinese Medicine (TCM) and it is used in more than 80 composite formulae. Danggui from Minxian County, Gansu Province is the best in quality. To rapidly [...] Read more.

Radix Angelicae Sinensis, known as Danggui in China, is an effective and wide applied material in Traditional Chinese Medicine (TCM) and it is used in more than 80 composite formulae. Danggui from Minxian County, Gansu Province is the best in quality. To rapidly and nondestructively discriminate Danggui from the authentic region of origin from that from an unauthentic region, an electronic nose coupled with multivariate statistical analyses was developed. Two different feature extraction methods were used to ensure the authentic region and unauthentic region of Danggui origin could be discriminated. One feature extraction method is to capture the average value of the maximum response of the electronic nose sensors (feature extraction method 1). The other one is to combine the maximum response of the sensors with their inter-ratios (feature extraction method 2). Multivariate statistical analyses, including principal component analysis (PCA), soft independent modeling of class analogy (SIMCA), and hierarchical clustering analysis (HCA) were employed. Nineteen samples were analyzed by PCA, SIMCA and HCA. Then the remaining samples (GZM1, SH) were projected onto the SIMCA model to validate the models. The results indicated that, in the use of feature extraction method 2, Danggui from Yunnan Province and Danggui from Gansu Province could be successfully discriminated using the electronic nose coupled with PCA, SIMCA and HCA, which suggested that the electronic-nose system could be used as a simple and rapid technique for the discrimination of Danggui between authentic and unauthentic region of origin. Full article

(This article belongs to the Section Chemical Sensors)

▼ Show Figures

16 pages, 1853 KiB

Open AccessArticle

A Study of the Effect of the Fringe Fields on the Electrostatic Force in Vertical Comb Drives

by Else Gallagher and Walied Moussa^*

Department of Mechanical Engineering, University of Alberta, 4-9 Mechanical Engineering Building, Edmonton, AB T6G 2G8, Canada

Sensors 2014, 14(11), 20149-20164; https://doi.org/10.3390/s141120149 - 27 Oct 2014

Cited by 11 | Viewed by 5578

Abstract

The equation that describes the relationship between the applied voltage and the resulting electrostatic force within comb drives is often used to assist in choosing the dimensions for their design. This paper re-examines how some of these dimensions—particularly the cross-sectional dimensions of the [...] Read more.

The equation that describes the relationship between the applied voltage and the resulting electrostatic force within comb drives is often used to assist in choosing the dimensions for their design. This paper re-examines how some of these dimensions—particularly the cross-sectional dimensions of the comb teeth—affect this relationship in vertical comb drives. The electrostatic forces in several vertical comb drives fabricated for this study were measured and compared to predictions made with four different mathematical models in order to explore the amount of complexity required within a model to accurately predict the electrostatic forces in the comb drives. Full article

(This article belongs to the Section Physical Sensors)

▼ Show Figures

23 pages, 338 KiB

Open AccessArticle

Antenna Allocation in MIMO Radar with Widely Separated Antennas for Multi-Target Detection

by Hao Gao, Jian Wang, Chunxiao Jiang and Xudong Zhang^*

Department of Electronic Engineering, Tsinghua University, Beijing 100084, China

Sensors 2014, 14(11), 20165-20187; https://doi.org/10.3390/s141120165 - 27 Oct 2014

Cited by 12 | Viewed by 6004

Abstract

In this paper, we explore a new resource called multi-target diversity to optimize the performance of multiple input multiple output (MIMO) radar with widely separated antennas for detecting multiple targets. In particular, we allocate antennas of the MIMO radar to probe different targets [...] Read more.

In this paper, we explore a new resource called multi-target diversity to optimize the performance of multiple input multiple output (MIMO) radar with widely separated antennas for detecting multiple targets. In particular, we allocate antennas of the MIMO radar to probe different targets simultaneously in a flexible manner based on the performance metric of relative entropy. Two antenna allocation schemes are proposed. In the first scheme, each antenna is allocated to illuminate a proper target over the entire illumination time, so that the detection performance of each target is guaranteed. The problem is formulated as a minimum makespan scheduling problem in the combinatorial optimization framework. Antenna allocation is implemented through a branch-and-bound algorithm and an enhanced factor 2 algorithm. In the second scheme, called antenna-time allocation, each antenna is allocated to illuminate different targets with different illumination time. Both antenna allocation and time allocation are optimized based on illumination probabilities. Over a large range of transmitted power, target fluctuations and target numbers, both of the proposed antenna allocation schemes outperform the scheme without antenna allocation. Moreover, the antenna-time allocation scheme achieves a more robust detection performance than branch-and-bound algorithm and the enhanced factor 2 algorithm when the target number changes. Full article

(This article belongs to the Section Physical Sensors)

▼ Show Figures

29 pages, 1776 KiB

Open AccessArticle

Using Hybrid Angle/Distance Information for Distributed Topology Control in Vehicular Sensor Networks

by Chao-Chi Huang, Yang-Hung Chiu and Chih-Yu Wen^*

Department of Electrical Engineering, Graduate Institute of Communication Engineering, National Chung Hsing University, Taichung 402, Taiwan

Sensors 2014, 14(11), 20188-20216; https://doi.org/10.3390/s141120188 - 27 Oct 2014

Cited by 10 | Viewed by 6120

Abstract

In a vehicular sensor network (VSN), the key design issue is how to organize vehicles effectively, such that the local network topology can be stabilized quickly. In this work, each vehicle with on-board sensors can be considered as a local controller associated with [...] Read more.

In a vehicular sensor network (VSN), the key design issue is how to organize vehicles effectively, such that the local network topology can be stabilized quickly. In this work, each vehicle with on-board sensors can be considered as a local controller associated with a group of communication members. In order to balance the load among the nodes and govern the local topology change, a group formation scheme using localized criteria is implemented. The proposed distributed topology control method focuses on reducing the rate of group member change and avoiding the unnecessary information exchange. Two major phases are sequentially applied to choose the group members of each vehicle using hybrid angle/distance information. The operation of Phase I is based on the concept of the cone-based method, which can select the desired vehicles quickly. Afterwards, the proposed time-slot method is further applied to stabilize the network topology. Given the network structure in Phase I, a routing scheme is presented in Phase II. The network behaviors are explored through simulation and analysis in a variety of scenarios. The results show that the proposed mechanism is a scalable and effective control framework for VSNs. Full article

(This article belongs to the Special Issue Wireless Sensor Networks and the Internet of Things)

▼ Show Figures

18 pages, 865 KiB

Open AccessArticle

Modeling Apple Surface Temperature Dynamics Based on Weather Data

by Lei Li^1,2,3, Troy Peters³, Qin Zhang³, Jingjin Zhang³ and Danfeng Huang^2,*

¹ School of Mechanical Engineering, Shanghai Jiaotong University, Shanghai 200240, China

² School of Agriculture and Biology, Shanghai Jiaotong University, Shanghai 200240, China

³ Center for Precision & Automated Agricultural Systems, Washington State University, 24106 North Bunn Rd., Prosser, WA 99350, USA

Sensors 2014, 14(11), 20217-20234; https://doi.org/10.3390/s141120217 - 27 Oct 2014

Cited by 31 | Viewed by 8244

Abstract

The exposure of fruit surfaces to direct sunlight during the summer months can result in sunburn damage. Losses due to sunburn damage are a major economic problem when marketing fresh apples. The objective of this study was to develop and validate a model [...] Read more.

The exposure of fruit surfaces to direct sunlight during the summer months can result in sunburn damage. Losses due to sunburn damage are a major economic problem when marketing fresh apples. The objective of this study was to develop and validate a model for simulating fruit surface temperature (FST) dynamics based on energy balance and measured weather data. A series of weather data (air temperature, humidity, solar radiation, and wind speed) was recorded for seven hours between 11:00–18:00 for two months at fifteen minute intervals. To validate the model, the FSTs of “Fuji” apples were monitored using an infrared camera in a natural orchard environment. The FST dynamics were measured using a series of thermal images. For the apples that were completely exposed to the sun, the RMSE of the model for estimating FST was less than 2.0 °C. A sensitivity analysis of the emissivity of the apple surface and the conductance of the fruit surface to water vapour showed that accurate estimations of the apple surface emissivity were important for the model. The validation results showed that the model was capable of accurately describing the thermal performances of apples under different solar radiation intensities. Thus, this model could be used to more accurately estimate the FST relative to estimates that only consider the air temperature. In addition, this model provides useful information for sunburn protection management. Full article

(This article belongs to the Special Issue Sensors in Agriculture and Forestry)

▼ Show Figures

10 pages, 1124 KiB

Open AccessArticle

Study of a Liquid Plug-Flow Thermal Cycling Technique Using a Temperature Gradient-Based Actuator

by Yusuke Fuchiwaki^1,2,* and Hidenori Nagai³

¹ Health Research Institute, National Institute of Advanced Industrial Science and Technology (AIST), 2217-14, Hayashi-cho, Takamatsu, Kagawa 761-0395, Japan

² CEA-LETI, Minatec Campus, 17 rue des Martyrs, 38054 Grenoble Cedex 9, France

³ Health Research Institute, National Institute of Advanced Industrial Science and Technology (AIST), 1-8-31 Midorigaoka, Ikeda, Osaka 563-8577, Japan

Sensors 2014, 14(11), 20235-20244; https://doi.org/10.3390/s141120235 - 27 Oct 2014

Cited by 10 | Viewed by 6539

Abstract

Easy-to-use thermal cycling for performing rapid and small-volume DNA amplification on a single chip has attracted great interest in the area of rapid field detection of biological agents. For this purpose, as a more practical alternative to conventional continuous flow thermal cycling, liquid [...] Read more.

Easy-to-use thermal cycling for performing rapid and small-volume DNA amplification on a single chip has attracted great interest in the area of rapid field detection of biological agents. For this purpose, as a more practical alternative to conventional continuous flow thermal cycling, liquid plug-flow thermal cycling utilizes a thermal gradient generated in a serpentine rectangular flow microchannel as an actuator. The transit time and flow speed of the plug flow varied drastically in each temperature zone due to the difference in the tension at the interface between temperature gradients. According to thermal distribution analyses in microfluidics, the plug flow allowed for a slow heating process, but a fast cooling process. The thermal cycle of the microfluid was consistent with the recommended temperature gradient for PCR. Indeed, amplification efficiency of the plug flow was superior to continuous flow PCR, and provided an impressive improvement over previously-reported flow microchannel thermal cycling techniques. Full article

(This article belongs to the Special Issue Sensors for Bioprocess Monitoring and Control)

▼ Show Figures

17 pages, 1132 KiB

Open AccessArticle

Micro-Fabricated DC Comparison Calorimeter for RF Power Measurement

by Bilel Neji¹, Jing Xu¹, Albert H. Titus^1,* and Joel Meltzer²

¹ Department of Electrical Engineering, University at Buffalo, The State University of New York, Buffalo, NY 14260, USA

² Bird Technologies, Solon, OH 44139, USA

Sensors 2014, 14(11), 20245-20261; https://doi.org/10.3390/s141120245 - 27 Oct 2014

Cited by 4 | Viewed by 7778

Abstract

Diode detection and bolometric detection have been widely used to measure radio frequency (RF) power. However, flow calorimeters, in particular micro-fabricated flow calorimeters, have been mostly unexplored as power meters. This paper presents the design, micro-fabrication and characterization of a flow calorimeter. This [...] Read more.

Diode detection and bolometric detection have been widely used to measure radio frequency (RF) power. However, flow calorimeters, in particular micro-fabricated flow calorimeters, have been mostly unexplored as power meters. This paper presents the design, micro-fabrication and characterization of a flow calorimeter. This novel device is capable of measuring power from 100 \(\mu\)W to 200 mW. It has a 50-Ohm load that is heated by the RF source, and the heat is transferred to fluid in a microchannel. The temperature change in the fluid is measured by a thermistor that is connected in one leg of a Wheatstone bridge. The output voltage change of the bridge corresponds to the RF power applied to the load. The microfabricated device measures 25.4 mm \(\times\) 50.8 mm, excluding the power supplies, microcontroller and fluid pump. Experiments demonstrate that the micro-fabricated sensor has a sensitivity up to 22 \(\times\) \(10^{-3}\) V/W. The typical resolution of this micro-calorimeter is on the order of 50 \(\mu\)W, and the best resolution is around 10 \(\mu\)W. The effective efficiency is 99.9\% from 0–1 GHz and more than 97.5\% at frequencies up to 4 GHz. The measured reflection coefficient of the 50-Ohm load and coplanar wave guide is less than \(-25\) dB from 0–2 GHz and less than \(-16\) dB at 2–4 GHz. Full article

(This article belongs to the Special Issue On-Chip Sensors)

▼ Show Figures

12 pages, 3826 KiB

Open AccessArticle

Development of a Portable 3CCD Camera System for Multispectral Imaging of Biological Samples

by Hoyoung Lee¹, Soo Hyun Park², Sang Ha Noh², Jongguk Lim³

and Moon S. Kim^1,*

¹ Environmental Microbial and Food Safety Laboratory, Beltsville Agricultural Research Center Agricultural Research Service, United States Department of Agriculture, 10300 Baltimore Ave, Beltsville, MD 20705, USA

² Department of Biosystems & Biomaterials Science and Engineering, Seoul National University, Seoul 151-921, Korea

³ National Academy of Agricultural Science, Rural Development Administration, 150 Suinro, Gwonseon-gu, Suwon, Gyeonggi-do 441-100, Korea

Sensors 2014, 14(11), 20262-20273; https://doi.org/10.3390/s141120262 - 27 Oct 2014

Cited by 11 | Viewed by 9197

Abstract

Recent studies have suggested the need for imaging devices capable of multispectral imaging beyond the visible region, to allow for quality and safety evaluations of agricultural commodities. Conventional multispectral imaging devices lack flexibility in spectral waveband selectivity for such applications. In this paper, [...] Read more.

Recent studies have suggested the need for imaging devices capable of multispectral imaging beyond the visible region, to allow for quality and safety evaluations of agricultural commodities. Conventional multispectral imaging devices lack flexibility in spectral waveband selectivity for such applications. In this paper, a recently developed portable 3CCD camera with significant improvements over existing imaging devices is presented. A beam-splitter prism assembly for 3CCD was designed to accommodate three interference filters that can be easily changed for application-specific multispectral waveband selection in the 400 to 1000 nm region. We also designed and integrated electronic components on printed circuit boards with firmware programming, enabling parallel processing, synchronization, and independent control of the three CCD sensors, to ensure the transfer of data without significant delay or data loss due to buffering. The system can stream 30 frames (3-waveband images in each frame) per second. The potential utility of the 3CCD camera system was demonstrated in the laboratory for detecting defect spots on apples. Full article

(This article belongs to the Section Physical Sensors)

▼ Show Figures

23 pages, 2792 KiB

Open AccessArticle

A Modular Localization System as a Positioning Service for Road Transport

by Peter Brida

, Juraj Machaj^*

and Jozef Benikovsky

Department of Telecommunications and Multimedia, Faculty of Electrical Engineering, University of Zilina, Univerzitna 1, Zilina 010 26, Slovakia

Sensors 2014, 14(11), 20274-20296; https://doi.org/10.3390/s141120274 - 28 Oct 2014

Cited by 21 | Viewed by 6711

Abstract

In recent times smart devices have attracted a large number of users. Since many of these devices allow position estimation using Global Navigation Satellite Systems (GNSS) signals, a large number of location-based applications and services have emerged, especially in transport systems. However GNSS [...] Read more.

In recent times smart devices have attracted a large number of users. Since many of these devices allow position estimation using Global Navigation Satellite Systems (GNSS) signals, a large number of location-based applications and services have emerged, especially in transport systems. However GNSS signals are affected by the environment and are not always present, especially in dense urban environment or indoors. In this work firstly a Modular Localization Algorithm is proposed to allow seamless switching between different positioning modules. This helps us develop a positioning system that is able to provide position estimates in both indoor and outdoor environments without any user interaction. Since the proposed system can run as a service on any smart device, it could allow users to navigate not only in outdoor environments, but also indoors, e.g., underground garages, tunnels etc. Secondly we present the proposal of a 2-phase map reduction algorithm which allows one to significantly reduce the complexity of position estimation processes in case that positioning is performed using a fingerprinting framework. The proposed 2-phase map reduction algorithm can also improve the accuracy of the position estimates by filtering out reference points that are far from the mobile device. Both algorithms were implemented into a positioning system and tested in real world conditions in both indoor and outdoor environments. Full article

(This article belongs to the Special Issue Positioning and Tracking Sensors and Technologies in Road Transport)

▼ Show Figures

16 pages, 2138 KiB

Open AccessArticle

Terrestrial Laser Scanning for Vegetation Sampling

by Jeffrey J Richardson^*, L. Monika Moskal

and Jonathan D. Bakker

School of Environmental and Forest Sciences, University of Washington, Box 352100, Seattle, WA 98195-2100, USA

Sensors 2014, 14(11), 20304-20319; https://doi.org/10.3390/s141120304 - 28 Oct 2014

Cited by 21 | Viewed by 7236

Abstract

We developed new vegetation indices utilizing terrestrial laser scanning (TLS) to quantify the three-dimensional spatial configuration of plant communities. These indices leverage the novelty of TLS data and rely on the spatially biased arrangement of a TLS point cloud. We calculated these indices [...] Read more.

We developed new vegetation indices utilizing terrestrial laser scanning (TLS) to quantify the three-dimensional spatial configuration of plant communities. These indices leverage the novelty of TLS data and rely on the spatially biased arrangement of a TLS point cloud. We calculated these indices from TLS data acquired within an existing long term manipulation of forest structure in Central Oregon, USA, and used these data to test for differences in vegetation structure. Results provided quantitative evidence of a significant difference in vegetation density due to thinning and burning, and a marginally significant difference in vegetation patchiness due to grazing. A comparison to traditional field sampling highlighted the novelty of the TLS based method. By creating a linkage between traditional field sampling and landscape ecology, these indices enable field investigations of fine-scale spatial patterns. Applications include experimental assessment, long-term monitoring, and habitat characterization. Full article

(This article belongs to the Section Remote Sensors)

▼ Show Figures

27 pages, 2354 KiB

Open AccessArticle

Multi-Fault Detection of Rolling Element Bearings under Harsh Working Condition Using IMF-Based Adaptive Envelope Order Analysis

by Ming Zhao¹

, Jing Lin^2,*, Xiaoqiang Xu¹ and Xuejun Li³

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

³ College of Mechanical and Electrical Engineering, Hunan University of Science and Technology, Xiangtan 411201, China

Sensors 2014, 14(11), 20320-20346; https://doi.org/10.3390/s141120320 - 28 Oct 2014

Cited by 49 | Viewed by 7488

Abstract

When operating under harsh condition (e.g., time-varying speed and load, large shocks), the vibration signals of rolling element bearings are always manifested as low signal noise ratio, non-stationary statistical parameters, which cause difficulties for current diagnostic methods. As such, an IMF-based adaptive envelope [...] Read more.

When operating under harsh condition (e.g., time-varying speed and load, large shocks), the vibration signals of rolling element bearings are always manifested as low signal noise ratio, non-stationary statistical parameters, which cause difficulties for current diagnostic methods. As such, an IMF-based adaptive envelope order analysis (IMF-AEOA) is proposed for bearing fault detection under such conditions. This approach is established through combining the ensemble empirical mode decomposition (EEMD), envelope order tracking and fault sensitive analysis. In this scheme, EEMD provides an effective way to adaptively decompose the raw vibration signal into IMFs with different frequency bands. The envelope order tracking is further employed to transform the envelope of each IMF to angular domain to eliminate the spectral smearing induced by speed variation, which makes the bearing characteristic frequencies more clear and discernible in the envelope order spectrum. Finally, a fault sensitive matrix is established to select the optimal IMF containing the richest diagnostic information for final decision making. The effectiveness of IMF-AEOA is validated by simulated signal and experimental data from locomotive bearings. The result shows that IMF-AEOA could accurately identify both single and multiple faults of bearing even under time-varying rotating speed and large extraneous shocks. Full article

(This article belongs to the Section Physical Sensors)

▼ Show Figures

13 pages, 1438 KiB

Open AccessArticle

Estimation of Nitrogen Vertical Distribution by Bi-Directional Canopy Reflectance in Winter Wheat

by Wenjiang Huang^1,*

, Qinying Yang^1,2, Ruiliang Pu³ and Shaoyuan Yang^1,2

¹ Key Laboratory of Digital Earth Science, Institute of Remote Sensing and Digital Earth, Chinese Academy of Sciences, Beijing 100094, China

² Key Laboratory of Intelligent Computing & Signal Processing, Ministry of Education, Anhui University, Hefei 230039, China

³ School of Geosciences, University of South Florida, Tampa, FL 33620, USA

Sensors 2014, 14(11), 20347-20359; https://doi.org/10.3390/s141120347 - 28 Oct 2014

Cited by 36 | Viewed by 6153

Abstract

Timely measurement of vertical foliage nitrogen distribution is critical for increasing crop yield and reducing environmental impact. In this study, a novel method with partial least square regression (PLSR) and vegetation indices was developed to determine optimal models for extracting vertical foliage nitrogen [...] Read more.

Timely measurement of vertical foliage nitrogen distribution is critical for increasing crop yield and reducing environmental impact. In this study, a novel method with partial least square regression (PLSR) and vegetation indices was developed to determine optimal models for extracting vertical foliage nitrogen distribution of winter wheat by using bi-directional reflectance distribution function (BRDF) data. The BRDF data were collected from ground-based hyperspectral reflectance measurements recorded at the Xiaotangshan Precision Agriculture Experimental Base in 2003, 2004 and 2007. The view zenith angles (1) at nadir, 40° and 50°; (2) at nadir, 30° and 40°; and (3) at nadir, 20° and 30° were selected as optical view angles to estimate foliage nitrogen density (FND) at an upper, middle and bottom layer, respectively. For each layer, three optimal PLSR analysis models with FND as a dependent variable and two vegetation indices (nitrogen reflectance index (NRI), normalized pigment chlorophyll index (NPCI) or a combination of NRI and NPCI) at corresponding angles as explanatory variables were established. The experimental results from an independent model verification demonstrated that the PLSR analysis models with the combination of NRI and NPCI as the explanatory variables were the most accurate in estimating FND for each layer. The coefficients of determination (R²) of this model between upper layer-, middle layer- and bottom layer-derived and laboratory-measured foliage nitrogen density were 0.7335, 0.7336, 0.6746, respectively. Full article

(This article belongs to the Section Remote Sensors)

▼ Show Figures

12 pages, 2826 KiB

Open AccessArticle

Sol-Gel Zinc Oxide Humidity Sensors Integrated with a Ring Oscillator Circuit On-a-Chip

by Ming-Zhi Yang¹, Ching-Liang Dai^1,* and Chyan-Chyi Wu²

¹ Department of Mechanical Engineering, National Chung Hsing University, Taichung 402, Taiwan

² Department of Mechanical and Electro-Mechanical Engineering, Tamkang University, Tamsui 251, Taiwan

Sensors 2014, 14(11), 20360-20371; https://doi.org/10.3390/s141120360 - 28 Oct 2014

Cited by 27 | Viewed by 6716

Abstract

The study develops an integrated humidity microsensor fabricated using the commercial 0.18 μm complementary metal oxide semiconductor (CMOS) process. The integrated humidity sensor consists of a humidity sensor and a ring oscillator circuit on-a-chip. The humidity sensor is composed of a sensitive film [...] Read more.

The study develops an integrated humidity microsensor fabricated using the commercial 0.18 μm complementary metal oxide semiconductor (CMOS) process. The integrated humidity sensor consists of a humidity sensor and a ring oscillator circuit on-a-chip. The humidity sensor is composed of a sensitive film and branch interdigitated electrodes. The sensitive film is zinc oxide prepared by sol-gel method. After completion of the CMOS process, the sensor requires a post-process to remove the sacrificial oxide layer and to coat the zinc oxide film on the interdigitated electrodes. The capacitance of the sensor changes when the sensitive film adsorbs water vapor. The circuit is used to convert the capacitance of the humidity sensor into the oscillation frequency output. Experimental results show that the output frequency of the sensor changes from 84.3 to 73.4 MHz at 30 °C as the humidity increases 40 to 90%RH. Full article

(This article belongs to the Section Chemical Sensors)

▼ Show Figures

10 pages, 1666 KiB

Open AccessArticle

Temperature Modulation of a Catalytic Gas Sensor

by Eike Brauns¹, Eva Morsbach², Sebastian Kunz², Marcus Baeumer² and Walter Lang^1,*

¹ Institute for Microsensors, -Actuators and -Systems (IMSAS), University of Bremen, Otto-Hahn-Allee NW1, Bremen 28359, Germany

² Institute of Applied and Physical Chemistry (IAPC), University of Bremen, Leobener Str. NW2, Bremen 28359, Germany

Sensors 2014, 14(11), 20372-20381; https://doi.org/10.3390/s141120372 - 29 Oct 2014

Cited by 19 | Viewed by 6106

Abstract

The use of catalytic gas sensors usually offers low selectivity, only based on their different sensitivities for various gases due to their different heats of reaction. Furthermore, the identification of the gas present is not possible, which leads to possible misinterpretation of the [...] Read more.

The use of catalytic gas sensors usually offers low selectivity, only based on their different sensitivities for various gases due to their different heats of reaction. Furthermore, the identification of the gas present is not possible, which leads to possible misinterpretation of the sensor signals. The use of micro-machined catalytic gas sensors offers great advantages regarding the response time, which allows advanced analysis of the sensor response. By using temperature modulation, additional information about the gas characteristics can be measured and drift effects caused by material shifting or environmental temperature changes can be avoided. In this work a miniaturized catalytic gas sensor which offers a very short response time (<150 ms) was developed. Operation with modulated temperature allows analysis of the signal spectrum with advanced information content, based on the Arrhenius approach. Therefore, a high-precise electronic device was developed, since theory shows that harmonics induced by the electronics must be avoided to generate a comprehensible signal. Full article

(This article belongs to the Section Chemical Sensors)

▼ Show Figures

18 pages, 668 KiB

Open AccessArticle

Missing Data Imputation of Solar Radiation Data under Different Atmospheric Conditions

by Concepción Crespo Turrado¹, María Del Carmen Meizoso López², Fernando Sánchez Lasheras^3,*

, Benigno Antonio Rodríguez Gómez², José Luis Calvo Rollé²

and Francisco Javier de Cos Juez⁴

¹ Maintenance Department, University of Oviedo, San Francisco 3, Oviedo 3307, Spain

² Departamento de Ingeniería Industrial, University of A Coruña, A Coruña 15405, Spain

³ Department of Construction and Manufacturing Engineering, University of Oviedo, Gijón 33204, Spain

⁴ Project Management Area, Mining Department, University of Oviedo, Oviedo 33004, Spain

Sensors 2014, 14(11), 20382-20399; https://doi.org/10.3390/s141120382 - 29 Oct 2014

Cited by 72 | Viewed by 7823

Abstract

Global solar broadband irradiance on a planar surface is measured at weather stations by pyranometers. In the case of the present research, solar radiation values from nine meteorological stations of the MeteoGalicia real-time observational network, captured and stored every ten minutes, are considered. [...] Read more.

Global solar broadband irradiance on a planar surface is measured at weather stations by pyranometers. In the case of the present research, solar radiation values from nine meteorological stations of the MeteoGalicia real-time observational network, captured and stored every ten minutes, are considered. In this kind of record, the lack of data and/or the presence of wrong values adversely affects any time series study. Consequently, when this occurs, a data imputation process must be performed in order to replace missing data with estimated values. This paper aims to evaluate the multivariate imputation of ten-minute scale data by means of the chained equations method (MICE). This method allows the network itself to impute the missing or wrong data of a solar radiation sensor, by using either all or just a group of the measurements of the remaining sensors. Very good results have been obtained with the MICE method in comparison with other methods employed in this field such as Inverse Distance Weighting (IDW) and Multiple Linear Regression (MLR). The average RMSE value of the predictions for the MICE algorithm was 13.37% while that for the MLR it was 28.19%, and 31.68% for the IDW. Full article

(This article belongs to the Section Physical Sensors)

▼ Show Figures

19 pages, 4042 KiB

Open AccessArticle

Robust Object Segmentation Using a Multi-Layer Laser Scanner

by Beomseong Kim^1,†, Baehoon Choi^1,†, Minkyun Yoo^2,†, Hyunju Kim^2,† and Euntai Kim^1,*

¹ Electrical and Electronic Engineering Department, Yonsei University, Seoul 120-749, Korea

² Advanced Driver Assistance System Recognition Development Team, Hyundai Motors, Gyeonggi 445-706, Korea

^† These authors contributed equally to this work.

Sensors 2014, 14(11), 20400-20418; https://doi.org/10.3390/s141120400 - 29 Oct 2014

Cited by 14 | Viewed by 7189

Abstract

The major problem in an advanced driver assistance system (ADAS) is the proper use of sensor measurements and recognition of the surrounding environment. To this end, there are several types of sensors to consider, one of which is the laser scanner. In this [...] Read more.

The major problem in an advanced driver assistance system (ADAS) is the proper use of sensor measurements and recognition of the surrounding environment. To this end, there are several types of sensors to consider, one of which is the laser scanner. In this paper, we propose a method to segment the measurement of the surrounding environment as obtained by a multi-layer laser scanner. In the segmentation, a full set of measurements is decomposed into several segments, each representing a single object. Sometimes a ghost is detected due to the ground or fog, and the ghost has to be eliminated to ensure the stability of the system. The proposed method is implemented on a real vehicle, and its performance is tested in a real-world environment. The experiments show that the proposed method demonstrates good performance in many real-life situations. Full article

(This article belongs to the Special Issue Positioning and Tracking Sensors and Technologies in Road Transport)

▼ Show Figures

20 pages, 1192 KiB

Open AccessArticle

Design and Application of Quadrature Compensation Patterns in Bulk Silicon Micro-Gyroscopes

by Yunfang Ni^1,2, Hongsheng Li^1,2,* and Libin Huang^1,2

¹ School of Instrument Science and Engineering, Southeast University, Nanjing 210096, China

² Key Laboratory of Micro-Inertial Instrument and Advanced Navigation Technology of Ministry of Education, Southeast University, Nanjing 210096, China

Sensors 2014, 14(11), 20419-20438; https://doi.org/10.3390/s141120419 - 29 Oct 2014

Cited by 15 | Viewed by 6457

Abstract

This paper focuses on the detailed design issues of a peculiar quadrature reduction method named system stiffness matrix diagonalization, whose key technology is the design and application of quadrature compensation patterns. For bulk silicon micro-gyroscopes, a complete design and application case was presented. [...] Read more.

This paper focuses on the detailed design issues of a peculiar quadrature reduction method named system stiffness matrix diagonalization, whose key technology is the design and application of quadrature compensation patterns. For bulk silicon micro-gyroscopes, a complete design and application case was presented. The compensation principle was described first. In the mechanical design, four types of basic structure units were presented to obtain the basic compensation function. A novel layout design was proposed to eliminate the additional disturbing static forces and torques. Parameter optimization was carried out to maximize the available compensation capability in a limited layout area. Two types of voltage loading methods were presented. Their influences on the sense mode dynamics were analyzed. The proposed design was applied on a dual-mass silicon micro-gyroscope developed in our laboratory. The theoretical compensation capability of a quadrature equivalent angular rate no more than 412 °/s was designed. In experiments, an actual quadrature equivalent angular rate of 357 °/s was compensated successfully. The actual compensation voltages were a little larger than the theoretical ones. The correctness of the design and the theoretical analyses was verified. They can be commonly used in planar linear vibratory silicon micro-gyroscopes for quadrature compensation purpose. Full article

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

▼ Show Figures

12 pages, 4701 KiB

Open AccessArticle

An Efficient Algorithm Embedded in an Ultrasonic Visualization Technique for Damage Inspection Using the AE Sensor Excitation Method

by Yaolu Liu¹, Riu Goda², Kiyoshi Samata³, Atsushi Kanda⁴, Ning Hu^1,2,*

, Jianyu Zhang¹, Huiming Ning¹ and Liangke Wu¹

¹ College of Aerospace Engineering, Chongqing University, Chongqing 400044, China

² Department of Mechanical Engineering, Chiba University, Chiba 263-8522, Japan

³ JAL Engineering Co. Ltd., Haneda Airport Ota, Tokyo 144-0041, Japan

⁴ Japan Aerospace Exploration Agency, Osawa Mitaka, Tokyo 181-0015, Japan

Sensors 2014, 14(11), 20439-20450; https://doi.org/10.3390/s141120439 - 29 Oct 2014

Cited by 10 | Viewed by 5520

Abstract

To improve the reliability of a Lamb wave visualization technique and to obtain more information about structural damages (e.g., size and shape), we put forward a new signal processing algorithm to identify damage more clearly in an inspection region. Since the kinetic energy [...] Read more.

To improve the reliability of a Lamb wave visualization technique and to obtain more information about structural damages (e.g., size and shape), we put forward a new signal processing algorithm to identify damage more clearly in an inspection region. Since the kinetic energy of material particles in a damaged area would suddenly change when ultrasonic waves encounter the damage, the new algorithm embedded in the wave visualization technique is aimed at monitoring the kinetic energy variations of all points in an inspection region to construct a damage diagnostic image. To validate the new algorithm, three kinds of surface damages on the center of aluminum plates, including two non-penetrative slits with different depths and a circular dent, were experimentally inspected. From the experimental results, it can be found that the new algorithm can remarkably enhance the quality of the diagnostic image, especially for some minor defects. Full article

(This article belongs to the Special Issue Acoustic Waveguide Sensors)

▼ Show Figures

17 pages, 6823 KiB

Open AccessArticle

Spatial and Temporal Analysis on the Distribution of Active Radio-Frequency Identification (RFID) Tracking Accuracy with the Kriging Method

by Xin Liu^1,*

, Jeremy Shannon², Howard Voun², Martijn Truijens², Hung-Lin Chi¹ and Xiangyu Wang^1,3

¹ Australasian Joint Research Centre for Building Information Modelling, Curtin University, Bentley WA 6102, Australia

² Woodside Energy Ltd., Perth 6000, Australia

³ Department of Housing and Interior Design, Kyung Hee University, Seoul 130-171, Korea

Sensors 2014, 14(11), 20451-20467; https://doi.org/10.3390/s141120451 - 29 Oct 2014

Cited by 16 | Viewed by 6141

Abstract

Radio frequency identification (RFID) technology has already been applied in a number of areas to facilitate the tracking process. However, the insufficient tracking accuracy of RFID is one of the problems that impedes its wider application. Previous studies focus on examining the accuracy [...] Read more.

Radio frequency identification (RFID) technology has already been applied in a number of areas to facilitate the tracking process. However, the insufficient tracking accuracy of RFID is one of the problems that impedes its wider application. Previous studies focus on examining the accuracy of discrete points RFID, thereby leaving the tracking accuracy of the areas between the observed points unpredictable. In this study, spatial and temporal analysis is applied to interpolate the continuous distribution of RFID tracking accuracy based on the Kriging method. An implementation trial has been conducted in the loading and docking area in front of a warehouse to validate this approach. The results show that the weak signal area can be easily identified by the approach developed in the study. The optimum distance between two RFID readers and the effect of the sudden removal of readers are also presented by analysing the spatial and temporal variation of RFID tracking accuracy. This study reveals the correlation between the testing time and the stability of RFID tracking accuracy. Experimental results show that the proposed approach can be used to assist the RFID system setup process to increase tracking accuracy. Full article

(This article belongs to the Section Sensor Networks)

▼ Show Figures

12 pages, 2471 KiB

Open AccessArticle

New Approach to a Practical Quartz Crystal Microbalance Sensor Utilizing an Inkjet Printing System

by Yusuke Fuchiwaki^1,2,*, Masato Tanaka¹, Yoji Makita¹ and Toshihiko Ooie¹

¹ Health Research Institute, National Institute of Advanced Industrial Science and Technology (AIST), 2217-14, Hayashi-cho, Takamatsu, Kagawa 761-0395, Japan

² CEA-LETI, MINATEC, Campus, 17 rue des Martyrs, 38054 Grenoble Cedex 9, France

Sensors 2014, 14(11), 20468-20479; https://doi.org/10.3390/s141120468 - 30 Oct 2014

Cited by 9 | Viewed by 6524

Abstract

The present work demonstrates a valuable approach to developing quartz crystal microbalance (QCM) sensor units inexpensively for reliable determination of analytes. This QCM sensor unit is constructed by inkjet printing equipment utilizing background noise removal techniques. Inkjet printing equipment was chosen as an [...] Read more.

The present work demonstrates a valuable approach to developing quartz crystal microbalance (QCM) sensor units inexpensively for reliable determination of analytes. This QCM sensor unit is constructed by inkjet printing equipment utilizing background noise removal techniques. Inkjet printing equipment was chosen as an alternative to an injection pump in conventional flow-mode systems to facilitate the commercial applicability of these practical devices. The results demonstrate minimization of fluctuations from external influences, determination of antigen-antibody interactions in an inkjet deposition, and quantification of C-reactive protein in the range of 50–1000 ng∙mL⁻¹. We thus demonstrate a marketable application of an inexpensive and easily available QCM sensor system. Full article

(This article belongs to the Special Issue Mass-Sensitive Sensors Based on Biomimetic Recognition)

▼ Show Figures

20 pages, 3249 KiB

Open AccessArticle

Analysis of SnO₂|WO₃ Heterocontact Properties during the Detection of Hydrogen Sulphide

by Patrycja Suchorska-Woźniak^*

, Olga Rac

, Marta Fiedot

and Helena Teterycz

Wroclaw University of Technology, Faculty of Microsystem Electronics and Photonics, Janiszewskiego 11/17, Wroclaw 50-372, Poland

Sensors 2014, 14(11), 20480-20499; https://doi.org/10.3390/s141120480 - 30 Oct 2014

Cited by 16 | Viewed by 5901

Abstract

The main objective of the paper was the analysis of the properties of SnO₂|WO₃ heterocontact as well as the determination of its response to 50 ppm of hydrogen sulphide. It was noticed that the sensitivity of the sensor being tested [...] Read more.

The main objective of the paper was the analysis of the properties of SnO₂|WO₃ heterocontact as well as the determination of its response to 50 ppm of hydrogen sulphide. It was noticed that the sensitivity of the sensor being tested to hydrogen sulphide depended significantly on the polarization direction. When its parameters were compared with those of sensors the gas-sensitive layer of which was made only from one type of metal oxide, a high impact of the heterocontact on the electric charge transport was noticed. The value of the activation energy of the electric conductivity is clearly dependent on the polarization direction. A mechanism of physicochemical processes occurring in a planar sensor with a heterocontact was suggested, and three areas differing in the width of depleted layer, where the inter-phase boundary of SnO₂|WO₃ had the most essential impact on the parameters of the sensor being tested, were distinguished and described. Full article

(This article belongs to the Section Chemical Sensors)

▼ Show Figures

19 pages, 749 KiB

Open AccessArticle

Memetic Algorithm-Based Multi-Objective Coverage Optimization for Wireless Sensor Networks

by Zhi Chen^1,2,3,*, Shuai Li¹ and Wenjing Yue⁴

¹ College of Computer, Nanjing University of Posts and Telecommunications, No.9, Wenyuan Road, Yadong new District, Nanjing 210023, China

² Jiangsu High Technology Research Key Laboratory for Wireless Sensor Networks, No.66, New Mofan Road, Gulou District, Nanjing 210003, China

³ State Key Laboratory for Novel Software Technology, Nanjing University, No.163, Xianlin Road, Qixia District, Nanjing 210023, China

⁴ Key Lab of Broadband Wireless Communication and Sensor Network Technology, Ministry of Education, No.66, New Mofan Road, Gulou District, Nanjing 210003, China

Sensors 2014, 14(11), 20500-20518; https://doi.org/10.3390/s141120500 - 30 Oct 2014

Cited by 27 | Viewed by 6068

Abstract

Maintaining effective coverage and extending the network lifetime as much as possible has become one of the most critical issues in the coverage of WSNs. In this paper, we propose a multi-objective coverage optimization algorithm for WSNs, namely MOCADMA, which models the coverage [...] Read more.

Maintaining effective coverage and extending the network lifetime as much as possible has become one of the most critical issues in the coverage of WSNs. In this paper, we propose a multi-objective coverage optimization algorithm for WSNs, namely MOCADMA, which models the coverage control of WSNs as the multi-objective optimization problem. MOCADMA uses a memetic algorithm with a dynamic local search strategy to optimize the coverage of WSNs and achieve the objectives such as high network coverage, effective node utilization and more residual energy. In MOCADMA, the alternative solutions are represented as the chromosomes in matrix form, and the optimal solutions are selected through numerous iterations of the evolution process, including selection, crossover, mutation, local enhancement, and fitness evaluation. The experiment and evaluation results show MOCADMA can have good capabilities in maintaining the sensing coverage, achieve higher network coverage while improving the energy efficiency and effectively prolonging the network lifetime, and have a significant improvement over some existing algorithms. Full article

(This article belongs to the Section Sensor Networks)

▼ Show Figures

14 pages, 2122 KiB

Open AccessArticle

Fabrication and Evaluation of a Micro(Bio)Sensor Array Chip for Multiple Parallel Measurements of Important Cell Biomarkers

by Roy M. Pemberton^1,*, Timothy Cox^2,†, Rachel Tuffin², Guido A. Drago³, John Griffiths⁴, Robin Pittson⁵, Graham Johnson⁴, Jinsheng Xu¹, Ian C. Sage², Rhodri Davies², Simon K. Jackson^1,‡, Gerry Kenna⁶, Richard Luxton⁷ and John P. Hart^1,*

¹ Centre for Research in Biosciences, Faculty of Health and Life Sciences, University of the West of England, Bristol, BS16 1QY, UK

² QinetiQ Ltd., Malvern Technology Centre, Malvern, WR14 3PS, UK

³ Applied Enzyme Technology Ltd., Monmouth House, Mamhilad Park, Pontypool NP4 OHZ, UK

⁴ Uniscan Instruments Ltd., Sigma House, Burlow Rd., Buxton, Derbyshire SK17 9JB, UK

⁵ Gwent Electronic Materials Ltd., Monmouth House, Mamhilad Park, Pontypool NP4 OHZ, UK

⁶ AstraZeneca R&D, Alderley Park, Macclesfield, SK10 4TF, UK

⁷ Institute of Biosensing Technology, University of the West of England, Bristol, BS16 1QY, UK

^† Current address: Institute of Biosensing Technology, University of the West of England, Bristol, BS16 1QY, UK

^‡ Current address: Centre for Research in Translational Biomedicine, School of Biomedical and Biological Sciences, University of Plymouth, Plymouth PL4 8AA, UK

Sensors 2014, 14(11), 20519-20532; https://doi.org/10.3390/s141120519 - 30 Oct 2014

Cited by 31 | Viewed by 8944

Abstract

This report describes the design and development of an integrated electrochemical cell culture monitoring system, based on enzyme-biosensors and chemical sensors, for monitoring indicators of mammalian cell metabolic status. MEMS technology was used to fabricate a microwell-format silicon platform including a thermometer, onto [...] Read more.

This report describes the design and development of an integrated electrochemical cell culture monitoring system, based on enzyme-biosensors and chemical sensors, for monitoring indicators of mammalian cell metabolic status. MEMS technology was used to fabricate a microwell-format silicon platform including a thermometer, onto which chemical sensors (pH, O₂) and screen-printed biosensors (glucose, lactate), were grafted/deposited. Microwells were formed over the fabricated sensors to give 5-well sensor strips which were interfaced with a multipotentiostat via a bespoke connector box interface. The operation of each sensor/biosensor type was examined individually, and examples of operating devices in five microwells in parallel, in either potentiometric (pH sensing) or amperometric (glucose biosensing) mode are shown. The performance characteristics of the sensors/biosensors indicate that the system could readily be applied to cell culture/toxicity studies. Full article

(This article belongs to the Special Issue Printed Sensors)

▼ Show Figures

10 pages, 1427 KiB

Open AccessArticle

A Three-Dimensional Microdisplacement Sensing System Based on MEMS Bulk-Silicon Technology

by Junjie Wu^1,2, Lihua Lei², Xin Chen^1,*, Xiaoyu Cai², Yuan Li² and Tao Han¹

¹ School of Electronic Information and Electrical Engineering, Shanghai Jiao Tong University, No. 800, Dongchuan Road, Shanghai 200240, China

² Shanghai Institute of Measurement and Testing Technology, National Center of Measurement and Testing for East China, National Center of Testing Technology, No. 1500, Zhangheng Road, Shanghai 201203, China

Sensors 2014, 14(11), 20533-20542; https://doi.org/10.3390/s141120533 - 30 Oct 2014

Cited by 4 | Viewed by 6173

Abstract

For the dimensional measurement and characterization of microsized and nanosized components, a three-dimensional microdisplacement sensing system was developed using the piezoresistive effect in silicon. The sensor was fabricated using microelectromechanical system bulk-silicon technology, and it was validated using the finite element method. A [...] Read more.

For the dimensional measurement and characterization of microsized and nanosized components, a three-dimensional microdisplacement sensing system was developed using the piezoresistive effect in silicon. The sensor was fabricated using microelectromechanical system bulk-silicon technology, and it was validated using the finite element method. A precise data acquisition circuit with an accuracy of 20 μV was designed to obtain weak voltage signals. By calibration, the sensing system was shown to have a sensitivity of 17.29 mV/μm and 4.59 mV/μm in the axial and lateral directions, respectively; the nonlinearity in these directions was 0.8% and 1.0% full scale, respectively. A full range of 4.6 μm was achieved in the axial direction. Results of a resolution test indicated that the sensing system had a resolution of 5 nm in the axial direction and 10 nm in the lateral direction. Full article

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

▼ Show Figures

19 pages, 3908 KiB

Open AccessArticle

Toward Smart Aerospace Structures: Design of a Piezoelectric Sensor and Its Analog Interface for Flaw Detection

by Hamza Boukabache^1,2,*, Christophe Escriba^2,3 and Jean-Yves Fourniols^2,3

¹ ECA Group, Aerospace Division, 5 Rue Paul Mesple, Toulouse 31100, France

² CNRS, LAAS, 7 Avenue du Colonel Roche, Toulouse F-31400, France

³ Univ de Toulouse, INSA, LAAS, Toulouse F-31400, France

Sensors 2014, 14(11), 20543-20561; https://doi.org/10.3390/s141120543 - 31 Oct 2014

Cited by 32 | Viewed by 12853

Abstract

Structural health monitoring using noninvasive methods is one of the major challenges that aerospace manufacturers face in this decade. Our work in this field focuses on the development and the system integration of millimetric piezoelectric sensors/ actuators to generate and measure specific guided [...] Read more.

Structural health monitoring using noninvasive methods is one of the major challenges that aerospace manufacturers face in this decade. Our work in this field focuses on the development and the system integration of millimetric piezoelectric sensors/ actuators to generate and measure specific guided waves. The aim of the application is to detect mechanical flaws on complex composite and alloy structures to quantify efficiently the global structures’ reliability. The study begins by a physical and analytical analysis of a piezoelectric patch. To preserve the structure’s integrity, the transducers are directly pasted onto the surface which leads to a critical issue concerning the interfacing layer. In order to improve the reliability and mitigate the influence of the interfacing layer, the global equations of piezoelectricity are coupled with a load transfer model. Thus we can determine precisely the shear strain developed on the surface of the structure. To exploit the generated signal, a high precision analog charge amplifier coupled to a double T notch filter were designed and scaled. Finally, a novel joined time-frequency analysis based on a wavelet decomposition algorithm is used to extract relevant structures signatures. Finally, this paper provides examples of application on aircraft structure specimens and the feasibility of the system is thus demonstrated. Full article

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

▼ Show Figures

27 pages, 1659 KiB

Open AccessArticle

Wireless Sensor Networks for Heritage Object Deformation Detection and Tracking Algorithm

by Zhijun Xie^1,*, Guangyan Huang², Roozbeh Zarei³, Jing He³, Yanchun Zhang³ and Hongwu Ye⁴

¹ Department of Information Science and Engineering, Ningbo University, Ningbo 315021, China

² School of Information Technology, Deakin University, Melbourne 3125, Australia

³ College of Engineering and Science, Victoria University, Melbourne 3011, Australia

⁴ Zhejiang Fashion Institute of Technology, P. R. 315021, China

Sensors 2014, 14(11), 20562-20588; https://doi.org/10.3390/s141120562 - 31 Oct 2014

Cited by 4 | Viewed by 6197

Abstract

Deformation is the direct cause of heritage object collapse. It is significant to monitor and signal the early warnings of the deformation of heritage objects. However, traditional heritage object monitoring methods only roughly monitor a simple-shaped heritage object as a whole, but cannot [...] Read more.

Deformation is the direct cause of heritage object collapse. It is significant to monitor and signal the early warnings of the deformation of heritage objects. However, traditional heritage object monitoring methods only roughly monitor a simple-shaped heritage object as a whole, but cannot monitor complicated heritage objects, which may have a large number of surfaces inside and outside. Wireless sensor networks, comprising many small-sized, low-cost, low-power intelligent sensor nodes, are more useful to detect the deformation of every small part of the heritage objects. Wireless sensor networks need an effective mechanism to reduce both the communication costs and energy consumption in order to monitor the heritage objects in real time. In this paper, we provide an effective heritage object deformation detection and tracking method using wireless sensor networks (EffeHDDT). In EffeHDDT, we discover a connected core set of sensor nodes to reduce the communication cost for transmitting and collecting the data of the sensor networks. Particularly, we propose a heritage object boundary detecting and tracking mechanism. Both theoretical analysis and experimental results demonstrate that our EffeHDDT method outperforms the existing methods in terms of network traffic and the precision of the deformation detection. Full article

(This article belongs to the Special Issue Sensors for Cultural Heritage Diagnostics)

▼ Show Figures

13 pages, 1812 KiB

Open AccessArticle

Automatic Classification of the Sub-Techniques (Gears) Used in Cross-Country Ski Skating Employing a Mobile Phone

by Thomas Stöggl^1,2,*, Anders Holst^3,4, Arndt Jonasson³, Erik Andersson², Tobias Wunsch¹, Christer Norström³ and Hans-Christer Holmberg^2,5

¹ Department of Sport Science and Kinesiology, University of Salzburg, Hallein/Rif 5400, Austria

² Swedish Winter Sports Research Centre, Department of Health Sciences, Mid Sweden University, Östersund 83140, Sweden

³ Swedish Institute of Computer Science, Kista 16440, Sweden

⁴ School of Computer Science and Communication, Royal Institute of Technology, Stockholm 10044, Sweden

⁵ Swedish Olympic Committee, Stockholm 11433, Sweden

Sensors 2014, 14(11), 20589-20601; https://doi.org/10.3390/s141120589 - 31 Oct 2014

Cited by 35 | Viewed by 7797

Abstract

The purpose of the current study was to develop and validate an automatic algorithm for classification of cross-country (XC) ski-skating gears (G) using Smartphone accelerometer data. Eleven XC skiers (seven men, four women) with regional-to-international levels of performance carried out roller skiing trials [...] Read more.

The purpose of the current study was to develop and validate an automatic algorithm for classification of cross-country (XC) ski-skating gears (G) using Smartphone accelerometer data. Eleven XC skiers (seven men, four women) with regional-to-international levels of performance carried out roller skiing trials on a treadmill using fixed gears (G2left, G2right, G3, G4left, G4right) and a 950-m trial using different speeds and inclines, applying gears and sides as they normally would. Gear classification by the Smartphone (on the chest) and based on video recordings were compared. Formachine-learning, a collective database was compared to individual data. The Smartphone application identified the trials with fixed gears correctly in all cases. In the 950-m trial, participants executed 140 ± 22 cycles as assessed by video analysis, with the automatic Smartphone application giving a similar value. Based on collective data, gears were identified correctly 86.0% ± 8.9% of the time, a value that rose to 90.3% ± 4.1% (P < 0.01) with machine learning from individual data. Classification was most often incorrect during transition between gears, especially to or from G3. Identification was most often correct for skiers who made relatively few transitions between gears. The accuracy of the automatic procedure for identifying G2left, G2right, G3, G4left and G4right was 96%, 90%, 81%, 88% and 94%, respectively. The algorithm identified gears correctly 100% of the time when a single gear was used and 90% of the time when different gears were employed during a variable protocol. This algorithm could be improved with respect to identification of transitions between gears or the side employed within a given gear. Full article

(This article belongs to the Section Physical Sensors)

▼ Show Figures

22 pages, 2856 KiB

Open AccessArticle

Monitoring and Control Interface Based on Virtual Sensors

by Ricardo F. Escobar¹

, Manuel Adam-Medina¹, Carlos D. García-Beltrán¹

, Víctor H. Olivares-Peregrino^1,*, David Juárez-Romero² and Gerardo V. Guerrero-Ramírez¹

¹ Centro Nacional de Investigación y Desarrollo Tecnológico, Tecnológico Nacional de México, Int. Internado Palmira S/N, Palmira, C.P. 62490 Cuernavaca, Morelos, Mexico

² Centro de Investigación en Ingeniería y Ciencias Aplicadas, Universidad Autónoma del Estado de Morelos, Av. Universidad 1001, Col. Chamilpa, C.P. 62209 Cuernavaca, Morelos, Mexico

Sensors 2014, 14(11), 20645-20666; https://doi.org/10.3390/s141120645 - 31 Oct 2014

Cited by 3 | Viewed by 6290

Abstract

In this article, a toolbox based on a monitoring and control interface (MCI) is presented and applied in a heat exchanger. The MCI was programed in order to realize sensor fault detection and isolation and fault tolerance using virtual sensors. The virtual sensors [...] Read more.

In this article, a toolbox based on a monitoring and control interface (MCI) is presented and applied in a heat exchanger. The MCI was programed in order to realize sensor fault detection and isolation and fault tolerance using virtual sensors. The virtual sensors were designed from model-based high-gain observers. To develop the control task, different kinds of control laws were included in the monitoring and control interface. These control laws are PID, MPC and a non-linear model-based control law. The MCI helps to maintain the heat exchanger under operation, even if a temperature outlet sensor fault occurs; in the case of outlet temperature sensor failure, the MCI will display an alarm. The monitoring and control interface is used as a practical tool to support electronic engineering students with heat transfer and control concepts to be applied in a double-pipe heat exchanger pilot plant. The method aims to teach the students through the observation and manipulation of the main variables of the process and by the interaction with the monitoring and control interface (MCI) developed in LabVIEW^©. The MCI provides the electronic engineering students with the knowledge of heat exchanger behavior, since the interface is provided with a thermodynamic model that approximates the temperatures and the physical properties of the fluid (density and heat capacity). An advantage of the interface is the easy manipulation of the actuator for an automatic or manual operation. Another advantage of the monitoring and control interface is that all algorithms can be manipulated and modified by the users. Full article

(This article belongs to the Section Physical Sensors)

▼ Show Figures

20 pages, 2891 KiB

Open AccessArticle

A Novel Dog-Bone Oscillating AFM Probe with Thermal Actuation and Piezoresistive Detection

by Zhuang Xiong^1,*, Estelle Mairiaux², Benjamin Walter², Marc Faucher², Lionel Buchaillot² and Bernard Legrand^2,‡

¹ Institute of Electronic Engineering, China Academy of Engineering Physics, Mianyang 621999, China

² Institut d'Electronique, de Microélectronique et de Nanotechnologie—IEMN CNRS UMR8520, NAM6 group, Villeneuve d'Ascq 59650, France

^‡ Bernard Legrand is now with LAAS CNRS UPR8001, NBS group, Toulouse 31031, France.

Sensors 2014, 14(11), 20667-20686; https://doi.org/10.3390/s141120667 - 31 Oct 2014

Cited by 6 | Viewed by 7237

Abstract

In order to effectively increase the resonance frequency and the quality factor of atomic force microscope (AFM) probes, a novel oscillating probe based on a dog-bone shaped MEMS resonator was conceived, designed, fabricated and evaluated. The novel probe with 400 μm in length, [...] Read more.

In order to effectively increase the resonance frequency and the quality factor of atomic force microscope (AFM) probes, a novel oscillating probe based on a dog-bone shaped MEMS resonator was conceived, designed, fabricated and evaluated. The novel probe with 400 μm in length, 100 μm in width and 5 μm in thickness was enabled to feature MHz resonance frequencies with integrated thermal actuation and piezoresistive detection. Standard silicon micromachining was employed. Both electrical and optical measurements were carried out in air. The resonance frequency and the quality factor of the novel probe were measured to be 5.4 MHz and 4000 respectively, which are much higher than those (about several hundreds of kHz) of commonly used cantilever probes. The probe was mounted onto a commercial AFM set-up through a dedicated probe-holder and circuit board. Topographic images of patterned resist samples were obtained. It is expected that the resonance frequency and the measurement bandwidth of such probes will be further increased by a proper downscaling, thus leading to a significant increase in the scanning speed capability of AFM instruments. Full article

(This article belongs to the Section Physical Sensors)

▼ Show Figures

15 pages, 1717 KiB

Open AccessArticle

Simulation of the Recharging Method of Implantable Biosensors Based on a Wearable Incoherent Light Source

by Yong Song^1,*, Qun Hao^1,*, Xianyue Kong¹, Lanxin Hu¹, Jie Cao¹ and Tianxin Gao²

¹ School of Opto-Electronics, Beijing Institute of Technology, Beijing 100081, China

² School of Life Science, Beijing Institute of Technology, Beijing 100081, China

Sensors 2014, 14(11), 20687-20701; https://doi.org/10.3390/s141120687 - 3 Nov 2014

Cited by 10 | Viewed by 6066

Abstract

Recharging implantable electronics from the outside of the human body is very important for applications such as implantable biosensors and other implantable electronics. In this paper, a recharging method for implantable biosensors based on a wearable incoherent light source has been proposed and [...] Read more.

Recharging implantable electronics from the outside of the human body is very important for applications such as implantable biosensors and other implantable electronics. In this paper, a recharging method for implantable biosensors based on a wearable incoherent light source has been proposed and simulated. Firstly, we develop a model of the incoherent light source and a multi-layer model of skin tissue. Secondly, the recharging processes of the proposed method have been simulated and tested experimentally, whereby some important conclusions have been reached. Our results indicate that the proposed method will offer a convenient, safe and low-cost recharging method for implantable biosensors, which should promote the application of implantable electronics. Full article

(This article belongs to the Special Issue Miniaturized Wireless Biosensors)

▼ Show Figures

11 pages, 1401 KiB

Open AccessArticle

A Novel Wireless and Temperature-Compensated SAW Vibration Sensor

by Wen Wang^*, Xufeng Xue, Yangqing Huang and Xinlu Liu

State Key Laboratory of Acoustics, Institute of Acoustic, Chinese Academy of Science, No.21, BeiSiHuan West Road, Beijing 100190, China

Sensors 2014, 14(11), 20702-20712; https://doi.org/10.3390/s141120702 - 3 Nov 2014

Cited by 30 | Viewed by 8232

Abstract

A novel wireless and passive surface acoustic wave (SAW) based temperature-compensated vibration sensor utilizing a flexible Y-cut quartz cantilever beam with a relatively substantial proof mass and two one-port resonators is developed. One resonator acts as the sensing device adjacent to the clamped [...] Read more.

A novel wireless and passive surface acoustic wave (SAW) based temperature-compensated vibration sensor utilizing a flexible Y-cut quartz cantilever beam with a relatively substantial proof mass and two one-port resonators is developed. One resonator acts as the sensing device adjacent to the clamped end for maximum strain sensitivity, and the other one is used as the reference located on clamped end for temperature compensation for vibration sensor through the differential approach. Vibration directed to the proof mass flex the cantilever, inducing relative changes in the acoustic propagation characteristics of the SAW travelling along the sensing device, and generated output signal varies in frequency as a function of vibration. A theoretical mode using the Rayleigh method was established to determine the optimal dimensions of the cantilever beam. Coupling of Modes (COM) model was used to extract the optimal design parameters of the SAW devices prior to fabrication. The performance of the developed SAW sensor attached to an antenna towards applied vibration was evaluated wirelessly by using the precise vibration table, programmable incubator chamber, and reader unit. High vibration sensitivity of ~10.4 kHz/g, good temperature stability, and excellent linearity were observed in the wireless measurements. Full article

(This article belongs to the Special Issue Acoustic Waveguide Sensors)

▼ Show Figures

23 pages, 1100 KiB

Open AccessArticle

An SVM-Based Classifier for Estimating the State of Various Rotating Components in Agro-Industrial Machinery with a Vibration Signal Acquired from a Single Point on the Machine Chassis

by Ruben Ruiz-Gonzalez^1,*, Jaime Gomez-Gil¹

, Francisco Javier Gomez-Gil² and Víctor Martínez-Martínez¹

¹ Department of Signal Theory, Communications and Telematics Engineering, University of Valladolid, Valladolid 47011, Spain

² Department of Electromechanical Engineering, University of Burgos, Burgos 09006, Spain

Sensors 2014, 14(11), 20713-20735; https://doi.org/10.3390/s141120713 - 3 Nov 2014

Cited by 60 | Viewed by 14044

Abstract

The goal of this article is to assess the feasibility of estimating the state of various rotating components in agro-industrial machinery by employing just one vibration signal acquired from a single point on the machine chassis. To do so, a Support Vector Machine [...] Read more.

The goal of this article is to assess the feasibility of estimating the state of various rotating components in agro-industrial machinery by employing just one vibration signal acquired from a single point on the machine chassis. To do so, a Support Vector Machine (SVM)-based system is employed. Experimental tests evaluated this system by acquiring vibration data from a single point of an agricultural harvester, while varying several of its working conditions. The whole process included two major steps. Initially, the vibration data were preprocessed through twelve feature extraction algorithms, after which the Exhaustive Search method selected the most suitable features. Secondly, the SVM-based system accuracy was evaluated by using Leave-One-Out cross-validation, with the selected features as the input data. The results of this study provide evidence that (i) accurate estimation of the status of various rotating components in agro-industrial machinery is possible by processing the vibration signal acquired from a single point on the machine structure; (ii) the vibration signal can be acquired with a uniaxial accelerometer, the orientation of which does not significantly affect the classification accuracy; and, (iii) when using an SVM classifier, an 85% mean cross-validation accuracy can be reached, which only requires a maximum of seven features as its input, and no significant improvements are noted between the use of either nonlinear or linear kernels. Full article

(This article belongs to the Special Issue Agriculture and Forestry: Sensors, Technologies and Procedures)

▼ Show Figures

17 pages, 2239 KiB

Open AccessArticle

A Target Model Construction Algorithm for Robust Real-Time Mean-Shift Tracking

by Yoo-Joo Choi and Yong-Goo Kim^*

Department of Newmedia, Korean German Institute of Technology, 99, Hwagok-ro 61-gil, Gangseo-gu, Seoul 157-930, Korea

Sensors 2014, 14(11), 20736-20752; https://doi.org/10.3390/s141120736 - 3 Nov 2014

Cited by 6 | Viewed by 5223

Abstract

Mean-shift tracking has gained more interests, nowadays, aided by its feasibility of real-time and reliable tracker implementation. In order to reduce background clutter interference to mean-shift object tracking, this paper proposes a novel indicator function generation method. The proposed method takes advantage of [...] Read more.

Mean-shift tracking has gained more interests, nowadays, aided by its feasibility of real-time and reliable tracker implementation. In order to reduce background clutter interference to mean-shift object tracking, this paper proposes a novel indicator function generation method. The proposed method takes advantage of two ‘a priori’ knowledge elements, which are inherent to a kernel support for initializing a target model. Based on the assured background labels, a gradient-based label propagation is performed, resulting in a number of objects differentiated from the background. Then the proposed region growing scheme picks up one largest target object near the center of the kernel support. The grown object region constitutes the proposed indicator function and this allows an exact target model construction for robust mean-shift tracking. Simulation results demonstrate the proposed exact target model could significantly enhance the robustness as well as the accuracy of mean-shift object tracking. Full article

(This article belongs to the Section Physical Sensors)

▼ Show Figures

26 pages, 767 KiB

Open AccessArticle

Adaptive Activity and Environment Recognition for Mobile Phones

by Jussi Parviainen^1,*, Jayaprasad Bojja¹, Jussi Collin¹, Jussi Leppänen² and Antti Eronen²

¹ Department of Pervasive Computing, Tampere University of Technology, FI-33101 Tampere, Finland

² Nokia Technologies, FI-33721 Tampere, Finland

Sensors 2014, 14(11), 20753-20778; https://doi.org/10.3390/s141120753 - 3 Nov 2014

Cited by 22 | Viewed by 6343

Abstract

In this paper, an adaptive activity and environment recognition algorithm running on a mobile phone is presented. The algorithm makes inferences based on sensor and radio receiver data provided by the phone. A wide set of features that can be extracted from these [...] Read more.

In this paper, an adaptive activity and environment recognition algorithm running on a mobile phone is presented. The algorithm makes inferences based on sensor and radio receiver data provided by the phone. A wide set of features that can be extracted from these data sources were investigated, and a Bayesian maximum a posteriori classifier was used for classifying between several user activities and environments. The accuracy of the method was evaluated on a dataset collected in a real-life trial. In addition, comparison to other state-of-the-art classifiers, namely support vector machines and decision trees, was performed. To make the system adaptive for individual user characteristics, an adaptation algorithm for context model parameters was designed. Moreover, a confidence measure for the classification correctness was designed. The proposed adaptation algorithm and confidence measure were evaluated on a second dataset obtained from another real-life trial, where the users were requested to provide binary feedback on the classification correctness. The results show that the proposed adaptation algorithm is effective at improving the classification accuracy. Full article

(This article belongs to the Special Issue HCI In Smart Environments)

▼ Show Figures

21 pages, 2252 KiB

Open AccessArticle

Design of a Lossless Image Compression System for Video Capsule Endoscopy and Its Performance in In-Vivo Trials

by Tareq H. Khan and Khan A. Wahid^*

Department of Electrical and Computer Engineering, University of Saskatchewan, Saskatoon, SK S7N5A9, Canada

Sensors 2014, 14(11), 20779-20799; https://doi.org/10.3390/s141120779 - 4 Nov 2014

Cited by 30 | Viewed by 7735

Abstract

In this paper, a new low complexity and lossless image compression system for capsule endoscopy (CE) is presented. The compressor consists of a low-cost YEF color space converter and variable-length predictive with a combination of Golomb-Rice and unary encoding. All these components have [...] Read more.

In this paper, a new low complexity and lossless image compression system for capsule endoscopy (CE) is presented. The compressor consists of a low-cost YEF color space converter and variable-length predictive with a combination of Golomb-Rice and unary encoding. All these components have been heavily optimized for low-power and low-cost and lossless in nature. As a result, the entire compression system does not incur any loss of image information. Unlike transform based algorithms, the compressor can be interfaced with commercial image sensors which send pixel data in raster-scan fashion that eliminates the need of having large buffer memory. The compression algorithm is capable to work with white light imaging (WLI) and narrow band imaging (NBI) with average compression ratio of 78% and 84% respectively. Finally, a complete capsule endoscopy system is developed on a single, low-power, 65-nm field programmable gate arrays (FPGA) chip. The prototype is developed using circular PCBs having a diameter of 16 mm. Several in-vivo and ex-vivo trials using pig's intestine have been conducted using the prototype to validate the performance of the proposed lossless compression algorithm. The results show that, compared with all other existing works, the proposed algorithm offers a solution to wireless capsule endoscopy with lossless and yet acceptable level of compression. Full article

(This article belongs to the Section Physical Sensors)

▼ Show Figures

25 pages, 1140 KiB

Open AccessArticle

Human Mobility Monitoring in Very Low Resolution Visual Sensor Network

by Nyan Bo Bo^1,*, Francis Deboeverie¹, Mohamed Eldib¹, Junzhi Guan¹, Xingzhe Xie¹

, Jorge Niño¹, Dirk Van Haerenborgh¹, Maarten Slembrouck¹, Samuel Van de Velde², Heidi Steendam², Peter Veelaert¹, Richard Kleihorst¹, Hamid Aghajan^1,3 and Wilfried Philips¹

¹ Image Processing and Interpretation, Gent University/iMinds, Gent 9000, Belgium

² Digital Communications, Gent University/iMinds, Gent 9000, Belgium

³ Ambient Intelligence Research Lab, David Packard Building, Stanford, CA 94305, USA

Sensors 2014, 14(11), 20800-20824; https://doi.org/10.3390/s141120800 - 4 Nov 2014

Cited by 21 | Viewed by 7785

Abstract

This paper proposes an automated system for monitoring mobility patterns using a network of very low resolution visual sensors (30 × 30 pixels). The use of very low resolution sensors reduces privacy concern, cost, computation requirement and power consumption. The core of our [...] Read more.

This paper proposes an automated system for monitoring mobility patterns using a network of very low resolution visual sensors (30 × 30 pixels). The use of very low resolution sensors reduces privacy concern, cost, computation requirement and power consumption. The core of our proposed system is a robust people tracker that uses low resolution videos provided by the visual sensor network. The distributed processing architecture of our tracking system allows all image processing tasks to be done on the digital signal controller in each visual sensor. In this paper, we experimentally show that reliable tracking of people is possible using very low resolution imagery. We also compare the performance of our tracker against a state-of-the-art tracking method and show that our method outperforms. Moreover, the mobility statistics of tracks such as total distance traveled and average speed derived from trajectories are compared with those derived from ground truth given by Ultra-Wide Band sensors. The results of this comparison show that the trajectories from our system are accurate enough to obtain useful mobility statistics. Full article

(This article belongs to the Special Issue Ambient Assisted Living (AAL): Sensors, Architectures and Applications)

▼ Show Figures

23 pages, 1194 KiB

Open AccessArticle

Using Smart Phone Sensors to Detect Transportation Modes

by Hao Xia^*, Yanyou Qiao, Jun Jian and Yuanfei Chang

The Institute of Remote Sensing and Digital Earth, No.20 Datun Road, Chaoyang District, Beijing 100101, China

Sensors 2014, 14(11), 20843-20865; https://doi.org/10.3390/s141120843 - 4 Nov 2014

Cited by 69 | Viewed by 9202

Abstract

The proliferation of mobile smart devices has led to a rapid increase of location-based services, many of which are amassing large datasets of user trajectory information. Unfortunately, current trajectory information is not yet sufficiently rich to support classification of user transportation modes. In [...] Read more.

The proliferation of mobile smart devices has led to a rapid increase of location-based services, many of which are amassing large datasets of user trajectory information. Unfortunately, current trajectory information is not yet sufficiently rich to support classification of user transportation modes. In this paper, we propose a method that employs both the Global Positioning System and accelerometer data from smart devices to classify user outdoor transportation modes. The classified modes include walking, bicycling, and motorized transport, in addition to the motionless (stationary) state, for which we provide new depth analysis. In our classification, stationary mode has two sub-modes: stay (remaining in the same place for a prolonged time period; e.g., in a parked vehicle) and wait (remaining at a location for a short period; e.g., waiting at a red traffic light). These two sub-modes present different semantics for data mining applications. We use support vector machines with parameters that are optimized for pattern recognition. In addition, we employ ant colony optimization to reduce the dimension of features and analyze their relative importance. The resulting classification system achieves an accuracy rate of 96.31% when applied to a dataset obtained from 18 mobile users. Full article

(This article belongs to the Special Issue Positioning and Tracking Sensors and Technologies in Road Transport)

▼ Show Figures

16 pages, 1732 KiB

Open AccessArticle

Accuracy Assessment of the Integration of GNSS and a MEMS IMU in a Terrestrial Platform

by Sergio Madeira^1,*,†, Wenlin Yan^2,†, Luísa Bastos^2,3,† and José A. Gonçalves^2,3,†

¹ University of Trás-os-Montes e Alto Douro, Vila Real 5000-801, Portugal; INESC-TEC - Technology and Science, Rua Dr. Roberto Frias, 4200-465 Porto, Portugal

² Department of Geosciences Environment and Spatial Planning, Faculty of Science, University of Porto, Rua Campo Alegre 687, Porto 4169-007, Portugal

³ CIIMAR/CIMAR, University of Porto, Rua dos Bragas 289, Porto 4050-123, Portugal

^† These authors contributed equally to this work.

Sensors 2014, 14(11), 20866-20881; https://doi.org/10.3390/s141120866 - 4 Nov 2014

Cited by 3 | Viewed by 6126

Abstract

MEMS Inertial Measurement Units are available at low cost and can replace expensive units in mobile mapping platforms which need direct georeferencing. This is done through the integration with GNSS measurements in order to achieve a continuous positioning solution and to obtain orientation [...] Read more.

MEMS Inertial Measurement Units are available at low cost and can replace expensive units in mobile mapping platforms which need direct georeferencing. This is done through the integration with GNSS measurements in order to achieve a continuous positioning solution and to obtain orientation angles. This paper presents the results of the assessment of the accuracy of a system that integrates GNSS and a MEMS IMU in a terrestrial platform. We describe the methodology used and the tests realized where the accuracy of the positions and orientation parameters were assessed using an independent photogrammetric technique employing cameras that integrate the mobile mapping system developed by the authors. Results for the accuracy of attitude angles and coordinates show that accuracies better than a decimeter in positions, and under a degree in angles, can be achieved even considering that the terrestrial platform is operating in less than favorable environments. Full article

(This article belongs to the Section Physical Sensors)

▼ Show Figures

28 pages, 8873 KiB

Open AccessArticle

Sensor Fusion of Cameras and a Laser for City-Scale 3D Reconstruction

by Yunsu Bok, Dong-Geol Choi and In So Kweon^*

Robotics and Computer Vision Lab., KAIST, 291 Daehak-ro, Yuseong-gu, Daejeon 305-701, Korea

Sensors 2014, 14(11), 20882-20909; https://doi.org/10.3390/s141120882 - 4 Nov 2014

Cited by 11 | Viewed by 7843

Abstract

This paper presents a sensor fusion system of cameras and a 2D laser sensorfor large-scale 3D reconstruction. The proposed system is designed to capture data on afast-moving ground vehicle. The system consists of six cameras and one 2D laser sensor,and they are synchronized [...] Read more.

This paper presents a sensor fusion system of cameras and a 2D laser sensorfor large-scale 3D reconstruction. The proposed system is designed to capture data on afast-moving ground vehicle. The system consists of six cameras and one 2D laser sensor,and they are synchronized by a hardware trigger. Reconstruction of 3D structures is doneby estimating frame-by-frame motion and accumulating vertical laser scans, as in previousworks. However, our approach does not assume near 2D motion, but estimates free motion(including absolute scale) in 3D space using both laser data and image features. In orderto avoid the degeneration associated with typical three-point algorithms, we present a newalgorithm that selects 3D points from two frames captured by multiple cameras. The problemof error accumulation is solved by loop closing, not by GPS. The experimental resultsshow that the estimated path is successfully overlaid on the satellite images, such that thereconstruction result is very accurate. Full article

(This article belongs to the Section Sensor Networks)

▼ Show Figures

20 pages, 2036 KiB

Open AccessArticle

A Real-Time Localization System for an Endoscopic Capsule Using Magnetic Sensors

by Duc Minh Pham^* and Syed Mahfuzul Aziz

School of Engineering, University of South Australia, Mawson Lakes, South Australia 5095, Australia

Sensors 2014, 14(11), 20910-20929; https://doi.org/10.3390/s141120910 - 5 Nov 2014

Cited by 66 | Viewed by 8527

Abstract

Magnetic sensing technology offers an attractive alternative for in vivo tracking with much better performance than RF and ultrasound technologies. In this paper, an efficient in vivo magnetic tracking system is presented. The proposed system is intended to localize an endoscopic capsule which [...] Read more.

Magnetic sensing technology offers an attractive alternative for in vivo tracking with much better performance than RF and ultrasound technologies. In this paper, an efficient in vivo magnetic tracking system is presented. The proposed system is intended to localize an endoscopic capsule which delivers biomarkers around specific locations of the gastrointestinal (GI) tract. For efficiently localizing a magnetic marker inside the capsule, a mathematical model has been developed for the magnetic field around a cylindrical magnet and used with a localization algorithm that provides minimum error and fast computation. The proposed tracking system has much reduced complexity compared to the ones reported in the literature to date. Laboratory tests and in vivo animal trials have demonstrated the suitability of the proposed system for tracking a magnetic marker with expected accuracy. Full article

(This article belongs to the Special Issue Biomedical Sensors and Systems)

▼ Show Figures

10 pages, 1274 KiB

Open AccessArticle

Temperature-Independent Fiber Inclinometer Based on Orthogonally Polarized Modes Coupling Using a Polarization-Maintaining Fiber Bragg Grating

by Dan Su^1,*, Xueguang Qiao¹, Hangzhou Yang¹, Qiangzhou Rong¹, Zhengyuan Bai², Yupeng Wang¹ and Zhongyao Feng¹

¹ School of Physics, Northwest University, Xi'an 710069, China

² Key Laboratory of Material for High Power Lasers, Shanghai Institute of Optics and Fine Mechanics, Chinese Academy of Sciences, Shanghai 201800, China

Sensors 2014, 14(11), 20930-20939; https://doi.org/10.3390/s141120930 - 5 Nov 2014

Cited by 9 | Viewed by 5803

Abstract

A reflection fiber inclinometer is proposed and experimentally demonstrated based on two linearly polarized (LP) modes coupling. The configuration consists of a section of polarization-maintaining fiber (PMF) containing a fiber Bragg grating (FBG) splicing with single mode fiber (SMF). Bending the PMF in [...] Read more.

A reflection fiber inclinometer is proposed and experimentally demonstrated based on two linearly polarized (LP) modes coupling. The configuration consists of a section of polarization-maintaining fiber (PMF) containing a fiber Bragg grating (FBG) splicing with single mode fiber (SMF). Bending the PMF in the upstream of FBG can induce an additional birefringence of PMF, which results in the intensity changes of two LP modes owing to orthogonal polarization coupling. The experimental results represent that the device shows different bending responses at the angle range from 0° to 40°and from 64° to 88°, respectively. Moreover, the temperature change just shifts the wavelengths of LP modes reflected and does not influence their intensities, which effectively avoid the temperature cross-sensitivity and make it a good candidate for measuring inclinometer and temperature simultaneously. Full article

(This article belongs to the Section Physical Sensors)

▼ Show Figures

23 pages, 1409 KiB

Open AccessArticle

Service-Oriented Node Scheduling Scheme for Wireless Sensor Networks Using Markov Random Field Model

by Hongju Cheng^1,2,*, Zhihuang Su¹, Jaime Lloret³

and Guolong Chen^1,4

¹ College of Mathematics and Computer Science, Fuzhou University, Fuzhou 350108, China

² Department of Computer Science, The University of Alabama, Tuscaloosa, AL 35401, USA

³ Instituto de Investigación Para la Gestión Integrada de Zonas Costeras, Universidad Politécnica de Valencia, C/ Paranimf nº 1, Grao de Gandia, Gandia, Valencia 46730, Spain

⁴ Fujian Provincial Key Laboratory of Network Computing and Intelligent Information Processing, Fuzhou University, Fuzhou 350108, China

Sensors 2014, 14(11), 20940-20962; https://doi.org/10.3390/s141120940 - 6 Nov 2014

Cited by 9 | Viewed by 5428

Abstract

Future wireless sensor networks are expected to provide various sensing services and energy efficiency is one of the most important criterions. The node scheduling strategy aims to increase network lifetime by selecting a set of sensor nodes to provide the required sensing services [...] Read more.

Future wireless sensor networks are expected to provide various sensing services and energy efficiency is one of the most important criterions. The node scheduling strategy aims to increase network lifetime by selecting a set of sensor nodes to provide the required sensing services in a periodic manner. In this paper, we are concerned with the service-oriented node scheduling problem to provide multiple sensing services while maximizing the network lifetime. We firstly introduce how to model the data correlation for different services by using Markov Random Field (MRF) model. Secondly, we formulate the service-oriented node scheduling issue into three different problems, namely, the multi-service data denoising problem which aims at minimizing the noise level of sensed data, the representative node selection problem concerning with selecting a number of active nodes while determining the services they provide, and the multi-service node scheduling problem which aims at maximizing the network lifetime. Thirdly, we propose a Multi-service Data Denoising (MDD) algorithm, a novel multi-service Representative node Selection and service Determination (RSD) algorithm, and a novel MRF-based Multi-service Node Scheduling (MMNS) scheme to solve the above three problems respectively. Finally, extensive experiments demonstrate that the proposed scheme efficiently extends the network lifetime. Full article

(This article belongs to the Section Sensor Networks)

▼ Show Figures

12 pages, 1052 KiB

Open AccessArticle

Portable Solid Phase Micro-Extraction Coupled with Ion Mobility Spectrometry System for On-Site Analysis of Chemical Warfare Agents and Simulants in Water Samples

by Liu Yang^1,*,†, Qiang Han^2,†, Shuya Cao¹, Jie Yang¹, Junchao Yang¹ and Mingyu Ding^2,*

¹ State Key Laboratory of NBC Protection for Civilian, Beijing 102205, China

² Beijing Key Laboratory for Microanalytical Methods and Instrumentation, Department of Chemistry, Tsinghua University, Beijing 100084, China

^† These authors contributed equally to this study and share first authorship.

Sensors 2014, 14(11), 20963-20974; https://doi.org/10.3390/s141120963 - 6 Nov 2014

Cited by 16 | Viewed by 6127

Abstract

On-site analysis is an efficient approach to facilitate analysis at the location of the system under investigation as it can result in more accurate, more precise and quickly available analytical data. In our work, a novel self-made thermal desorption based interface was fabricated [...] Read more.

On-site analysis is an efficient approach to facilitate analysis at the location of the system under investigation as it can result in more accurate, more precise and quickly available analytical data. In our work, a novel self-made thermal desorption based interface was fabricated to couple solid-phase microextraction with ion mobility spectrometry for on-site water analysis. The portable interface can be connected with the front-end of an ion mobility spectrometer directly without other modifications. The analytical performance was evaluated via the extraction of chemical warfare agents and simulants in water samples. Several parameters including ionic strength and extraction time have been investigated in detail. The application of the developed method afforded satisfactory recoveries ranging from 72.9% to 114.4% when applied to the analysis of real water samples. Full article

(This article belongs to the Section Chemical Sensors)

▼ Show Figures

25 pages, 7521 KiB

Open AccessArticle

Measuring Snow Liquid Water Content with Low-Cost GPS Receivers

by Franziska Koch^1,*, Monika Prasch¹, Lino Schmid², Jürg Schweizer²

and Wolfram Mauser¹

¹ Department of Geography, Ludwig-Maximilians-Universität München, Luisenstr. 37, Munich 80333, Germany

² WSL Institute for Snow and Avalanche Research SLF, Flüelastr. 11, 7260 Davos Dorf, Switzerland

Sensors 2014, 14(11), 20975-20999; https://doi.org/10.3390/s141120975 - 6 Nov 2014

Cited by 57 | Viewed by 10411

Abstract

The amount of liquid water in snow characterizes the wetness of a snowpack. Its temporal evolution plays an important role for wet-snow avalanche prediction, as well as the onset of meltwater release and water availability estimations within a river basin. However, it is [...] Read more.

The amount of liquid water in snow characterizes the wetness of a snowpack. Its temporal evolution plays an important role for wet-snow avalanche prediction, as well as the onset of meltwater release and water availability estimations within a river basin. However, it is still a challenge and a not yet satisfyingly solved issue to measure the liquid water content (LWC) in snow with conventional in situ and remote sensing techniques. We propose a new approach based on the attenuation of microwave radiation in the L-band emitted by the satellites of the Global Positioning System (GPS). For this purpose, we performed a continuous low-cost GPS measurement experiment at the Weissfluhjoch test site in Switzerland, during the snow melt period in 2013. As a measure of signal strength, we analyzed the carrier-to-noise power density ratio (C/N₀) and developed a procedure to normalize these data. The bulk volumetric LWC was determined based on assumptions for attenuation, reflection and refraction of radiation in wet snow. The onset of melt, as well as daily melt-freeze cycles were clearly detected. The temporal evolution of the LWC was closely related to the meteorological and snow-hydrological data. Due to its non-destructive setup, its cost-efficiency and global availability, this approach has the potential to be implemented in distributed sensor networks for avalanche prediction or basin-wide melt onset measurements. Full article

(This article belongs to the Section Remote Sensors)

▼ Show Figures

23 pages, 457 KiB

Open AccessArticle

Localisation of an Unknown Number of Land Mines Using a Network of Vapour Detectors

by Hiba Haj Chhadé^1,2,*, Fahed Abdallah¹, Imad Mougharbel², Amadou Gning³, Simon Julier³ and Lyudmila Mihaylova⁴

¹ University of Technology of Compiègne, rue Roger Couttolenc, Compiègne 60200, France

² Lebanese University, Beirut, Lebanon

³ Department of Computer Science, University College London, WC1E 6BT London, UK

⁴ University of Sheffield, S1 3JD Sheffield, UK

Sensors 2014, 14(11), 21000-21022; https://doi.org/10.3390/s141121000 - 6 Nov 2014

Cited by 2 | Viewed by 6027

Abstract

We consider the problem of localising an unknown number of land mines usingconcentration information provided by a wireless sensor network. A number of vapoursensors/detectors, deployed in the region of interest, are able to detect the concentrationof the explosive vapours, emanating from buried land [...] Read more.

We consider the problem of localising an unknown number of land mines usingconcentration information provided by a wireless sensor network. A number of vapoursensors/detectors, deployed in the region of interest, are able to detect the concentrationof the explosive vapours, emanating from buried land mines. The collected data iscommunicated to a fusion centre. Using a model for the transport of the explosive chemicalsin the air, we determine the unknown number of sources using a Principal ComponentAnalysis (PCA)-based technique. We also formulate the inverse problem of determiningthe positions and emission rates of the land mines using concentration measurementsprovided by the wireless sensor network. We present a solution for this problem basedon a probabilistic Bayesian technique using a Markov chain Monte Carlo sampling scheme,and we compare it to the least squares optimisation approach. Experiments conducted onsimulated data show the effectiveness of the proposed approach. Full article

(This article belongs to the Section Chemical Sensors)

▼ Show Figures

22 pages, 396 KiB

Open AccessArticle

A Provably-Secure ECC-Based Authentication Scheme for Wireless Sensor Networks

by Junghyun Nam¹, Moonseong Kim², Juryon Paik³, Youngsook Lee⁴ and Dongho Won^3,*

¹ Department of Computer Engineering, Konkuk University, 268 Chungwondaero, Chungju, Chungcheongbukdo 380-701, Korea

² Information Management Division, Korean Intellectual Property Office, 189 Cheongsaro, Daejeon 302-701, Korea

³ Department of Computer Engineering, Sungkyunkwan University, 2066 Seoburo, Suwon, Gyeonggido 440-746, Korea

⁴ Department of Cyber Investigation Police, Howon University, 64 3-gil, Gunsan, Jeonrabukdo 573-718, Korea

Sensors 2014, 14(11), 21023-21044; https://doi.org/10.3390/s141121023 - 6 Nov 2014

Cited by 53 | Viewed by 7115

Abstract

A smart-card-based user authentication scheme for wireless sensor networks (in short, a SUA-WSN scheme) is designed to restrict access to the sensor data only to users who are in possession of both a smart card and the corresponding password. While a significant number [...] Read more.

A smart-card-based user authentication scheme for wireless sensor networks (in short, a SUA-WSN scheme) is designed to restrict access to the sensor data only to users who are in possession of both a smart card and the corresponding password. While a significant number of SUA-WSN schemes have been suggested in recent years, their intended security properties lack formal definitions and proofs in a widely-accepted model. One consequence is that SUA-WSN schemes insecure against various attacks have proliferated. In this paper, we devise a security model for the analysis of SUA-WSN schemes by extending the widely-accepted model of Bellare, Pointcheval and Rogaway (2000). Our model provides formal definitions of authenticated key exchange and user anonymity while capturing side-channel attacks, as well as other common attacks. We also propose a new SUA-WSN scheme based on elliptic curve cryptography (ECC), and prove its security properties in our extended model. To the best of our knowledge, our proposed scheme is the first SUA-WSN scheme that provably achieves both authenticated key exchange and user anonymity. Our scheme is also computationally competitive with other ECC-based (non-provably secure) schemes. Full article

(This article belongs to the Section Sensor Networks)

▼ Show Figures

20 pages, 5341 KiB

Open AccessArticle

Odometry for Ground Moving Agents by Optic Flow Recorded with Optical Mouse Chips

by Hansjürgen Dahmen^* and Hanspeter A. Mallot

Cognitive Neuroscience, University of Tübingen, Auf der Morgenstelle 28, Tübingen 72076, Germany

Sensors 2014, 14(11), 21045-21064; https://doi.org/10.3390/s141121045 - 6 Nov 2014

Cited by 11 | Viewed by 7922

Abstract

Optical mouse chips—equipped with adequate lenses—can serve as small, light, precise, fast, and cheap motion sensors monitoring optic flow induced by self motion of an agent in a contrasted environment. We present a device that extracts self motion parameters exclusively from flow in [...] Read more.

Optical mouse chips—equipped with adequate lenses—can serve as small, light, precise, fast, and cheap motion sensors monitoring optic flow induced by self motion of an agent in a contrasted environment. We present a device that extracts self motion parameters exclusively from flow in eight mouse sensors. Four pairs of sensors with opposite azimuth are mounted on a sensor head, each individual sensor looking down with \(-\)45\(^{\circ}\) elevation. The head is mounted on a carriage and is moved at constant height above a textured planar ground. The calibration procedure and tests on the precision of self motion estimates are reported. Full article

(This article belongs to the Special Issue Optical Gyroscopes and Navigation Systems)

▼ Show Figures

11 pages, 341 KiB

Open AccessArticle

A Coumarin-Based Fluorescent Probe as a Central Nervous System Disease Biomarker

by Ann-Chee Yap¹, Ummi Affah Mahamad², Shen-Yang Lim², Hae-Jo Kim³ and Yeun-Mun Choo^1,*

¹ Department of Chemistry, Faculty of Science, University of Malaya, Kuala Lumpur 50603, Malaysia

² Department of Medicine, Faculty of Medicine, University of Malaya, Kuala Lumpur 50603, Malaysia

³ Department of Chemistry, Hankuk University of Foreign Studies, Yongin 449-791, Korea

Sensors 2014, 14(11), 21140-21150; https://doi.org/10.3390/s141121140 - 10 Nov 2014

Cited by 4 | Viewed by 6288

Abstract

Homocysteine and methylmalonic acid are important biomarkers for diseases associated with an impaired central nervous system (CNS). A new chemoassay utilizing coumarin-based fluorescent probe 1 to detect the levels of homocysteine is successfully implemented using Parkinson’s disease (PD) patients’ blood serum. In addition, [...] Read more.

Homocysteine and methylmalonic acid are important biomarkers for diseases associated with an impaired central nervous system (CNS). A new chemoassay utilizing coumarin-based fluorescent probe 1 to detect the levels of homocysteine is successfully implemented using Parkinson’s disease (PD) patients’ blood serum. In addition, a rapid identification of homocysteine and methylmalonic acid levels in blood serum of PD patients was also performed using the liquid chromatography-mass spectrometry (LC-MS). The results obtained from both analyses were in agreement. The new chemoassay utilizing coumarin-based fluorescent probe 1 offers a cost- and time-effective method to identify the biomarkers in CNS patients. Full article

(This article belongs to the Special Issue Advances in Optical Biosensors)

▼ Show Figures

23 pages, 1344 KiB

Open AccessArticle

VibeComm: Radio-Free Wireless Communication for Smart Devices Using Vibration

by Inhwan Hwang, Jungchan Cho and Songhwai Oh^*

Department of Electrical and Computer Engineering and ASRI, Seoul National University, 1 Gwanak-ro, Gwanak-gu, Seoul 151-744, Korea

Sensors 2014, 14(11), 21151-21173; https://doi.org/10.3390/s141121151 - 10 Nov 2014

Cited by 8 | Viewed by 6466

Abstract

This paper proposes VibeComm, a novel communication method for smart devices using a built-in vibrator and accelerometer. The proposed approach is ideal for low-rate off-line communication, and its communication medium is an object on which smart devices are placed, such as tables and [...] Read more.

This paper proposes VibeComm, a novel communication method for smart devices using a built-in vibrator and accelerometer. The proposed approach is ideal for low-rate off-line communication, and its communication medium is an object on which smart devices are placed, such as tables and desks. When more than two smart devices are placed on an object and one device wants to transmit a message to the other devices, the transmitting device generates a sequence of vibrations. The vibrations are propagated through the object on which the devices are placed. The receiving devices analyze their accelerometer readings to decode incoming messages. The proposed method can be the alternative communication method when general types of radio communication methods are not available. VibeComm is implemented on Android smartphones, and a comprehensive set of experiments is conducted to show its feasibility. Full article

(This article belongs to the Section Physical Sensors)

▼ Show Figures

21 pages, 334 KiB

Open AccessArticle

Privacy-Preserving Data Aggregation in Two-Tiered Wireless Sensor Networks with Mobile Nodes

by Yonglei Yao¹, Jingfa Liu² and Neal N. Xiong^3,*

¹ School of Computer and Software, Nanjing University of Information Science & Technology, Nanjing 210044, China

² Jiangsu Engineering Center of Network Monitoring, Nanjing University of Information Science & Technology, Nanjing 210044, China

³ School of Computer Science, Colorado Technical University, Colorado Springs, CO 80907, USA

Sensors 2014, 14(11), 21174-21194; https://doi.org/10.3390/s141121174 - 10 Nov 2014

Cited by 12 | Viewed by 4820

Abstract

Privacy-preserving data aggregation in wireless sensor networks (WSNs) with mobile nodes is a challenging problem, as an accurate aggregation result should be derived in a privacy-preserving manner, under the condition that nodes are mobile and have no pre-specified keys for cryptographic operations. In [...] Read more.

Privacy-preserving data aggregation in wireless sensor networks (WSNs) with mobile nodes is a challenging problem, as an accurate aggregation result should be derived in a privacy-preserving manner, under the condition that nodes are mobile and have no pre-specified keys for cryptographic operations. In this paper, we focus on the SUM aggregation function and propose two privacy-preserving data aggregation protocols for two-tiered sensor networks with mobile nodes: Privacy-preserving Data Aggregation against non-colluded Aggregator and Sink (PDAAS) and Privacy-preserving Data Aggregation against Colluded Aggregator and Sink (PDACAS). Both protocols guarantee that the sink can derive the SUM of all raw sensor data but each sensor’s raw data is kept confidential. In PDAAS, two keyed values are used, one shared with the sink and the other shared with the aggregator. PDAAS can protect the privacy of sensed data against external eavesdroppers, compromised sensor nodes, the aggregator or the sink, but fails if the aggregator and the sink collude. In PDACAS, multiple keyed values are used in data perturbation, which are not shared with the aggregator or the sink. PDACAS can protect the privacy of sensor nodes even the aggregator and the sink collude, at the cost of a little more overhead than PDAAS. Thorough analysis and experiments are conducted, which confirm the efficacy and efficiency of both schemes. Full article

(This article belongs to the Section Sensor Networks)

▼ Show Figures

18 pages, 327 KiB

Open AccessArticle

Constrained State Estimation for Individual Localization in Wireless Body Sensor Networks

by Xiaoxue Feng^1,*, Hichem Snoussi², Yan Liang¹ and Lianmeng Jiao¹

¹ School of Automation, Northwestern Polytechnical University, Xi'an 710072, China

² Institute of Charles Delaunay, University of Technology of Troyes, Troyes 10000, France

Sensors 2014, 14(11), 21195-21212; https://doi.org/10.3390/s141121195 - 10 Nov 2014

Cited by 2 | Viewed by 4984

Abstract

Wireless body sensor networks based on ultra-wideband radio have recently received much research attention due to its wide applications in health-care, security, sports and entertainment. Accurate localization is a fundamental problem to realize the development of effective location-aware applications above. In this paper [...] Read more.

Wireless body sensor networks based on ultra-wideband radio have recently received much research attention due to its wide applications in health-care, security, sports and entertainment. Accurate localization is a fundamental problem to realize the development of effective location-aware applications above. In this paper the problem of constrained state estimation for individual localization in wireless body sensor networks is addressed. Priori knowledge about geometry among the on-body nodes as additional constraint is incorporated into the traditional filtering system. The analytical expression of state estimation with linear constraint to exploit the additional information is derived. Furthermore, for nonlinear constraint, first-order and second-order linearizations via Taylor series expansion are proposed to transform the nonlinear constraint to the linear case. Examples between the first-order and second-order nonlinear constrained filters based on interacting multiple model extended kalman filter (IMM-EKF) show that the second-order solution for higher order nonlinearity as present in this paper outperforms the first-order solution, and constrained IMM-EKF obtains superior estimation than IMM-EKF without constraint. Another brownian motion individual localization example also illustrates the effectiveness of constrained nonlinear iterative least square (NILS), which gets better filtering performance than NILS without constraint. Full article

(This article belongs to the Section Sensor Networks)

▼ Show Figures

34 pages, 23053 KiB

Open AccessArticle

iMuseumA: An Agent-Based Context-Aware Intelligent Museum System

by Inmaculada Ayala^*

, Mercedes Amor, Mónica Pinto, Lidia Fuentes and Nadia Gámez

Departamento de Lenguajes y Ciencias de la Computación, Andalucia Tech, Universidad de Málaga, Campus de Teatinos s/n, 29071 Málaga, Spain

Sensors 2014, 14(11), 21213-21246; https://doi.org/10.3390/s141121213 - 10 Nov 2014

Cited by 13 | Viewed by 11434

Abstract

Currently, museums provide their visitors with interactive tour guide applications that can be installed in mobile devices and provide timely tailor-made multimedia information about exhibits on display. In this paper, we argue that mobile devices not only could provide help to visitors, but [...] Read more.

Currently, museums provide their visitors with interactive tour guide applications that can be installed in mobile devices and provide timely tailor-made multimedia information about exhibits on display. In this paper, we argue that mobile devices not only could provide help to visitors, but also to museum staff. Our goal is to integrate, within the same system, multimedia tour guides with the management facilities required by museums. In this paper, we present iMuseumA (intelligent museum with agents), a mobile-based solution to customize visits and perform context-aware management tasks. iMuseumA follows an agent-based approach, which makes it possible to interact easily with the museum environment and make decisions based on its current status. This system is currently deployed in the Museum of Informatics at the Informatics School of the University of Málaga, and its main contributions are: (i) a mobile application that provides management facilities to museum staff by means of sensing and processing environmental data; (ii) providing an integrated solution for visitors, tour guides and museum staff that allows coordination and communication enrichment among different groups of users; (iii) using and benefiting from group communication for heterogeneous groups of users that can be created on demand. Full article

(This article belongs to the Section Sensor Networks)

▼ Show Figures

Graphical abstract

11 pages, 1375 KiB

Open AccessArticle

Fast Human Detection for Intelligent Monitoring Using Surveillance Visible Sensors

by Byoung Chul Ko^*

, Mira Jeong and JaeYeal Nam

Department of Computer Engineering, Keimyung University, Sindang-dong, Dalseo-gu, Daegu 704-701, Korea

Sensors 2014, 14(11), 21247-21257; https://doi.org/10.3390/s141121247 - 11 Nov 2014

Cited by 26 | Viewed by 5250

Abstract

Human detection using visible surveillance sensors is an important and challenging work for intruder detection and safety management. The biggest barrier of real-time human detection is the computational time required for dense image scaling and scanning windows extracted from an entire image. This [...] Read more.

Human detection using visible surveillance sensors is an important and challenging work for intruder detection and safety management. The biggest barrier of real-time human detection is the computational time required for dense image scaling and scanning windows extracted from an entire image. This paper proposes fast human detection by selecting optimal levels of image scale using each level’s adaptive region-of-interest (ROI). To estimate the image-scaling level, we generate a Hough windows map (HWM) and select a few optimal image scales based on the strength of the HWM and the divide-and-conquer algorithm. Furthermore, adaptive ROIs are arranged per image scale to provide a different search area. We employ a cascade random forests classifier to separate candidate windows into human and nonhuman classes. The proposed algorithm has been successfully applied to real-world surveillance video sequences, and its detection accuracy and computational speed show a better performance than those of other related methods. Full article

(This article belongs to the Section Physical Sensors)

▼ Show Figures

23 pages, 489 KiB

Open AccessArticle

The Influence of Random Element Displacement on DOA Estimates Obtained with (Khatri–Rao-)Root-MUSIC

by Veronique Inghelbrecht^1,*, Jo Verhaevert¹

, Tanja Van Hecke¹ and Hendrik Rogier²

¹ Department of Industrial Technology and Construction, Ghent University, Valentin Vaerwyckweg 1 ,9000 Gent, Belgium

² Department of Information Technology, Ghent University, Sint-Pietersnieuwstraat 41, 9000 Gent, Belgium

Sensors 2014, 14(11), 21258-21280; https://doi.org/10.3390/s141121258 - 11 Nov 2014

Cited by 12 | Viewed by 5057

Abstract

Although a wide range of direction of arrival (DOA) estimation algorithms has been described for a diverse range of array configurations, no specific stochastic analysis framework has been established to assess the probability density function of the error on DOA estimates due to [...] Read more.

Although a wide range of direction of arrival (DOA) estimation algorithms has been described for a diverse range of array configurations, no specific stochastic analysis framework has been established to assess the probability density function of the error on DOA estimates due to random errors in the array geometry. Therefore, we propose a stochastic collocation method that relies on a generalized polynomial chaos expansion to connect the statistical distribution of random position errors to the resulting distribution of the DOA estimates. We apply this technique to the conventional root-MUSIC and the Khatri–Rao-root-MUSIC methods. According to Monte-Carlo simulations, this novel approach yields a speedup by a factor of more than 100 in terms of CPU-time for a one-dimensional case and by a factor of 56 for a two-dimensional case. Full article

(This article belongs to the Section Sensor Networks)

▼ Show Figures

35 pages, 1665 KiB

Open AccessArticle

Online Variational Bayesian Filtering-Based Mobile Target Tracking in Wireless Sensor Networks

by Bingpeng Zhou^1,*, Qingchun Chen¹, Tiffany Jing Li² and Pei Xiao³

¹ School of Information Science & Technology, Southwest Jiaotong University, Chengdu 610031, China

² Department of Electrical & Computer Engineering, Lehigh University, Bethlehem, PA 18015, USA

³ The Institute for Communication Systems, University of Surrey, Guildford, Surrey GU2 7XH, UK

Sensors 2014, 14(11), 21281-21315; https://doi.org/10.3390/s141121281 - 11 Nov 2014

Cited by 14 | Viewed by 5964

Abstract

The received signal strength (RSS)-based online tracking for a mobile node in wireless sensor networks (WSNs) is investigated in this paper. Firstly, a multi-layer dynamic Bayesian network (MDBN) is introduced to characterize the target mobility with either directional or undirected movement. In particular, [...] Read more.

The received signal strength (RSS)-based online tracking for a mobile node in wireless sensor networks (WSNs) is investigated in this paper. Firstly, a multi-layer dynamic Bayesian network (MDBN) is introduced to characterize the target mobility with either directional or undirected movement. In particular, it is proposed to employ the Wishart distribution to approximate the time-varying RSS measurement precision’s randomness due to the target movement. It is shown that the proposed MDBN offers a more general analysis model via incorporating the underlying statistical information of both the target movement and observations, which can be utilized to improve the online tracking capability by exploiting the Bayesian statistics. Secondly, based on the MDBN model, a mean-field variational Bayesian filtering (VBF) algorithm is developed to realize the online tracking of a mobile target in the presence of nonlinear observations and time-varying RSS precision, wherein the traditional Bayesian filtering scheme cannot be directly employed. Thirdly, a joint optimization between the real-time velocity and its prior expectation is proposed to enable online velocity tracking in the proposed online tacking scheme. Finally, the associated Bayesian Cramer–Rao Lower Bound (BCRLB) analysis and numerical simulations are conducted. Our analysis unveils that, by exploiting the potential state information via the general MDBN model, the proposed VBF algorithm provides a promising solution to the online tracking of a mobile node in WSNs. In addition, it is shown that the final tracking accuracy linearly scales with its expectation when the RSS measurement precision is time-varying. Full article

(This article belongs to the Section Sensor Networks)

▼ Show Figures

13 pages, 1735 KiB

Open AccessArticle

The Influence of Nanopore Dimensions on the Electrochemical Properties of Nanopore Arrays Studied by Impedance Spectroscopy

by Krishna Kant^1,2, Craig Priest³

, Joe G. Shapter¹ and Dusan Losic^2,*

¹ School of Chemical and Physical Sciences, Flinders University, Bedford Park, Adelaide, SA 5042, Australia

² School of Chemical Engineering, the University of Adelaide, Adelaide, SA 5005, Australia

³ Ian Wark Research Institute, University of South Australia, Mawson Lakes, Adelaide, SA 5095, Australia

Sensors 2014, 14(11), 21316-21328; https://doi.org/10.3390/s141121316 - 11 Nov 2014

Cited by 23 | Viewed by 7853

Abstract

The understanding of the electrochemical properties of nanopores is the key factor for better understanding their performance and applications for nanopore-based sensing devices. In this study, the influence of pore dimensions of nanoporous alumina (NPA) membranes prepared by an anodization process and their [...] Read more.

The understanding of the electrochemical properties of nanopores is the key factor for better understanding their performance and applications for nanopore-based sensing devices. In this study, the influence of pore dimensions of nanoporous alumina (NPA) membranes prepared by an anodization process and their electrochemical properties as a sensing platform using impedance spectroscopy was explored. NPA with four different pore diameters (25 nm, 45 nm and 65 nm) and lengths (5 μm to 20 μm) was used and their electrochemical properties were explored using different concentration of electrolyte solution (NaCl) ranging from 1 to 100 μM. Our results show that the impedance and resistance of nanopores are influenced by the concentration and ion species of electrolytes, while the capacitance is independent of them. It was found that nanopore diameters also have a significant influence on impedance due to changes in the thickness of the double layer inside the pores. Full article

(This article belongs to the Special Issue Nanopore Sensors: Fabrications, Properties and Applications)

▼ Show Figures

29 pages, 4765 KiB

Open AccessArticle

PERFORM: A System for Monitoring, Assessment and Management of Patients with Parkinson’s Disease

by Alexandros T. Tzallas¹, Markos G. Tsipouras¹

, Georgios Rigas¹, Dimitrios G. Tsalikakis², Evaggelos C. Karvounis¹, Maria Chondrogiorgi³, Fotis Psomadellis⁴, Jorge Cancela^5,6, Matteo Pastorino⁵

, María Teresa Arredondo Waldmeyer⁵, Spiros Konitsiotis³ and Dimitrios I. Fotiadis^1,*

¹ Unit of Medical Technology and Intelligent Information Systems, Dept. of Materials Science and Engineering, University of Ioannina, P.O. Box 1186, GR 45110 Ioannina, Greece

² Dept. of Informatics and Telecommunication Engineering, University of Western Macedonia, GR 50100 Kozani, Greece

³ Dept. of Neurology, Medical School, University of Ioannina, GR 45110 Ioannina, Greece

⁴ ANCO S.A. Research and Development Division, 44, Syngrou Avenues, Athens 11742, Greece

⁵ Life Supporting Technologies, Universidad Politécnica de Madrid, Madrid 28040, Spain

⁶ Campus de Excelencia Internacional Campus Moncloa, Universidad Complutense de Madrid - Universidad Politecnica de Madrid, Madrid 28040, Spain

Sensors 2014, 14(11), 21329-21357; https://doi.org/10.3390/s141121329 - 11 Nov 2014

Cited by 137 | Viewed by 19427

Abstract

In this paper, we describe the PERFORM system for the continuous remote monitoring and management of Parkinson’s disease (PD) patients. The PERFORM system is an intelligent closed-loop system that seamlessly integrates a wide range of wearable sensors constantly monitoring several motor signals of [...] Read more.

In this paper, we describe the PERFORM system for the continuous remote monitoring and management of Parkinson’s disease (PD) patients. The PERFORM system is an intelligent closed-loop system that seamlessly integrates a wide range of wearable sensors constantly monitoring several motor signals of the PD patients. Data acquired are pre-processed by advanced knowledge processing methods, integrated by fusion algorithms to allow health professionals to remotely monitor the overall status of the patients, adjust medication schedules and personalize treatment. The information collected by the sensors (accelerometers and gyroscopes) is processed by several classifiers. As a result, it is possible to evaluate and quantify the PD motor symptoms related to end of dose deterioration (tremor, bradykinesia, freezing of gait (FoG)) as well as those related to over-dose concentration (Levodopa-induced dyskinesia (LID)). Based on this information, together with information derived from tests performed with a virtual reality glove and information about the medication and food intake, a patient specific profile can be built. In addition, the patient specific profile with his evaluation during the last week and last month, is compared to understand whether his status is stable, improving or worsening. Based on that, the system analyses whether a medication change is needed—always under medical supervision—and in this case, information about the medication change proposal is sent to the patient. The performance of the system has been evaluated in real life conditions, the accuracy and acceptability of the system by the PD patients and healthcare professionals has been tested, and a comparison with the standard routine clinical evaluation done by the PD patients’ physician has been carried out. The PERFORM system is used by the PD patients and in a simple and safe non-invasive way for long-term record of their motor status, thus offering to the clinician a precise, long-term and objective view of patient’s motor status and drug/food intake. Thus, with the PERFORM system the clinician can remotely receive precise information for the PD patient’s status on previous days and define the optimal therapeutical treatment. Full article

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

▼ Show Figures

17 pages, 1145 KiB

Open AccessArticle

Using Floating Car Data to Analyse the Effects of ITS Measures and Eco-Driving

by Alvaro Garcia-Castro^1,* and Andres Monzon²

¹ Transport Research Centre (TRANSyT), Escuela de Ingenieros de Caminos, Canales y Puertos, Universidad Politécnica de Madrid, Ciudad Universitaria, Madrid 28040, Spain

² Transport- Civil Eng. Department, Escuela de Ingenieros de Caminos, Canales y Puertos, Universidad Politécnica de Madrid, Ciudad Universitaria, Madrid 28040, Spain

Sensors 2014, 14(11), 21358-21374; https://doi.org/10.3390/s141121358 - 11 Nov 2014

Cited by 20 | Viewed by 6740

Abstract

The road transportation sector is responsible for around 25% of total man-made CO₂ emissions worldwide. Considerable efforts are therefore underway to reduce these emissions using several approaches, including improved vehicle technologies, traffic management and changing driving behaviour. Detailed traffic and emissions models [...] Read more.

The road transportation sector is responsible for around 25% of total man-made CO₂ emissions worldwide. Considerable efforts are therefore underway to reduce these emissions using several approaches, including improved vehicle technologies, traffic management and changing driving behaviour. Detailed traffic and emissions models are used extensively to assess the potential effects of these measures. However, if the input and calibration data are not sufficiently detailed there is an inherent risk that the results may be inaccurate. This article presents the use of Floating Car Data to derive useful speed and acceleration values in the process of traffic model calibration as a means of ensuring more accurate results when simulating the effects of particular measures. The data acquired includes instantaneous GPS coordinates to track and select the itineraries, and speed and engine performance extracted directly from the on-board diagnostics system. Once the data is processed, the variations in several calibration parameters can be analyzed by comparing the base case model with the measure application scenarios. Depending on the measure, the results show changes of up to 6.4% in maximum speed values, and reductions of nearly 15% in acceleration and braking levels, especially when eco-driving is applied. Full article

(This article belongs to the Special Issue Positioning and Tracking Sensors and Technologies in Road Transport)

▼ Show Figures

10 pages, 2200 KiB

Open AccessArticle

Synthesis of a Cu²⁺-Selective Probe Derived from Rhodamine and Its Application in Cell Imaging

by Chunwei Yu^†, Yingying Wen^† and Jun Zhang^*

¹ Laboratory of Environmental Monitoring, School of Tropical and Laboratory Medicine, Hainan Medical University, Haikou 571199, China

^† These authors contributed equally to this work.

Sensors 2014, 14(11), 21375-21384; https://doi.org/10.3390/s141121375 - 12 Nov 2014

Cited by 12 | Viewed by 6447

Abstract

A new fluorescent probe P based on rhodamine for Cu²⁺ was synthesized and characterized. The new probe P showed high selectivity to Cu²⁺ over other tested metal ions. With optimal conditions, the proposed probe P worked in a wide linear range [...] Read more.

A new fluorescent probe P based on rhodamine for Cu²⁺ was synthesized and characterized. The new probe P showed high selectivity to Cu²⁺ over other tested metal ions. With optimal conditions, the proposed probe P worked in a wide linear range of 1.0 × 10⁻⁶–1.0 × 10⁻⁵ M with a detection limit of 3.3 × 10⁻⁷ M Cu²⁺ in ethanol-water solution (9:1, v:v, 20 mM HEPES, pH 7.0). Furthermore, it has been used for imaging of Cu²⁺ in living cells with satisfying results. Full article

(This article belongs to the Special Issue Molecular Sensing and Molecular Electronics)

▼ Show Figures

24 pages, 3081 KiB

Open AccessArticle

An Algorithm for Retrieving Land Surface Temperatures Using VIIRS Data in Combination with Multi-Sensors

by Lang Xia¹, Kebiao Mao^1,*, Ying Ma¹, Fen Zhao¹, Lipeng Jiang², Xinyi Shen³ and Zhihao Qin¹

¹ National Hulunber Grassland Ecosystem Observation and Research Station, Institute of Agricultural Resources and Regional Planning, Chinese Academy of Agricultural Sciences, Beijing 100081, China

² National Meteorological Information Center, China Meteorological Administration, Beijing 100081, China

³ Hydrometeorology and Remote Sensing Laboratory, University of Oklahoma, Norman, OK 73072, USA

Sensors 2014, 14(11), 21385-21408; https://doi.org/10.3390/s141121385 - 12 Nov 2014

Cited by 12 | Viewed by 5416

Abstract

A practical algorithm was proposed to retrieve land surface temperature (LST) from Visible Infrared Imager Radiometer Suite (VIIRS) data in mid-latitude regions. The key parameter transmittance is generally computed from water vapor content, while water vapor channel is absent in VIIRS data. In [...] Read more.

A practical algorithm was proposed to retrieve land surface temperature (LST) from Visible Infrared Imager Radiometer Suite (VIIRS) data in mid-latitude regions. The key parameter transmittance is generally computed from water vapor content, while water vapor channel is absent in VIIRS data. In order to overcome this shortcoming, the water vapor content was obtained from Moderate Resolution Imaging Spectroradiometer (MODIS) data in this study. The analyses on the estimation errors of vapor content and emissivity indicate that when the water vapor errors are within the range of ±0.5 , the mean retrieval error of the present algorithm is 0.634 K; while the land surface emissivity errors range from −0.005 to +0.005, the mean retrieval error is less than 1.0 K. Validation with the standard atmospheric simulation shows the average LST retrieval error for the twenty-three land types is 0.734 K, with a standard deviation value of 0.575 K. The comparison between the ground station LST data indicates the retrieval mean accuracy is −0.395 K, and the standard deviation value is 1.490 K in the regions with vegetation and water cover. Besides, the retrieval results of the test data have also been compared with the results measured by the National Oceanic and Atmospheric Administration (NOAA) VIIRS LST products, and the results indicate that 82.63% of the difference values are within the range of −1 to 1 K, and 17.37% of the difference values are within the range of ±2 to ±1 K. In a conclusion, with the advantages of multi-sensors taken fully exploited, more accurate results can be achieved in the retrieval of land surface temperature. Full article

(This article belongs to the Section Remote Sensors)

▼ Show Figures

9 pages, 868 KiB

Open AccessArticle

Using Bio-Functionalized Magnetic Nanoparticles and Dynamic Nuclear Magnetic Resonance to Characterize the Time-Dependent Spin-Spin Relaxation Time for Sensitive Bio-Detection

by Shu-Hsien Liao^1,*

, Kuen-Lin Chen^2,3, Chun-Ming Wang¹, Jen-Jie Chieh¹, Herng-Er Horng¹, Li-Min Wang^4,*, C. H. Wu³ and Hong-Chang Yang²

¹ Institute of Electro-Optical Science and Technology, National Taiwan Normal University, Taipei 116, Taiwan

² Department of Electro-Optical Engineering, Kun Shan University, Tainan 710, Taiwan

³ Department of Physics, National Chung Hsing University, Taichung 402, Taiwan

⁴ Graduate Institute of Applied Physics and Department of Physics, National Taiwan University, Taipei 106, Taiwan

Sensors 2014, 14(11), 21409-21417; https://doi.org/10.3390/s141121409 - 12 Nov 2014

Cited by 13 | Viewed by 5985

Abstract

In this work, we report the use of bio-functionalized magnetic nanoparticles (BMNs) and dynamic magnetic resonance (DMR) to characterize the time-dependent spin-spin relaxation time for sensitive bio-detection. The biomarkers are the human C-reactive protein (CRP) while the BMNs are the anti-CRP bound onto [...] Read more.

In this work, we report the use of bio-functionalized magnetic nanoparticles (BMNs) and dynamic magnetic resonance (DMR) to characterize the time-dependent spin-spin relaxation time for sensitive bio-detection. The biomarkers are the human C-reactive protein (CRP) while the BMNs are the anti-CRP bound onto dextran-coated Fe₃O₄ particles labeled as Fe₃O₄-antiCRP. It was found the time-dependent spin-spin relaxation time, T₂, of protons decreases as time evolves. Additionally, the ΔT₂ of of protons in BMNs increases as the concentration of CRP increases. We attribute these to the formation of the magnetic clusters that deteriorate the field homogeneity of nearby protons. A sensitivity better than 0.1 μg/mL for assaying CRP is achieved, which is much higher than that required by the clinical criteria (0.5 mg/dL). The present MR-detection platform shows promise for further use in detecting tumors, viruses, and proteins. Full article

(This article belongs to the Special Issue Nanoparticle-Based Biosensors)

▼ Show Figures

13 pages, 879 KiB

Open AccessArticle

Effect of CSA Concentration on the Ammonia Sensing Properties of CSA-Doped PA6/PANI Composite Nanofibers

by Zengyuan Pang, Jiapeng Fu, Pengfei Lv, Fenglin Huang and Qufu Wei^*

Key Laboratory of Eco-Textiles, Ministry of Education, Jiangnan University, Wuxi 214122, Jiangsu, China

Sensors 2014, 14(11), 21453-21465; https://doi.org/10.3390/s141121453 - 13 Nov 2014

Cited by 25 | Viewed by 7099

Abstract

Camphor sulfonic acid (CSA)-doped polyamide 6/polyaniline (PA6/PANI) composite nanofibers were fabricated using in situ polymerization of aniline under different CSA concentrations (0.02, 0.04, 0.06, 0.08 and 0.10 M) with electrospun PA6 nanofibers as templates. The structural, morphological and ammonia sensing properties of the [...] Read more.

Camphor sulfonic acid (CSA)-doped polyamide 6/polyaniline (PA6/PANI) composite nanofibers were fabricated using in situ polymerization of aniline under different CSA concentrations (0.02, 0.04, 0.06, 0.08 and 0.10 M) with electrospun PA6 nanofibers as templates. The structural, morphological and ammonia sensing properties of the prepared composite nanofibers were studied using scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FT-IR), four-point probe techniques, X-ray diffraction (XRD) and a home-made gas sensing test system. All the results indicated that the CSA concentration had a great influence on the sensing properties of CSA-doped PA6/PANI composite nanofibers. The composite nanofibers doped with 0.02 M CSA showed the best ammonia sensing properties, with a significant sensitivity toward ammonia (NH₃) at room temperature, superior to that of the composite nanofibers doped with 0.04–0.10 mol/L CSA. It was found that for high concentrations of CSA, the number of PANI–H⁺ reacted with NH₃ would not make up a high proportion of all PANI–H⁺ within certain limits. As a result, within a certain range even though higher CSA-doped PA6/PANI nanofibers had better conductivity, their ammonia sensing performance would degrade. Full article

(This article belongs to the Section Chemical Sensors)

▼ Show Figures

17 pages, 657 KiB

Open AccessArticle

High Speed Stereovision Setup for Position and Motion Estimation of Fertilizer Particles Leaving a Centrifugal Spreader

by Bilal Hijazi^1,2,3,4, Simon Cool^1,4,*, Jürgen Vangeyte¹, Koen C. Mertens¹

, Frédéric Cointault², Michel Paindavoine³ and Jan G. Pieters⁴

¹ Institute of Agricultural and Fisheries Research, Burg. van Gansberghelaan 115, Merelbeke 9820, Belgium

² Institut National Supérieur des Sciences Agronomiques, de l'Alimentation et de l'Environnement, boulevard du Docteur Petitjean 26, Dijon 21079, France

³ Laboratoire d'Etude de l'Apprentissage et du Developpement, University of Burgundy, Esplanade Erasme 11, Dijon 21000, France

⁴ Department of Biosystems Engineering, Ghent University, Coupure links 653, Gent 9000, Belgium

Sensors 2014, 14(11), 21466-21482; https://doi.org/10.3390/s141121466 - 13 Nov 2014

Cited by 20 | Viewed by 8648

Abstract

A 3D imaging technique using a high speed binocular stereovision system was developed in combination with corresponding image processing algorithms for accurate determination of the parameters of particles leaving the spinning disks of centrifugal fertilizer spreaders. Validation of the stereo-matching algorithm using a [...] Read more.

A 3D imaging technique using a high speed binocular stereovision system was developed in combination with corresponding image processing algorithms for accurate determination of the parameters of particles leaving the spinning disks of centrifugal fertilizer spreaders. Validation of the stereo-matching algorithm using a virtual 3D stereovision simulator indicated an error of less than 2 pixels for 90% of the particles. The setup was validated using the cylindrical spread pattern of an experimental spreader. A 2D correlation coefficient of 90% and a Relative Error of 27% was found between the experimental results and the (simulated) spread pattern obtained with the developed setup. In combination with a ballistic flight model, the developed image acquisition and processing algorithms can enable fast determination and evaluation of the spread pattern which can be used as a tool for spreader design and precise machine calibration. Full article

(This article belongs to the Special Issue Agriculture and Forestry: Sensors, Technologies and Procedures)

▼ Show Figures

14 pages, 1221 KiB

Open AccessArticle

Optimal Fluorescence Waveband Determination for Detecting Defective Cherry Tomatoes Using a Fluorescence Excitation-Emission Matrix

by In-Suck Baek¹

, Moon S. Kim², Hoosoo Lee¹, Wang-Hee Lee¹ and Byoung-Kwan Cho^1,*

¹ Department of Biosystems Machinery Engineering, College of Agricultural and Life Science, Chungnam National University, 99 Daehak-ro, Yuseong-gu, Daejeon 305-764, Korea

² Environmental Microbiology and Food Safety Laboratory, Agricultural Research Service, U.S. Department of Agriculture, Powder Mill Road, Building #303, BARC-East, Beltsville, MD 20705, USA

Sensors 2014, 14(11), 21483-21496; https://doi.org/10.3390/s141121483 - 14 Nov 2014

Cited by 12 | Viewed by 6856

Abstract

A multi-spectral fluorescence imaging technique was used to detect defective cherry tomatoes. The fluorescence excitation and emission matrix was used to measure for defects, sound surface and stem areas to determine the optimal fluorescence excitation and emission wavelengths for discrimination. Two-way ANOVA revealed [...] Read more.

A multi-spectral fluorescence imaging technique was used to detect defective cherry tomatoes. The fluorescence excitation and emission matrix was used to measure for defects, sound surface and stem areas to determine the optimal fluorescence excitation and emission wavelengths for discrimination. Two-way ANOVA revealed the optimal excitation wavelength for detecting defect areas was 410 nm. Principal component analysis (PCA) was applied to the fluorescence emission spectra of all regions at 410 nm excitation to determine the emission wavelengths for defect detection. The major emission wavelengths were 688 nm and 506 nm for the detection. Fluorescence images combined with the determined emission wavebands demonstrated the feasibility of detecting defective cherry tomatoes with >98% accuracy. Multi-spectral fluorescence imaging has potential utility in non-destructive quality sorting of cherry tomatoes. Full article

▼ Show Figures

17 pages, 3219 KiB

Open AccessArticle

Rapid, Time-Division Multiplexed, Direct Absorption- and Wavelength Modulation-Spectroscopy

by Alexander Klein¹, Oliver Witzel¹ and Volker Ebert^1,2,*

¹ Physikalisch-Technische Bundesanstalt, Bundesallee 100, Braunschweig 38116, Germany

² Center of Smart Interfaces, TU Darmstadt, Petersenstraße 32, Darmstadt 64287, Germany

Sensors 2014, 14(11), 21497-21513; https://doi.org/10.3390/s141121497 - 14 Nov 2014

Cited by 79 | Viewed by 9984

Abstract

We present a tunable diode laser spectrometer with a novel, rapid time multiplexed direct absorption- and wavelength modulation-spectroscopy operation mode. The new technique allows enhancing the precision and dynamic range of a tunable diode laser absorption spectrometer without sacrificing accuracy. The spectroscopic technique [...] Read more.

We present a tunable diode laser spectrometer with a novel, rapid time multiplexed direct absorption- and wavelength modulation-spectroscopy operation mode. The new technique allows enhancing the precision and dynamic range of a tunable diode laser absorption spectrometer without sacrificing accuracy. The spectroscopic technique combines the benefits of absolute concentration measurements using calibration-free direct tunable diode laser absorption spectroscopy (dTDLAS) with the enhanced noise rejection of wavelength modulation spectroscopy (WMS). In this work we demonstrate for the first time a 125 Hz time division multiplexed (TDM-dTDLAS-WMS) spectroscopic scheme by alternating the modulation of a DFB-laser between a triangle-ramp (dTDLAS) and an additional 20 kHz sinusoidal modulation (WMS). The absolute concentration measurement via the dTDLAS-technique allows one to simultaneously calibrate the normalized 2f/1f-signal of the WMS-technique. A dTDLAS/WMS-spectrometer at 1.37 µm for H₂O detection was built for experimental validation of the multiplexing scheme over a concentration range from 50 to 3000 ppmV (0.1 MPa, 293 K). A precision of 190 ppbV was achieved with an absorption length of 12.7 cm and an averaging time of two seconds. Our results show a five-fold improvement in precision over the entire concentration range and a significantly decreased averaging time of the spectrometer. Full article

(This article belongs to the Section Physical Sensors)

▼ Show Figures

9 pages, 820 KiB

Open AccessArticle

Surface Roughness Evaluation Based on Acoustic Emission Signals in Robot Assisted Polishing

by Beatriz De Agustina^1,*, Marta María Marín¹, Roberto Teti² and Eva María Rubio¹

¹ Department of Manufacturing Engineering, Industrial Engineering School, National University of Distance Education (UNED), C/Juan del Rosal, 12, E28040-Madrid, Spain

² Department of Materials and Production Engineering, University of Naples Federico II Piazzale Tecchio, 80, Naples 80125, Italy

Sensors 2014, 14(11), 21514-21522; https://doi.org/10.3390/s141121514 - 14 Nov 2014

Cited by 19 | Viewed by 6240

Abstract

The polishing process is the most common technology used in applications where a high level of surface quality is demanded. The automation of polishing processes is especially difficult due to the high level of skill and dexterity that is required. Much of this [...] Read more.

The polishing process is the most common technology used in applications where a high level of surface quality is demanded. The automation of polishing processes is especially difficult due to the high level of skill and dexterity that is required. Much of this difficulty arises because of the lack of reliable data on the effect of the polishing parameters on the resulting surface roughness. An experimental study was developed to evaluate the surface roughness obtained during Robot Assisted Polishing processes by the analysis of acoustic emission signals in the frequency domain. The aim is to find out a trend of a feature or features calculated from the acoustic emission signals detected along the process. Such an evaluation was made with the objective of collecting valuable information for the establishment of the end point detection of polishing process. As a main conclusion, it can be affirmed that acoustic emission (AE) signals can be considered useful to monitor the polishing process state. Full article

(This article belongs to the Section Physical Sensors)

▼ Show Figures

12 pages, 2205 KiB

Open AccessArticle

Electrically Insulated Sensing of Respiratory Rate and Heartbeat Using Optical Fibers

by Ernesto Suaste-Gómez^*, Daniel Hernández-Rivera, Anabel S. Sánchez-Sánchez and Elsy Villarreal-Calva

Electrical Engineering Department, Bioelectronics Section, Centro de Investigación y de Estudios Avanzados del IPN, Av. IPN 2508, Col. San Pedro Zacatenco, C.P. 07360, D.F., Mexico

Sensors 2014, 14(11), 21523-21534; https://doi.org/10.3390/s141121523 - 14 Nov 2014

Cited by 21 | Viewed by 10816

Abstract

Respiratory and heart rates are among the most important physiological parameters used to monitor patients’ health. It is important to design devices that can measure these parameters without risking or altering the subject’s health. In this context, a novel sensing method to monitor [...] Read more.

Respiratory and heart rates are among the most important physiological parameters used to monitor patients’ health. It is important to design devices that can measure these parameters without risking or altering the subject’s health. In this context, a novel sensing method to monitor simultaneously the heartbeat and respiratory rate signals of patients within an electrically safety environment was developed and tested. An optical fiber-based sensor was used in order to detect two optical phenomena. Photo-plethysmography and the relation between bending radius and attenuation of optical fiber were coupled through a single beam light traveling along this fiber. Full article

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

▼ Show Figures

14 pages, 901 KiB

Open AccessArticle

Magnetic Bead-Based Colorimetric Immunoassay for Aflatoxin B1 Using Gold Nanoparticles

by Xu Wang, Reinhard Niessner and Dietmar Knopp^*

Institute of Hydrochemistry and Chemical Balneology, Chair for Analytical Chemistry, Technische Universität München, Marchioninistrasse 17, Munich 81377, Germany

Sensors 2014, 14(11), 21535-21548; https://doi.org/10.3390/s141121535 - 14 Nov 2014

Cited by 73 | Viewed by 12862

Abstract

A competitive colorimetric immunoassay for the detection of aflatoxin B1 (AFB) has been established using biofunctionalized magnetic beads (MBs) and gold nanoparticles (GNPs). Aflatoxin B1-bovine serum albumin conjugates (AFB-BSA) modified MBs were employed as capture probe, which could specifically bind with GNP-labeled anti- [...] Read more.

A competitive colorimetric immunoassay for the detection of aflatoxin B1 (AFB) has been established using biofunctionalized magnetic beads (MBs) and gold nanoparticles (GNPs). Aflatoxin B1-bovine serum albumin conjugates (AFB-BSA) modified MBs were employed as capture probe, which could specifically bind with GNP-labeled anti-AFB antibodies through immunoreaction, while such specific binding was competitively inhibited by the addition of AFB. After magnetic separation, the supernatant solution containing unbound GNPs was directly tested by UV-Vis spectroscopy. The absorption intensity was directly proportional to the AFB concentration. The influence of GNP size, incubation time and pH was investigated in detail. After optimization, the developed method could detect AFB in a linear range from 20 to 800 ng/L, with the limit of detection at 12 ng/L. The recoveries for spiked maize samples ranged from 92.8% to 122.0%. The proposed immunoassay provides a promising approach for simple, rapid, specific and cost-effective detection of toxins in the field of food safety. Full article

(This article belongs to the Special Issue Nanoparticle-Based Biosensors)

▼ Show Figures

16 pages, 880 KiB

Open AccessArticle

Chaotic Extension Neural Network Theory-Based XXY Stage Collision Fault Detection Using a Single Accelerometer Sensor

by Chin-Tsung Hsieh, Her-Terng Yau^*, Shang-Yi Wu and Huo-Cheng Lin

Department of Electrical Engineering, National Chin-Yi University of Technology, Taichung 41170, Taiwan

Sensors 2014, 14(11), 21549-21564; https://doi.org/10.3390/s141121549 - 14 Nov 2014

Cited by 2 | Viewed by 5504

Abstract

The collision fault detection of a XXY stage is proposed for the first time in this paper. The stage characteristic signals are extracted and imported into the master and slave chaos error systems by signal filtering from the vibratory magnitude of the stage. [...] Read more.

The collision fault detection of a XXY stage is proposed for the first time in this paper. The stage characteristic signals are extracted and imported into the master and slave chaos error systems by signal filtering from the vibratory magnitude of the stage. The trajectory diagram is made from the chaos synchronization dynamic error signals E₁ and E₂. The distance between characteristic positive and negative centers of gravity, as well as the maximum and minimum distances of trajectory diagram, are captured as the characteristics of fault recognition by observing the variation in various signal trajectory diagrams. The matter-element model of normal status and collision status is built by an extension neural network. The correlation grade of various fault statuses of the XXY stage was calculated for diagnosis. The dSPACE is used for real-time analysis of stage fault status with an accelerometer sensor. Three stage fault statuses are detected in this study, including normal status, Y collision fault and X collision fault. It is shown that the scheme can have at least 75% diagnosis rate for collision faults of the XXY stage. As a result, the fault diagnosis system can be implemented using just one sensor, and consequently the hardware cost is significantly reduced. Full article

(This article belongs to the Section Sensor Networks)

▼ Show Figures

23 pages, 2910 KiB

Open AccessArticle

An Arch-Shaped Intraoral Tongue Drive System with Built-in Tongue-Computer Interfacing SoC

by Hangue Park and Maysam Ghovanloo^*

GT-Bionics Lab, Georgia Institute of Technology, 85 Fifth St. NW, Atlanta, GA 30308, USA

Sensors 2014, 14(11), 21565-21587; https://doi.org/10.3390/s141121565 - 14 Nov 2014

Cited by 29 | Viewed by 10678

Abstract

We present a new arch-shaped intraoral Tongue Drive System (iTDS) designed to occupy the buccal shelf in the user’s mouth. The new arch-shaped iTDS, which will be referred to as the iTDS-2, incorporates a system-on-a-chip (SoC) that amplifies and digitizes the raw magnetic [...] Read more.

We present a new arch-shaped intraoral Tongue Drive System (iTDS) designed to occupy the buccal shelf in the user’s mouth. The new arch-shaped iTDS, which will be referred to as the iTDS-2, incorporates a system-on-a-chip (SoC) that amplifies and digitizes the raw magnetic sensor data and sends it wirelessly to an external TDS universal interface (TDS-UI) via an inductive coil or a planar inverted-F antenna. A built-in transmitter (Tx) employs a dual-band radio that operates at either 27 MHz or 432 MHz band, according to the wireless link quality. A built-in super-regenerative receiver (SR-Rx) monitors the wireless link quality and switches the band if the link quality is below a predetermined threshold. An accompanying ultra-low power FPGA generates data packets for the Tx and handles digital control functions. The custom-designed TDS-UI receives raw magnetic sensor data from the iTDS-2, recognizes the intended user commands by the sensor signal processing (SSP) algorithm running in a smartphone, and delivers the classified commands to the target devices, such as a personal computer or a powered wheelchair. We evaluated the iTDS-2 prototype using center-out and maze navigation tasks on two human subjects, which proved its functionality. The subjects’ performance with the iTDS-2 was improved by 22% over its predecessor, reported in our earlier publication. Full article

(This article belongs to the Special Issue Miniaturized Wireless Biosensors)

▼ Show Figures

15 pages, 912 KiB

Open AccessArticle

Force Sensor Based Tool Condition Monitoring Using a Heterogeneous Ensemble Learning Model

by Guofeng Wang^*, Yinwei Yang and Zhimeng Li

Key Laboratory of Mechanism Theory and Equipment Design of Ministry of Education, Tianjin University, Tianjin 300072, China

Sensors 2014, 14(11), 21588-21602; https://doi.org/10.3390/s141121588 - 14 Nov 2014

Cited by 41 | Viewed by 7139

Abstract

Tool condition monitoring (TCM) plays an important role in improving machining efficiency and guaranteeing workpiece quality. In order to realize reliable recognition of the tool condition, a robust classifier needs to be constructed to depict the relationship between tool wear states and sensory [...] Read more.

Tool condition monitoring (TCM) plays an important role in improving machining efficiency and guaranteeing workpiece quality. In order to realize reliable recognition of the tool condition, a robust classifier needs to be constructed to depict the relationship between tool wear states and sensory information. However, because of the complexity of the machining process and the uncertainty of the tool wear evolution, it is hard for a single classifier to fit all the collected samples without sacrificing generalization ability. In this paper, heterogeneous ensemble learning is proposed to realize tool condition monitoring in which the support vector machine (SVM), hidden Markov model (HMM) and radius basis function (RBF) are selected as base classifiers and a stacking ensemble strategy is further used to reflect the relationship between the outputs of these base classifiers and tool wear states. Based on the heterogeneous ensemble learning classifier, an online monitoring system is constructed in which the harmonic features are extracted from force signals and a minimal redundancy and maximal relevance (mRMR) algorithm is utilized to select the most prominent features. To verify the effectiveness of the proposed method, a titanium alloy milling experiment was carried out and samples with different tool wear states were collected to build the proposed heterogeneous ensemble learning classifier. Moreover, the homogeneous ensemble learning model and majority voting strategy are also adopted to make a comparison. The analysis and comparison results show that the proposed heterogeneous ensemble learning classifier performs better in both classification accuracy and stability. Full article

(This article belongs to the Section Physical Sensors)

▼ Show Figures

23 pages, 2581 KiB

Open AccessArticle

A 12-Bit High-Speed Column-Parallel Two-Step Single-Slope Analog-to-Digital Converter (ADC) for CMOS Image Sensors

by Tao Lyu, Suying Yao, Kaiming Nie and Jiangtao Xu^*

School of Electronic Information Engineering, Tianjin University, 92 Weijin Road, Nankai District, Tianjin 300072, China

Sensors 2014, 14(11), 21603-21625; https://doi.org/10.3390/s141121603 - 17 Nov 2014

Cited by 19 | Viewed by 12334

Abstract

A 12-bit high-speed column-parallel two-step single-slope (SS) analog-to-digital converter (ADC) for CMOS image sensors is proposed. The proposed ADC employs a single ramp voltage and multiple reference voltages, and the conversion is divided into coarse phase and fine phase to improve the conversion [...] Read more.

A 12-bit high-speed column-parallel two-step single-slope (SS) analog-to-digital converter (ADC) for CMOS image sensors is proposed. The proposed ADC employs a single ramp voltage and multiple reference voltages, and the conversion is divided into coarse phase and fine phase to improve the conversion rate. An error calibration scheme is proposed to correct errors caused by offsets among the reference voltages. The digital-to-analog converter (DAC) used for the ramp generator is based on the split-capacitor array with an attenuation capacitor. Analysis of the DAC’s linearity performance versus capacitor mismatch and parasitic capacitance is presented. A prototype 1024 × 32 Time Delay Integration (TDI) CMOS image sensor with the proposed ADC architecture has been fabricated in a standard 0.18 μm CMOS process. The proposed ADC has average power consumption of 128 μW and a conventional rate 6 times higher than the conventional SS ADC. A high-quality image, captured at the line rate of 15.5 k lines/s, shows that the proposed ADC is suitable for high-speed CMOS image sensors. Full article

(This article belongs to the Section Physical Sensors)

▼ Show Figures

34 pages, 11735 KiB

Open AccessArticle

Multispectral Filter Arrays: Recent Advances and Practical Implementation

by Pierre-Jean Lapray¹, Xingbo Wang^1,2, Jean-Baptiste Thomas^1,* and Pierre Gouton¹

¹ LE2I Laboratory, University of Burgundy, Dijon 21000, France

² Norwegian Colour and Visual Computing Laboratory, Gjøvik University College, Gjøvik 2818, Norway

Sensors 2014, 14(11), 21626-21659; https://doi.org/10.3390/s141121626 - 17 Nov 2014

Cited by 255 | Viewed by 25137

Abstract

Thanks to some technical progress in interferencefilter design based on different technologies, we can finally successfully implement the concept of multispectral filter array-based sensors. This article provides the relevant state-of-the-art for multispectral imaging systems and presents the characteristics of the elements of our [...] Read more.

Thanks to some technical progress in interferencefilter design based on different technologies, we can finally successfully implement the concept of multispectral filter array-based sensors. This article provides the relevant state-of-the-art for multispectral imaging systems and presents the characteristics of the elements of our multispectral sensor as a case study. The spectral characteristics are based on two different spatial arrangements that distribute eight different bandpass filters in the visible and near-infrared area of the spectrum. We demonstrate that the system is viable and evaluate its performance through sensor spectral simulation. Full article

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

▼ Show Figures

16 pages, 1527 KiB

Open AccessArticle

Wireless and Simultaneous Detections of Multiple Bio-Molecules in a Single Sensor Using Love Wave Biosensor

by Haekwan Oh¹, Chen Fu², Kunnyun Kim¹ and Keekeun Lee^2,*

¹ Korea Electronics Technology Institute, Seongnam-si, Gyeonggi-do 463-816, Korea

² Department of Electronics Engineering, Ajou University, Suwon, Gyeonggi-do 443-749, Korea

Sensors 2014, 14(11), 21660-21675; https://doi.org/10.3390/s141121660 - 17 Nov 2014

Cited by 20 | Viewed by 6584

Abstract

A Love wave-based biosensor with a 440 MHz center frequency was developed for the simultaneous detection of two different analytes of Cartilage Oligomeric Matrix Protein (COMP) and rabbit immunoglobulin G (IgG) in a single sensor. The developed biosensor consists of one-port surface acoustic [...] Read more.

A Love wave-based biosensor with a 440 MHz center frequency was developed for the simultaneous detection of two different analytes of Cartilage Oligomeric Matrix Protein (COMP) and rabbit immunoglobulin G (IgG) in a single sensor. The developed biosensor consists of one-port surface acoustic wave (SAW) reflective delay lines on a 41° YX LiNbO₃ piezoelectric substrate, a poly(methyl methacrylate) (PMMA) waveguide layer, and two different sensitive films. The Love wave biosensor was wirelessly characterized using two antennas and a network analyzer. The binding of the analytes to the sensitive layers induced a large change in the time positions of the original reflection peaks mainly due to the mass loading effect. The assessed time shifts in the reflection peaks were matched well with the predicted values from coupling of mode (COM) modeling. The sensitivities evaluated from the sensitive films were ~15 deg/µg/mL for the rabbit IgG and ~1.8 deg/ng/mL for COMP. Full article

(This article belongs to the Special Issue Miniaturized Wireless Biosensors)

▼ Show Figures

17 pages, 757 KiB

Open AccessArticle

Investigation into Alternative Sample Preparation Techniques for the Determination of Heavy Metals in Stationary Source Emission Samples Collected on Quartz Filters

by Sharon L. Goddard^* and Richard J. C. Brown

Analytical Science Division, National Physical Laboratory, Teddington, Middlesex TW11 0LW, UK

Sensors 2014, 14(11), 21676-21692; https://doi.org/10.3390/s141121676 - 17 Nov 2014

Cited by 14 | Viewed by 6931

Abstract

Monitoring stationary source emissions for heavy metals generally requires the use of quartz filters to collect samples because of the high temperature and high moisture sampling environment. The documentary standard method sample preparation technique in Europe, EN 14385, uses digestion in hydrofluoric acid [...] Read more.

Monitoring stationary source emissions for heavy metals generally requires the use of quartz filters to collect samples because of the high temperature and high moisture sampling environment. The documentary standard method sample preparation technique in Europe, EN 14385, uses digestion in hydrofluoric acid and nitric acid (HF/HNO₃) followed by complexing with boric acid (H₃BO₃) prior to analysis. However, the use of this method presents a number of problems, including significant instrumental drift during analysis caused by the matrix components, often leading to instrument breakdown and downtime for repairs, as well as posing significant health and safety risks. The aim of this work was to develop an alternative sample preparation technique for emissions samples on quartz filters. The alternative techniques considered were: (i) acid digestion in a fluoroboric acid (HBF₄) and HNO₃mixture and (ii) acid extraction in an aqua regia (AR) mixture (HCl and HNO₃). Assessment of the effectiveness of these options included determination of interferences and signal drift, as well as validating the different methods by measurement of matrix certified reference materials (CRMs), and comparing the results obtained from real test samples and sample blanks to determine limits of detection. The results showed that the HBF₄/HNO₃ mixture provides the most viable alternative to the documentary standard preparation technique. Full article

(This article belongs to the Special Issue Modern Technologies for Sensing Pollution in Air, Water, and Soil)

▼ Show Figures

9 pages, 347 KiB

Open AccessArticle

Fibre Tip Sensors for Localised Temperature Sensing Based on Rare Earth-Doped Glass Coatings

by Erik P. Schartner^* and Tanya M. Monro

ARC Centre of Excellence for Nanoscale BioPhotonics and Institute for Photonics and Advanced Sensing and School of Chemistry and Physics, The University of Adelaide, Adelaide 5005, Australia

Sensors 2014, 14(11), 21693-21701; https://doi.org/10.3390/s141121693 - 17 Nov 2014

Cited by 40 | Viewed by 7695

Abstract

We report the development of a point temperature sensor, based on monitoring upconversion emission from erbium:ytterbium-doped tellurite coatings on the tips of optical fibres. The dip coating technique allows multiple sensors to be fabricated simultaneously, while confining the temperature-sensitive region to a localised [...] Read more.

We report the development of a point temperature sensor, based on monitoring upconversion emission from erbium:ytterbium-doped tellurite coatings on the tips of optical fibres. The dip coating technique allows multiple sensors to be fabricated simultaneously, while confining the temperature-sensitive region to a localised region on the end-face of the fibre. The strong response of the rare earth ions to changing temperature allows a resolution of 0.1–0.3 °C to be recorded over the biologically relevant range of temperatures from 23–39 °C. Full article

(This article belongs to the Section Physical Sensors)

▼ Show Figures

20 pages, 32259 KiB

Open AccessArticle

Hardware Architecture and Cutting-Edge Assembly Process of a Tiny Curved Compound Eye

by Stéphane Viollet^1,*, Stéphanie Godiot², Robert Leitel³, Wolfgang Buss³, Patrick Breugnon², Mohsine Menouni², Raphaël Juston¹, Fabien Expert¹, Fabien Colonnier¹, Géraud L'Eplattenier⁴, Andreas Brückner³, Felix Kraze³, Hanspeter Mallot⁵, Nicolas Franceschini¹, Ramon Pericet-Camara⁴, Franck Ruffier¹

and Dario Floreano⁴

¹ Aix-Marseille Université, CNRS, UMR 7287 ISM, 13288 Marseille, France

² Aix-Marseille Université, CNRS, UMR 7346 CPPM, 13288 Marseille, France

³ Fraunhofer Institute for Applied Optics and Precision Engineering, 07745 Jena, Germany

⁴ Laboratory of Intelligent Systems, École Polytechnique Fédérale de Lausanne, CH-1015 Lausanne, Switzerland

⁵ Laboratory of Cognitive Neuroscience, Department of Biology, University of Tübingen, 72076 Tübingen, Germany

Sensors 2014, 14(11), 21702-21721; https://doi.org/10.3390/s141121702 - 17 Nov 2014

Cited by 31 | Viewed by 11147

Abstract

The demand for bendable sensors increases constantly in the challenging field of soft and micro-scale robotics. We present here, in more detail, the flexible, functional, insect-inspired curved artificial compound eye (CurvACE) that was previously introduced in the Proceedings of the National Academy of [...] Read more.

The demand for bendable sensors increases constantly in the challenging field of soft and micro-scale robotics. We present here, in more detail, the flexible, functional, insect-inspired curved artificial compound eye (CurvACE) that was previously introduced in the Proceedings of the National Academy of Sciences (PNAS, 2013). This cylindrically-bent sensor with a large panoramic field-of-view of \(180^\circ\) \(\times\) \(60^\circ\)composed of 630 artificial ommatidia weighs only 1.75 g, is extremely compact and power-lean (0.9 W), while it achieves unique visual motion sensing performance (1950 frames per second) in a five-decade range of illuminance. In particular, this paper details the innovative Very Large Scale Integration (VLSI) sensing layout, the accurate assembly fabrication process, the innovative, new fast read-out interface, as well as the auto-adaptive dynamic response of the CurvACE sensor. Starting from photodetectors and microoptics on wafer substrates and flexible printed circuit board, the complete assembly of CurvACE was performed in a planar configuration, ensuring high alignment accuracy and compatibility with state-of-the art assembling processes. The characteristics of the photodetector of one artificial ommatidium have been assessed in terms of their dynamic response to light steps. We also characterized the local auto-adaptability of CurvACE photodetectors in response to large illuminance changes: this feature will certainly be of great interest for future applications in real indoor and outdoor environments. Full article

(This article belongs to the Section Physical Sensors)

▼ Show Figures

24 pages, 4695 KiB

Open AccessArticle

Face Recognition System for Set-Top Box-Based Intelligent TV

by Won Oh Lee, Yeong Gon Kim, Hyung Gil Hong and Kang Ryoung Park^*

Division of Electronics and Electrical Engineering, Dongguk University, 26 Pil-dong 3-ga, Jung-gu, Seoul 100-715, Korea

Sensors 2014, 14(11), 21726-21749; https://doi.org/10.3390/s141121726 - 18 Nov 2014

Cited by 21 | Viewed by 9166

Abstract

Despite the prevalence of smart TVs, many consumers continue to use conventional TVs with supplementary set-top boxes (STBs) because of the high cost of smart TVs. However, because the processing power of a STB is quite low, the smart TV functionalities that can [...] Read more.

Despite the prevalence of smart TVs, many consumers continue to use conventional TVs with supplementary set-top boxes (STBs) because of the high cost of smart TVs. However, because the processing power of a STB is quite low, the smart TV functionalities that can be implemented in a STB are very limited. Because of this, negligible research has been conducted regarding face recognition for conventional TVs with supplementary STBs, even though many such studies have been conducted with smart TVs. In terms of camera sensors, previous face recognition systems have used high-resolution cameras, cameras with high magnification zoom lenses, or camera systems with panning and tilting devices that can be used for face recognition from various positions. However, these cameras and devices cannot be used in intelligent TV environments because of limitations related to size and cost, and only small, low cost web-cameras can be used. The resulting face recognition performance is degraded because of the limited resolution and quality levels of the images. Therefore, we propose a new face recognition system for intelligent TVs in order to overcome the limitations associated with low resource set-top box and low cost web-cameras. We implement the face recognition system using a software algorithm that does not require special devices or cameras. Our research has the following four novelties: first, the candidate regions in a viewer’s face are detected in an image captured by a camera connected to the STB via low processing background subtraction and face color filtering; second, the detected candidate regions of face are transmitted to a server that has high processing power in order to detect face regions accurately; third, in-plane rotations of the face regions are compensated based on similarities between the left and right half sub-regions of the face regions; fourth, various poses of the viewer’s face region are identified using five templates obtained during the initial user registration stage and multi-level local binary pattern matching. Experimental results indicate that the recall; precision; and genuine acceptance rate were about 95.7%; 96.2%; and 90.2%, respectively. Full article

(This article belongs to the Special Issue HCI In Smart Environments)

▼ Show Figures

20 pages, 1792 KiB

Open AccessArticle

Locally-Referenced Ultrasonic – LPS for Localization and Navigation

by David Gualda^*, Jesús Ureña, Juan C. García

and Alejandro Lindo

Electronics Department, University of Alcalá de Henares, Escuela Politécnica. Ctra. Madrid-Barcelona, Km. 33,600, 28871 Alcalá de Henares, Spain

Sensors 2014, 14(11), 21750-21769; https://doi.org/10.3390/s141121750 - 18 Nov 2014

Cited by 23 | Viewed by 6217

Abstract

This paper presents a flexible deployment of ultrasonic position sensors and a novel positioning algorithm suitable for the navigation of mobile robots (MRs) in extensive indoor environments. Our proposal uses several independently-referenced local positioning systems (LPS), which means that each one of them [...] Read more.

This paper presents a flexible deployment of ultrasonic position sensors and a novel positioning algorithm suitable for the navigation of mobile robots (MRs) in extensive indoor environments. Our proposal uses several independently-referenced local positioning systems (LPS), which means that each one of them operates within its own local reference system. In a typical layout, an indoor extensive area can be covered using just a reduced set of globally-referenced LPS (GRLPS), whose beacon positions are known to the global reference system, while the rest of the space can be covered using locally-referenced LPSs (LRLPS) that can be distributed arbitrarily. The number of LRLPS and their position can be also changed at any moment. The algorithm is composed of several Bayesian filters running in parallel, so that when an MR is under the GRLPS coverage area, its position is updated by a global filter, whereas when the MR is inside the LRLPS area, its position is updated using position increments within a local filter. The navigation algorithm has been tested by simulation and with actual data obtained using a real set of ultrasonic LPSs. Full article

(This article belongs to the Special Issue Sensors for Indoor Mapping and Navigation)

▼ Show Figures

21 pages, 5371 KiB

Open AccessArticle

An Improved Flexible Telemetry System to Autonomously Monitor Sub-Bandage Pressure and Wound Moisture

by Nasir Mehmood^1,*, Alex Hariz¹, Sue Templeton² and Nicolas H. Voelcker³

¹ School of Engineering, University of South Australia, Adelaide, SA 5001, Australia

² Royal District Nursing Service, Adelaide, SA 5035, Australia

³ Mawson Institute, University of South Australia, Adelaide, SA 5001, Australia

Sensors 2014, 14(11), 21770-21790; https://doi.org/10.3390/s141121770 - 18 Nov 2014

Cited by 31 | Viewed by 10397

Abstract

This paper presents the development of an improved mobile-based telemetric dual mode sensing system to monitor pressure and moisture levels in compression bandages and dressings used for chronic wound management. The system is fabricated on a 0.2 mm thick flexible printed circuit material, [...] Read more.

This paper presents the development of an improved mobile-based telemetric dual mode sensing system to monitor pressure and moisture levels in compression bandages and dressings used for chronic wound management. The system is fabricated on a 0.2 mm thick flexible printed circuit material, and is capable of sensing pressure and moisture at two locations simultaneously within a compression bandage and wound dressing. The sensors are calibrated to sense both parameters accurately, and the data are then transmitted wirelessly to a receiver connected to a mobile device. An error-correction algorithm is developed to compensate the degradation in measurement quality due to battery power drop over time. An Android application is also implemented to automatically receive, process, and display the sensed wound parameters. The performance of the sensing system is first validated on a mannequin limb using a compression bandage and wound dressings, and then tested on a healthy volunteer to acquire real-time performance parameters. The results obtained here suggest that this dual mode sensor can perform reliably when placed on a human limb. Full article

(This article belongs to the Section Physical Sensors)

▼ Show Figures

35 pages, 6232 KiB

Open AccessArticle

Sampling-Based Real-Time Motion Planning under State Uncertainty for Autonomous Micro-Aerial Vehicles in GPS-Denied Environments

by Dachuan Li^1,*, Qing Li¹, Nong Cheng^1,2 and Jingyan Song¹

¹ Department of Automation, Tsinghua University, Bejing 100084, China

² National Key Laboratory on Flight Vehicle Control Integrated Technology, Flight Automatic Control Research Institute, Xi'an 710065, China

Sensors 2014, 14(11), 21791-21825; https://doi.org/10.3390/s141121791 - 18 Nov 2014

Cited by 9 | Viewed by 7139

Abstract

This paper presents a real-time motion planning approach for autonomous vehicles with complex dynamics and state uncertainty. The approach is motivated by the motion planning problem for autonomous vehicles navigating in GPS-denied dynamic environments, which involves non-linear and/or non-holonomic vehicle dynamics, incomplete state [...] Read more.

This paper presents a real-time motion planning approach for autonomous vehicles with complex dynamics and state uncertainty. The approach is motivated by the motion planning problem for autonomous vehicles navigating in GPS-denied dynamic environments, which involves non-linear and/or non-holonomic vehicle dynamics, incomplete state estimates, and constraints imposed by uncertain and cluttered environments. To address the above motion planning problem, we propose an extension of the closed-loop rapid belief trees, the closed-loop random belief trees (CL-RBT), which incorporates predictions of the position estimation uncertainty, using a factored form of the covariance provided by the Kalman filter-based estimator. The proposed motion planner operates by incrementally constructing a tree of dynamically feasible trajectories using the closed-loop prediction, while selecting candidate paths with low uncertainty using efficient covariance update and propagation. The algorithm can operate in real-time, continuously providing the controller with feasible paths for execution, enabling the vehicle to account for dynamic and uncertain environments. Simulation results demonstrate that the proposed approach can generate feasible trajectories that reduce the state estimation uncertainty, while handling complex vehicle dynamics and environment constraints. Full article

(This article belongs to the Special Issue Positioning and Tracking Sensors and Technologies in Road Transport)

▼ Show Figures

17 pages, 9595 KiB

Open AccessArticle

Design of a WSN for the Sampling of Environmental Variability in Complex Terrain

by Miguel A. Martín-Tardío^* and Ángel M. Felicísimo

Centro Universitario de Mérida, Universidad de Extremadura, Mérida 06800, Spain

Sensors 2014, 14(11), 21826-21842; https://doi.org/10.3390/s141121826 - 18 Nov 2014

Cited by 3 | Viewed by 5814

Abstract

In-situ environmental parameter measurements using sensor systems connected to a wireless network have become widespread, but the problem of monitoring large and mountainous areas by means of a wireless sensor network (WSN) is not well resolved. The main reasons for this are: (1) [...] Read more.

In-situ environmental parameter measurements using sensor systems connected to a wireless network have become widespread, but the problem of monitoring large and mountainous areas by means of a wireless sensor network (WSN) is not well resolved. The main reasons for this are: (1) the environmental variability distribution is unknown in the field; (2) without this knowledge, a huge number of sensors would be necessary to ensure the complete coverage of the environmental variability and (3) WSN design requirements, for example, effective connectivity (intervisibility), limiting distances and controlled redundancy, are usually solved by trial and error. Using temperature as the target environmental variable, we propose: (1) a method to determine the homogeneous environmental classes to be sampled using the digital elevation model (DEM) and geometric simulations and (2) a procedure to determine an effective WSN design in complex terrain in terms of the number of sensors, redundancy, cost and spatial distribution. The proposed methodology, based on geographic information systems and binary integer programming can be easily adapted to a wide range of applications that need exhaustive and continuous environmental monitoring with high spatial resolution. The results show that the WSN design is perfectly suited to the topography and the technical specifications of the sensors, and provides a complete coverage of the environmental variability in terms of Sun exposure. However these results still need be validated in the field and the proposed procedure must be refined. Full article

(This article belongs to the Section Remote Sensors)

▼ Show Figures

15 pages, 843 KiB

Open AccessArticle

Rapid Immunoenzyme Assay of Aflatoxin B1 Using Magnetic Nanoparticles

by Alexandr E. Urusov^1,†, Alina V. Petrakova^1,†, Maxim V. Vozniak², Anatoly V. Zherdev¹

and Boris B. Dzantiev^1,*

¹ Bach Institute of Biochemistry of the Russian Academy of Sciences, Leninsky Prospect 33, Moscow 119071, Russia

² IL Test-Pushchino Ltd., Gruzovaya Street 1g, Pushchino 142290, Moscow Region, Russia

^† These authors contributed equally to this work.

Sensors 2014, 14(11), 21843-21857; https://doi.org/10.3390/s141121843 - 18 Nov 2014

Cited by 61 | Viewed by 9646

Abstract

The main limitations of microplate-based enzyme immunoassays are the prolonged incubations necessary to facilitate heterogeneous interactions, the complex matrix and poorly soluble antigens, and the significant sample dilutions often required because of the presence of organic extractants. This study presents the use of [...] Read more.

The main limitations of microplate-based enzyme immunoassays are the prolonged incubations necessary to facilitate heterogeneous interactions, the complex matrix and poorly soluble antigens, and the significant sample dilutions often required because of the presence of organic extractants. This study presents the use of antibody immobilization on the surface of magnetic particles to overcome these limitations in the detection of the mycotoxin, aflatoxin B1. Features of the proposed system are a high degree of nanoparticle dispersion and methodologically simple immobilization of the antibodies by adsorption. Reactions between the immobilized antibodies with native and labeled antigens are conducted in solution, thereby reducing the interaction period to 5 min without impairing the analytical outcome. Adsorption of immunoglobulins on the surface of magnetic nanoparticles increases their stability in aqueous-organic media, thus minimizing the degree of sample dilution required. Testing barley and maize extracts demonstrated a limit of aflatoxin B1 detection equal to 20 pg/mL and total assay duration of 20 min. Using this method, only the 3-fold dilution of the initial methanol/water (60/40) extraction mixture in the microplate wells is necessary. The proposed pseudo-homogeneous approach could be applied toward immunodetection of a wide range of compounds. Full article

(This article belongs to the Special Issue Nanoparticle-Based Biosensors)

▼ Show Figures

14 pages, 1455 KiB

Open AccessArticle

A Sub-Clustering Algorithm Based on Spatial Data Correlation for Energy Conservation in Wireless Sensor Networks

by Ming-Hui Tsai and Yueh-Min Huang^*

Department of Engineering Science, National Cheng-Kung University, No.1, University Road, Tainan City 701, Taiwan

Sensors 2014, 14(11), 21858-21871; https://doi.org/10.3390/s141121858 - 18 Nov 2014

Cited by 10 | Viewed by 5523

Abstract

Wireless sensor networks (WSNs) have emerged as a promising solution for various applications due to their low cost and easy deployment. Typically, their limited power capability, i.e., battery powered, make WSNs encounter the challenge of extension of network lifetime. Many hierarchical protocols [...] Read more.

Wireless sensor networks (WSNs) have emerged as a promising solution for various applications due to their low cost and easy deployment. Typically, their limited power capability, i.e., battery powered, make WSNs encounter the challenge of extension of network lifetime. Many hierarchical protocols show better ability of energy efficiency in the literature. Besides, data reduction based on the correlation of sensed readings can efficiently reduce the amount of required transmissions. Therefore, we use a sub-clustering procedure based on spatial data correlation to further separate the hierarchical (clustered) architecture of a WSN. The proposed algorithm (2TC-cor) is composed of two procedures: the prediction model construction procedure and the sub-clustering procedure. The energy conservation benefits by the reduced transmissions, which are dependent on the prediction model. Also, the energy can be further conserved because of the representative mechanism of sub-clustering. As presented by simulation results, it shows that 2TC-cor can effectively conserve energy and monitor accurately the environment within an acceptable level. Full article

(This article belongs to the Section Sensor Networks)

▼ Show Figures

17 pages, 2757 KiB

Open AccessArticle

Rapid Detection of Chloramphenicol Residues in Aquatic Products Using Colloidal Gold Immunochromatographic Assay

by Chennan Zhou¹, Xueyin Zhang¹, Xinxin Huang², Xishan Guo^1,*, Qiang Cai³ and Songming Zhu¹

¹ College of Biosystems Engineering and Food Science, Zhejiang University, Hangzhou 310058, China

² Shanghai Entry-Exit Inspection and Quarantine Bureau, Shanghai 200000, China

³ Yangtze Delta Region Institute of Tsinghua University, Jiaxing 310013, China

Sensors 2014, 14(11), 21872-21888; https://doi.org/10.3390/s141121872 - 18 Nov 2014

Cited by 39 | Viewed by 10692

Abstract

A colloidal gold immunochromatographic assay (GICA) was developed for rapid detection of chloramphenicol (CAP) residues in aquatic products. A nitrocellulose (NC) membrane was used as the carrier, and the polyclonal CAP antibody was used as the marker protein. The average diameter of as-prepared [...] Read more.

A colloidal gold immunochromatographic assay (GICA) was developed for rapid detection of chloramphenicol (CAP) residues in aquatic products. A nitrocellulose (NC) membrane was used as the carrier, and the polyclonal CAP antibody was used as the marker protein. The average diameter of as-prepared colloidal gold nanoparticles (AuNPs) was about 20 nm. The optimal pH value of colloidal gold solutions and the amount of the antibody of CAP were 8.0 and 7.2 μg/mL, respectively. The CAP antibody was immobilized onto the conjugate pad after purification. The CAP conjugate and goat anti-rabbit IgG (secondary antibody) were coated onto the NC membrane. Next, the non-specific sites were blocked with 1% bovine serum albumin. The minimum detectable concentration of CAP in standard solution is 0.5 ng/mL, with good reproducibility. For the real samples from crucian carps injected with a single-dose of CAP in the dorsal muscles, the minimum detectable concentration of CAP residues was 0.5 µg/kg. The chromatographic analysis time was less than 10 min, and the strip had a long storage lifetime of more than 90 days at different temperatures. The strips provide a means for rapid detection of CAP residues in aquatic products. Full article

(This article belongs to the Special Issue Immunosensors 2014)

▼ Show Figures

16 pages, 2155 KiB

Open AccessArticle

The Benefit of 3D Laser Scanning Technology in the Generation and Calibration of FEM Models for Health Assessment of Concrete Structures

by Hao Yang^*,†, Xiangyang Xu^*,† and Ingo Neumann^*,†

¹ Geodetic Institute, Faculty of Civil Engineering and Geodetic Science, Leibniz University Hanover, Nienburger Street 1. D-30167, Hanover, Germany

^† These authors contributed equally to this work.

Sensors 2014, 14(11), 21889-21904; https://doi.org/10.3390/s141121889 - 19 Nov 2014

Cited by 55 | Viewed by 9010

Abstract

Terrestrial laser scanning technology (TLS) is a new technique for quickly getting three-dimensional information. In this paper we research the health assessment of concrete structures with a Finite Element Method (FEM) model based on TLS. The goal focuses on the benefits of 3D [...] Read more.

Terrestrial laser scanning technology (TLS) is a new technique for quickly getting three-dimensional information. In this paper we research the health assessment of concrete structures with a Finite Element Method (FEM) model based on TLS. The goal focuses on the benefits of 3D TLS in the generation and calibration of FEM models, in order to build a convenient, efficient and intelligent model which can be widely used for the detection and assessment of bridges, buildings, subways and other objects. After comparing the finite element simulation with surface-based measurement data from TLS, the FEM model is determined to be acceptable with an error of less than 5%. The benefit of TLS lies mainly in the possibility of a surface-based validation of results predicted by the FEM model. Full article

(This article belongs to the Section Physical Sensors)

▼ Show Figures

18 pages, 3377 KiB

Open AccessArticle

Cobalt Phthalocyanine Modified Electrodes Utilised in Electroanalysis: Nano-Structured Modified Electrodes vs. Bulk Modified Screen-Printed Electrodes

by Christopher W. Foster¹, Jeseelan Pillay², Jonathan P. Metters¹ and Craig E. Banks^1,*

¹ Faculty of Science and Engineering, School of Chemistry and the Environment, Division of Chemistry and Environmental Science, Manchester Metropolitan University, Chester Street, Manchester M15 GD, Lancs, UK

² Nanotechnology Innovation Centre, Advanced Materials Division, Mintek, 200 Malibongwe Drive, Randburg 2125, South Africa

Sensors 2014, 14(11), 21905-21922; https://doi.org/10.3390/s141121905 - 19 Nov 2014

Cited by 70 | Viewed by 9507

Abstract

Cobalt phthalocyanine (CoPC) compounds have been reported to provide electrocatalytic performances towards a substantial number of analytes. In these configurations, electrodes are typically constructed via drop casting the CoPC onto a supporting electrode substrate, while in other cases the CoPC complex is incorporated [...] Read more.

Cobalt phthalocyanine (CoPC) compounds have been reported to provide electrocatalytic performances towards a substantial number of analytes. In these configurations, electrodes are typically constructed via drop casting the CoPC onto a supporting electrode substrate, while in other cases the CoPC complex is incorporated within the ink of a screen-printed sensor, providing a one-shot economical and disposable electrode configuration. In this paper we critically compare CoPC modified electrodes prepared by drop casting CoPC nanoparticles (nano-CoPC) onto a range of carbon based electrode substrates with that of CoPC bulk modified screen-printed electrodes in the sensing of the model analytes L-ascorbic acid, oxygen and hydrazine. It is found that no “electrocatalysis” is observed towards L-ascorbic acid using either of these CoPC modified electrode configurations and that the bare underlying carbon electrode is the origin of the obtained voltammetric signal, which gives rise to useful electroanalytical signatures, providing new insights into literature reports where “electrocatalysis” has been reported with no clear control experiments undertaken. On the other hand true electrocatalysis is observed towards hydrazine, where no such voltammetric features are witnessed on the bare underlying electrode substrate. Full article

(This article belongs to the Special Issue Printed Sensors)

▼ Show Figures

18 pages, 1110 KiB

Open AccessArticle

Dual Resonant Frequencies Effects on an Induction-Based Oil Palm Fruit Sensor

by Noor Hasmiza Harun^1,3, Norhisam Misron^1,2,*, Roslina Mohd Sidek¹, Ishak Aris¹, Hiroyuki Wakiwaka⁴ and Kunihisa Tashiro⁴

¹ Faculty of Engineering, University Putra Malaysia, Serdang 43400, Selangor, Malaysia

² Institute of Advanced Technology (ITMA), University Putra Malaysia, Serdang 43400, Selangor, Malaysia

³ University Kuala Lumpur-British Malaysian Institute, Batu 8, Jalan Sg Pusu, Gombak 53100, Selangor, Malaysia

⁴ Faculty of Engineering, Shinshu University, Wakasato 4-17-1, Nagano 380-8553, Japan

Sensors 2014, 14(11), 21923-21940; https://doi.org/10.3390/s141121923 - 19 Nov 2014

Cited by 9 | Viewed by 6214

Abstract

As the main exporter in the oil palm industry, the need to improve the quality of palm oil has become the main interest among all the palm oil millers in Malaysia. To produce good quality palm oil, it is important for the miller [...] Read more.

As the main exporter in the oil palm industry, the need to improve the quality of palm oil has become the main interest among all the palm oil millers in Malaysia. To produce good quality palm oil, it is important for the miller to harvest a good oil palm Fresh Fruit Bunch (FFB). Conventionally, the main reference used by Malaysian harvesters is the manual grading standard published by the Malaysian Palm Oil Board (MPOB). A good oil palm FFB consists of all matured fruitlets, aged between 18 to 21 weeks of antheses (WAA). To expedite the harvesting process, it is crucial to implement an automated detection system for determining the maturity of the oil palm FFB. Various automated detection methods have been proposed by researchers in the field to replace the conventional method. In our preliminary study, a novel oil palm fruit sensor to detect the maturity of oil palm fruit bunch was proposed. The design of the proposed air coil sensor based on the inductive sensor was further investigated mainly in the context of the effect of coil diameter to improve its sensitivity. In this paper, the sensitivity of the inductive sensor was further examined with a dual flat-type shape of air coil. The dual air coils were tested on fifteen samples of fruitlet from two categories, namely ripe and unripe. Samples were tested within 20 Hz to 10 MHz while evaluations on both peaks were done separately before the gap between peaks was analyzed. A comparative analysis was conducted to investigate the improvement in sensitivity of the induction-based oil palm fruit sensor as compared to previous works. Results from the comparative study proved that the inductive sensor using a dual flat-type shape air coil has improved by up to 167%. This provides an indication in the improvement in the coil sensitivity of the palm oil fruit sensor based on the induction concept. Full article

(This article belongs to the Section Physical Sensors)

▼ Show Figures

9 pages, 4910 KiB

Open AccessArticle

The Coefficient of the Voltage Induced Frequency Shift Measurement on a Quartz Tuning Fork

by Yubin Hou¹ and Qingyou Lu^1,2,*

¹ High Magnetic Field Laboratory, Chinese Academy of Sciences, Hefei 230031, China

² Hefei National Laboratory for Physical Sciences at Microscale, University of Science and Technology of China, Hefei 230026, China

Sensors 2014, 14(11), 21941-21949; https://doi.org/10.3390/s141121941 - 19 Nov 2014

Cited by 1 | Viewed by 7231

Abstract

We have measured the coefficient of the voltage induced frequency shift (VIFS) of a 32.768 KHz quartz tuning fork. Three vibration modes were studied: one prong oscillating, two prongs oscillating in the same direction, and two prongs oscillating in opposite directions. They all [...] Read more.

We have measured the coefficient of the voltage induced frequency shift (VIFS) of a 32.768 KHz quartz tuning fork. Three vibration modes were studied: one prong oscillating, two prongs oscillating in the same direction, and two prongs oscillating in opposite directions. They all showed a parabolic dependence of the eigen-frequency shift on the bias voltage applied across the fork, due to the voltage-induced internal stress, which varies as the fork oscillates. The average coefficient of the VIFS effect is as low as several hundred nano-Hz per millivolt, implying that fast-response voltage-controlled oscillators and phase-locked loops with nano-Hz resolution can be built. Full article

(This article belongs to the Section Physical Sensors)

▼ Show Figures

18 pages, 15339 KiB

Open AccessArticle

A Combined Method for Segmentation and Registration for an Advanced and Progressive Evaluation of Thermal Images

by Emilio Z. Barcelos^1,2,3,*, Walmir M. Caminhas², Eraldo Ribeiro³, Eduardo M. Pimenta⁴ and Reinaldo M. Palhares²

¹ Department of Electrical Engineering, Federal University of Triangulo Mineiro, Av. Dr. Randolfo Borges Jr. 1250, Univerdecidade, CEP 38064.200, Uberaba, MG, Brazil

² Department of Electronics Engineering, Graduate Program in Electrical Engineering, Federal University of Minas Gerais, Av. Antonio Carlos 6627, Pampulha, CEP 31270.901, Belo Horizonte, MG, Brazil

³ Department of Computer Sciences, Florida Institute of Technology, 150 West University Blvd, Melbourne, FL 32901, USA

⁴ Medical and Physiology Department, Cruzeiro Esporte Clube, R. Adolfo Lippi Fonseca, 251, Céu Azul, CEP 31545.260, Belo Horizonte, MG, Brazil

Sensors 2014, 14(11), 21950-21967; https://doi.org/10.3390/s141121950 - 19 Nov 2014

Cited by 21 | Viewed by 8703

Abstract

In this paper, a method that combines image analysis techniques, such as segmentation and registration, is proposed for an advanced and progressive evaluation of thermograms. The method is applied for the prevention of muscle injury in high-performance athletes, in collaboration with a Brazilian [...] Read more.

In this paper, a method that combines image analysis techniques, such as segmentation and registration, is proposed for an advanced and progressive evaluation of thermograms. The method is applied for the prevention of muscle injury in high-performance athletes, in collaboration with a Brazilian professional soccer club. The goal is to produce information on spatio-temporal variations of thermograms favoring the investigation of the athletes’ conditions along the competition. The proposed method improves on current practice by providing a means for automatically detecting adaptive body-shaped regions of interest, instead of the manual selection of simple shapes. Specifically, our approach combines the optimization features in Otsu’s method with a correction factor and post-processing techniques, enhancing thermal-image segmentation when compared to other methods. Additional contributions resulting from the combination of the segmentation and registration steps of our approach are the progressive analyses of thermograms in a unique spatial coordinate system and the accurate extraction of measurements and isotherms. Full article

(This article belongs to the Section Physical Sensors)

▼ Show Figures

13 pages, 2154 KiB

Open AccessArticle

Raman Imaging with a Fiber-Coupled Multichannel Spectrograph

by Elmar Schmälzlin^1,*, Benito Moralejo¹, Monika Rutowska¹, Ana Monreal-Ibero^1,2, Christer Sandin¹, Nicolae Tarcea³, Jürgen Popp^3,4 and Martin M. Roth^1,5

¹ Leibniz-Institut für Astrophysik Potsdam (AIP), An der Sternwarte 16, Potsdam 14482, Germany

² GEPI Observatoire de Paris, CNRS, Université Paris Diderot, Place Jules Janssen, Meudon 92190, France

³ Institute of Physical Chemistry, Helmholtzweg 4, Jena 07743, Germany

⁴ Leibniz Institute of Photonic Technology, Albert-Einstein-Straße 9, Jena 07745, Germany

⁵ Institut für Physik und Astronomie, Universität Potsdam, Karl-Liebknecht-Str. 24-25, Potsdam 14476, Germany

Sensors 2014, 14(11), 21968-21980; https://doi.org/10.3390/s141121968 - 20 Nov 2014

Cited by 58 | Viewed by 10576

Abstract

Until now, spatially resolved Raman Spectroscopy has required to scan a sample under investigation in a time-consuming step-by-step procedure. Here, we present a technique that allows the capture of an entire Raman image with only one single exposure. The Raman scattering arising from [...] Read more.

Until now, spatially resolved Raman Spectroscopy has required to scan a sample under investigation in a time-consuming step-by-step procedure. Here, we present a technique that allows the capture of an entire Raman image with only one single exposure. The Raman scattering arising from the sample was collected with a fiber-coupled high-performance astronomy spectrograph. The probe head consisting of an array of 20 × 20 multimode fibers was linked to the camera port of a microscope. To demonstrate the high potential of this new concept, Raman images of reference samples were recorded. Entire chemical maps were received without the need for a scanning procedure. Full article

(This article belongs to the Section Physical Sensors)

▼ Show Figures

20 pages, 6067 KiB

Open AccessArticle

Off-Grid Direction of Arrival Estimation Based on Joint Spatial Sparsity for Distributed Sparse Linear Arrays

by Yujie Liang^*, Rendong Ying, Zhenqi Lu and Peilin Liu

School of Electronic Information and Electrical Engineering, Shanghai Jiaotong University, 800 Dongchuan Road, Shanghai 200240, China

Sensors 2014, 14(11), 21981-22000; https://doi.org/10.3390/s141121981 - 20 Nov 2014

Cited by 9 | Viewed by 6677

Abstract

In the design phase of sensor arrays during array signal processing, the estimation performance and system cost are largely determined by array aperture size. In this article, we address the problem of joint direction-of-arrival (DOA) estimation with distributed sparse linear arrays (SLAs) and [...] Read more.

In the design phase of sensor arrays during array signal processing, the estimation performance and system cost are largely determined by array aperture size. In this article, we address the problem of joint direction-of-arrival (DOA) estimation with distributed sparse linear arrays (SLAs) and propose an off-grid synchronous approach based on distributed compressed sensing to obtain larger array aperture. We focus on the complex source distribution in the practical applications and classify the sources into common and innovation parts according to whether a signal of source can impinge on all the SLAs or a specific one. For each SLA, we construct a corresponding virtual uniform linear array (ULA) to create the relationship of random linear map between the signals respectively observed by these two arrays. The signal ensembles including the common/innovation sources for different SLAs are abstracted as a joint spatial sparsity model. And we use the minimization of concatenated atomic norm via semidefinite programming to solve the problem of joint DOA estimation. Joint calculation of the signals observed by all the SLAs exploits their redundancy caused by the common sources and decreases the requirement of array size. The numerical results illustrate the advantages of the proposed approach. Full article

(This article belongs to the Section Physical Sensors)

▼ Show Figures

20 pages, 411 KiB

Open AccessArticle

Behavior Life Style Analysis for Mobile Sensory Data in Cloud Computing through MapReduce

by Shujaat Hussain¹, Jae Hun Bang¹

, Manhyung Han¹, Muhammad Idris Ahmed¹, Muhammad Bilal Amin¹, Sungyoung Lee^1,*, Chris Nugent²

, Sally McClean³, Bryan Scotney³ and Gerard Parr³

¹ Department of Computer Engineering, Kyung Hee University, Suwon 446-701, Korea

² School of Computing and Information Engineering, University of Ulster, Newtownabbey, Co. Antrim, BT38 0QB, UK

³ School of Computing and Information Engineering, University of Ulster, Coleraine, Co. Londonderry, BT52 1SA, UK

Sensors 2014, 14(11), 22001-22020; https://doi.org/10.3390/s141122001 - 20 Nov 2014

Cited by 23 | Viewed by 8542

Abstract

Cloud computing has revolutionized healthcare in today’s world as it can be seamlessly integrated into a mobile application and sensor devices. The sensory data is then transferred from these devices to the public and private clouds. In this paper, a hybrid and distributed [...] Read more.

Cloud computing has revolutionized healthcare in today’s world as it can be seamlessly integrated into a mobile application and sensor devices. The sensory data is then transferred from these devices to the public and private clouds. In this paper, a hybrid and distributed environment is built which is capable of collecting data from the mobile phone application and store it in the cloud. We developed an activity recognition application and transfer the data to the cloud for further processing. Big data technology Hadoop MapReduce is employed to analyze the data and create user timeline of user’s activities. These activities are visualized to find useful health analytics and trends. In this paper a big data solution is proposed to analyze the sensory data and give insights into user behavior and lifestyle trends. Full article

(This article belongs to the Special Issue Sensors Data Fusion for Healthcare)

▼ Show Figures

18 pages, 1428 KiB

Open AccessArticle

Design of a Novel Flexible Capacitive Sensing Mattress for Monitoring Sleeping Respiratory

by Wen-Ying Chang¹, Chien-Chun Huang^2,*, Chi-Chun Chen¹, Chih-Cheng Chang³ and Chin-Lung Yang^1,*

¹ Department of Electrical Engineering, National Cheng-Kung University, Tainan 701, Taiwan

² Biomedical Electronics Translational Research Center, National Chiao Tung University, Hsinchu 300, Taiwan

³ Division of Pulmonary Medicine, Department of Internal Medicine, Shuang Ho Hospital, Taipei Medical University, Taipei 235, Taiwan

Sensors 2014, 14(11), 22021-22038; https://doi.org/10.3390/s141122021 - 20 Nov 2014

Cited by 20 | Viewed by 8911

Abstract

In this paper, an algorithm to extract respiration signals using a flexible projected capacitive sensing mattress (FPCSM) designed for personal health assessment is proposed. Unlike the interfaces of conventional measurement systems for poly-somnography (PSG) and other alternative contemporary systems, the proposed FPCSM uses [...] Read more.

In this paper, an algorithm to extract respiration signals using a flexible projected capacitive sensing mattress (FPCSM) designed for personal health assessment is proposed. Unlike the interfaces of conventional measurement systems for poly-somnography (PSG) and other alternative contemporary systems, the proposed FPCSM uses projected capacitive sensing capability that is not worn or attached to the body. The FPCSM is composed of a multi-electrode sensor array that can not only observe gestures and motion behaviors, but also enables the FPCSM to function as a respiration monitor during sleep using the proposed approach. To improve long-term monitoring when body movement is possible, the FPCSM enables the selection of data from the sensing array, and the FPCSM methodology selects the electrodes with the optimal signals after the application of a channel reduction algorithm that counts the reversals in the capacitive sensing signals as a quality indicator. The simple algorithm is implemented in the time domain. The FPCSM system is used in experimental tests and is simultaneously compared with a commercial PSG system for verification. Multiple synchronous measurements are performed from different locations of body contact, and parallel data sets are collected. The experimental comparison yields a correlation coefficient of 0.88 between FPCSM and PSG, demonstrating the feasibility of the system design. Full article

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

▼ Show Figures

26 pages, 2531 KiB

Open AccessArticle

IoT-Based User-Driven Service Modeling Environment for a Smart Space Management System

by Hoan-Suk Choi

and Woo-Seop Rhee^*

Department of Multimedia Engineering, Hanbat National University, Daejeon 305-719, Korea

Sensors 2014, 14(11), 22039-22064; https://doi.org/10.3390/s141122039 - 20 Nov 2014

Cited by 18 | Viewed by 10107

Abstract

The existing Internet environment has been extended to the Internet of Things (IoT) as an emerging new paradigm. The IoT connects various physical entities. These entities have communication capability and deploy the observed information to various service areas such as building management, energy-saving [...] Read more.

The existing Internet environment has been extended to the Internet of Things (IoT) as an emerging new paradigm. The IoT connects various physical entities. These entities have communication capability and deploy the observed information to various service areas such as building management, energy-saving systems, surveillance services, and smart homes. These services are designed and developed by professional service providers. Moreover, users’ needs have become more complicated and personalized with the spread of user-participation services such as social media and blogging. Therefore, some active users want to create their own services to satisfy their needs, but the existing IoT service-creation environment is difficult for the non-technical user because it requires a programming capability to create a service. To solve this problem, we propose the IoT-based user-driven service modeling environment to provide an easy way to create IoT services. Also, the proposed environment deploys the defined service to another user. Through the personalization and customization of the defined service, the value and dissemination of the service is increased. This environment also provides the ontology-based context-information processing that produces and describes the context information for the IoT-based user-driven service. Full article

(This article belongs to the Special Issue Wireless Sensor Networks and the Internet of Things)

▼ Show Figures

17 pages, 1880 KiB

Open AccessArticle

Development of a Personal Integrated Environmental Monitoring System

by Man Sing Wong^*,†

, Tsan Pong Yip^† and Esmond Mok^†

¹ Department of Land Surveying and Geo-Informatics, The Hong Kong Polytechnic University, Hong Kong

^† These authors contributed equally to this work.

Sensors 2014, 14(11), 22065-22081; https://doi.org/10.3390/s141122065 - 20 Nov 2014

Cited by 20 | Viewed by 10671

Abstract

Environmental pollution in the urban areas of Hong Kong has become a serious public issue but most urban inhabitants have no means of judging their own living environment in terms of dangerous threshold and overall livability. Currently there exist many low-cost sensors such [...] Read more.

Environmental pollution in the urban areas of Hong Kong has become a serious public issue but most urban inhabitants have no means of judging their own living environment in terms of dangerous threshold and overall livability. Currently there exist many low-cost sensors such as ultra-violet, temperature and air quality sensors that provide reasonably accurate data quality. In this paper, the development and evaluation of Integrated Environmental Monitoring System (IEMS) are illustrated. This system consists of three components: (i) position determination and sensor data collection for real-time geospatial-based environmental monitoring; (ii) on-site data communication and visualization with the aid of an Android-based application; and (iii) data analysis on a web server. This system has shown to be working well during field tests in a bus journey and a construction site. It provides an effective service platform for collecting environmental data in near real-time, and raises the public awareness of environmental quality in micro-environments. Full article

(This article belongs to the Section Remote Sensors)

▼ Show Figures

17 pages, 1353 KiB

Open AccessArticle

Overcoming the Challenges of BeiDou Receiver Implementation

by Mohammad Zahidul H. Bhuiyan^*, Stefan Söderholm, Sarang Thombre, Laura Ruotsalainen and Heidi Kuusniemi

Department of Navigation and Positioning, Finnish Geodetic Institute, 02430 Kirkkonummi, Finland

Sensors 2014, 14(11), 22082-22098; https://doi.org/10.3390/s141122082 - 21 Nov 2014

Cited by 31 | Viewed by 8522

Abstract

Global Navigation Satellite System (GNSS)-based positioning is experiencing rapid changes. The existing GPS and the GLONASS systems are being modernized to better serve the current challenging applications under harsh signal conditions. These modernizations include increasing the number of transmission frequencies and changes to [...] Read more.

Global Navigation Satellite System (GNSS)-based positioning is experiencing rapid changes. The existing GPS and the GLONASS systems are being modernized to better serve the current challenging applications under harsh signal conditions. These modernizations include increasing the number of transmission frequencies and changes to the signal components. In addition, the Chinese BeiDou Navigation Satellite system (BDS) and the European Galileo are currently under development for global operation. Therefore, in view of these new upcoming systems the research and development of GNSS receivers has been experiencing a new upsurge. In this article, the authors discuss the main functionalities of a GNSS receiver in view of BDS. While describing the main functionalities of a software-defined BeiDou receiver, the authors also highlight the similarities and differences between the signal characteristics of the BeiDou B1 open service signal and the legacy GPS L1 C/A signal, as in general they both exhibit similar characteristics. In addition, the authors implement a novel acquisition technique for long coherent integration in the presence of NH code modulation in BeiDou D1 signal. Furthermore, a simple phase-preserved coherent integration based acquisition scheme is implemented for BeiDou GEO satellite acquisition. Apart from the above BeiDou-specific implementations, a novel Carrier-to-Noise-density ratio estimation technique is also implemented in the software receiver, which does not necessarily require bit synchronization prior to estimation. Finally, the authors present a BeiDou-only position fix with the implemented software-defined BeiDou receiver considering all three satellite constellations from BDS. In addition, a true multi-GNSS position fix with GPS and BDS systems is also presented while comparing their performances for a static stand-alone code phase-based positioning. Full article

(This article belongs to the Section Remote Sensors)

▼ Show Figures

14 pages, 990 KiB

Open AccessArticle

Development of a Piezoelectric Vacuum Sensing Component for a Wide Pressure Range

by Bing-Yu Wang¹, Fan-Chun Hsieh², Che-Yu Lin¹, Shao-En Chen¹, Fong-Zhi Chen² and Chia-Che Wu^1,*

¹ Department of Mechanical Engineering, National Chung Hsing University, 250, Taichung 402, Taiwan

² Instrument Technology Research Center, National Applied Research Laboratories, 20, R&D Rd. VI, Hsinchu Science Park, Hsinchu 300, Taiwan

Sensors 2014, 14(11), 22099-22112; https://doi.org/10.3390/s141122099 - 21 Nov 2014

Cited by 4 | Viewed by 7559

Abstract

In this study, we develop a clamped–clamped beam-type piezoelectric vacuum pressure sensing element. The clamped–clamped piezoelectric beam is composed of a PZT layer and a copper substrate. A pair of electrodes is set near each end. An input voltage is applied to a [...] Read more.

In this study, we develop a clamped–clamped beam-type piezoelectric vacuum pressure sensing element. The clamped–clamped piezoelectric beam is composed of a PZT layer and a copper substrate. A pair of electrodes is set near each end. An input voltage is applied to a pair of electrodes to vibrate the piezoelectric beam, and the output voltage is measured at the other pair. Because the viscous forces on the piezoelectric beam vary at different air pressures, the vibration of the beam depends on the vacuum pressure. The developed pressure sensor can sense a wide range of pressure, from 6.5 × 10⁻⁶ to 760 Torr. The experimental results showed that the output voltage is inversely proportional to the gas damping ratio, and thus, the vacuum pressure was estimated from the output voltage. Full article

(This article belongs to the Special Issue Sensors for Fluid Leak Detection)

▼ Show Figures

15 pages, 663 KiB

Open AccessArticle

A System for Traffic Violation Detection

by Nourdine Aliane^*, Javier Fernandez^†, Mario Mata^† and Sergio Bemposta^†

¹ Universidad Europea de Madrid, C/Tajo S/N, Urb el Bosque, Villaviciosa de Odón, Madrid 28670, Spain

^† These authors contributed equally to this work.

Sensors 2014, 14(11), 22113-22127; https://doi.org/10.3390/s141122113 - 24 Nov 2014

Cited by 21 | Viewed by 13309

Abstract

This paper describes the framework and components of an experimental platform for an advanced driver assistance system (ADAS) aimed at providing drivers with a feedback about traffic violations they have committed during their driving. The system is able to detect some specific traffic [...] Read more.

This paper describes the framework and components of an experimental platform for an advanced driver assistance system (ADAS) aimed at providing drivers with a feedback about traffic violations they have committed during their driving. The system is able to detect some specific traffic violations, record data associated to these faults in a local data-base, and also allow visualization of the spatial and temporal information of these traffic violations in a geographical map using the standard Google Earth tool. The test-bed is mainly composed of two parts: a computer vision subsystem for traffic sign detection and recognition which operates during both day and nighttime, and an event data recorder (EDR) for recording data related to some specific traffic violations. The paper covers firstly the description of the hardware architecture and then presents the policies used for handling traffic violations. Full article

(This article belongs to the Special Issue Positioning and Tracking Sensors and Technologies in Road Transport)

▼ Show Figures

12 pages, 1624 KiB

Open AccessArticle

Novel Membrane-Based Electrochemical Sensor for Real-Time Bio-Applications

by Fatima AlZahra'a Alatraktchi^*, Tanya Bakmand, Maria Dimaki and Winnie E. Svendsen

Department of Micro- and Nanotechnology, Technical University of Denmark, Ørsteds Plads, 2800 Kgs. Lyngby, Denmark

Sensors 2014, 14(11), 22128-22139; https://doi.org/10.3390/s141122128 - 24 Nov 2014

Cited by 24 | Viewed by 7538

Abstract

This article presents a novel membrane-based sensor for real-time electrochemical investigations of cellular- or tissue cultures. The membrane sensor enables recording of electrical signals from a cell culture without any signal dilution, thus avoiding loss of sensitivity. Moreover, the porosity of the membrane [...] Read more.

This article presents a novel membrane-based sensor for real-time electrochemical investigations of cellular- or tissue cultures. The membrane sensor enables recording of electrical signals from a cell culture without any signal dilution, thus avoiding loss of sensitivity. Moreover, the porosity of the membrane provides optimal culturing conditions similar to existing culturing techniques allowing more efficient nutrient uptake and molecule release. The patterned sensor electrodes were fabricated on a porous membrane by electron-beam evaporation. The electrochemical performance of the membrane electrodes was characterized by cyclic voltammetry and chronoamperometry, and the detection of synthetic dopamine was demonstrated down to a concentration of 3.1 pM. Furthermore, to present the membrane-sensor functionality the dopamine release from cultured PC12 cells was successfully measured. The PC12 cells culturing experiments showed that the membrane-sensor was suitable as a cell culturing substrate for bio-applications. Real-time measurements of dopamine exocytosis in cell cultures were performed, where the transmitter release was recorded at the point of release. The developed membrane-sensor provides a new functionality to the standard culturing methods, enabling sensitive continuous in vitro monitoring and closely mimicking the in vivo conditions. Full article

(This article belongs to the Section Biosensors)

▼ Show Figures

19 pages, 1259 KiB

Open AccessArticle

Accurate Monitoring and Fault Detection in Wind Measuring Devices through Wireless Sensor Networks

by Komal Saifullah Khan^*,† and Muhammad Tariq^†

¹ Department of Electrical Engineering, National University of Computer & Emerging Sciences (NUCES), Peshawar Campus, Peshawar 25000, Pakistan

^† These authors contributed equally to this work.

Sensors 2014, 14(11), 22140-22158; https://doi.org/10.3390/s141122140 - 24 Nov 2014

Cited by 6 | Viewed by 7029

Abstract

Many wind energy projects report poor performance as low as 60% of the predicted performance. The reason for this is poor resource assessment and the use of new untested technologies and systems in remote locations. Predictions about the potential of an area for [...] Read more.

Many wind energy projects report poor performance as low as 60% of the predicted performance. The reason for this is poor resource assessment and the use of new untested technologies and systems in remote locations. Predictions about the potential of an area for wind energy projects (through simulated models) may vary from the actual potential of the area. Hence, introducing accurate site assessment techniques will lead to accurate predictions of energy production from a particular area. We solve this problem by installing a Wireless Sensor Network (WSN) to periodically analyze the data from anemometers installed in that area. After comparative analysis of the acquired data, the anemometers transmit their readings through a WSN to the sink node for analysis. The sink node uses an iterative algorithm which sequentially detects any faulty anemometer and passes the details of the fault to the central system or main station. We apply the proposed technique in simulation as well as in practical implementation and study its accuracy by comparing the simulation results with experimental results to analyze the variation in the results obtained from both simulation model and implemented model. Simulation results show that the algorithm indicates faulty anemometers with high accuracy and low false alarm rate when as many as 25% of the anemometers become faulty. Experimental analysis shows that anemometers incorporating this solution are better assessed and performance level of implemented projects is increased above 86% of the simulated models. Full article

(This article belongs to the Special Issue Wireless Sensor Networks and the Internet of Things)

▼ Show Figures

Review

Jump to: Editorial, Research

29 pages, 960 KiB

Open AccessReview

Electronic Noses for Environmental Monitoring Applications

by Laura Capelli^*

, Selena Sironi and Renato Del Rosso

Politecnico di Milano, Department of Chemistry, Materials and Chemical Engineering "Giulio Natta", Piazza Leonardo da Vinci 32, Milano 20133, Italy

Sensors 2014, 14(11), 19979-20007; https://doi.org/10.3390/s141119979 - 24 Oct 2014

Cited by 232 | Viewed by 13084

Abstract

Electronic nose applications in environmental monitoring are nowadays of great interest, because of the instruments’ proven capability of recognizing and discriminating between a variety of different gases and odors using just a small number of sensors. Such applications in the environmental field include [...] Read more.

Electronic nose applications in environmental monitoring are nowadays of great interest, because of the instruments’ proven capability of recognizing and discriminating between a variety of different gases and odors using just a small number of sensors. Such applications in the environmental field include analysis of parameters relating to environmental quality, process control, and verification of efficiency of odor control systems. This article reviews the findings of recent scientific studies in this field, with particular focus on the abovementioned applications. In general, these studies prove that electronic noses are mostly suitable for the different applications reported, especially if the instruments are specifically developed and fine-tuned. As a general rule, literature studies also discuss the critical aspects connected with the different possible uses, as well as research regarding the development of effective solutions. However, currently the main limit to the diffusion of electronic noses as environmental monitoring tools is their complexity and the lack of specific regulation for their standardization, as their use entails a large number of degrees of freedom, regarding for instance the training and the data processing procedures. Full article

(This article belongs to the Special Issue State-of-the-Art Sensors Technology in Italy 2014)

▼ Show Figures

34 pages, 1188 KiB

Open AccessReview

A Review of Imaging Techniques for Plant Phenotyping

by Lei Li^1,2,3, Qin Zhang² and Danfeng Huang^3,*

¹ School of Mechanical Engineering, Shanghai Jiaotong University, Shanghai 200240, China

² Center for Precision & Automated Agricultural Systems, Washington State University, 24106 N. Bunn Rd., Prosser, WA 99350, USA

³ School of Agriculture and Biology, Shanghai Jiaotong University, Shanghai 200240, China

Sensors 2014, 14(11), 20078-20111; https://doi.org/10.3390/s141120078 - 24 Oct 2014

Cited by 888 | Viewed by 43587

Abstract

Given the rapid development of plant genomic technologies, a lack of access to plant phenotyping capabilities limits our ability to dissect the genetics of quantitative traits. Effective, high-throughput phenotyping platforms have recently been developed to solve this problem. In high-throughput phenotyping platforms, a [...] Read more.

Given the rapid development of plant genomic technologies, a lack of access to plant phenotyping capabilities limits our ability to dissect the genetics of quantitative traits. Effective, high-throughput phenotyping platforms have recently been developed to solve this problem. In high-throughput phenotyping platforms, a variety of imaging methodologies are being used to collect data for quantitative studies of complex traits related to the growth, yield and adaptation to biotic or abiotic stress (disease, insects, drought and salinity). These imaging techniques include visible imaging (machine vision), imaging spectroscopy (multispectral and hyperspectral remote sensing), thermal infrared imaging, fluorescence imaging, 3D imaging and tomographic imaging (MRT, PET and CT). This paper presents a brief review on these imaging techniques and their applications in plant phenotyping. The features used to apply these imaging techniques to plant phenotyping are described and discussed in this review. Full article

(This article belongs to the Collection Sensors in Agriculture and Forestry)

▼ Show Figures

18 pages, 583 KiB

Open AccessReview

CMOS Time-Resolved, Contact, and Multispectral Fluorescence Imaging for DNA Molecular Diagnostics

by Nan Guo, Ka Wai Cheung, Hiu Tung Wong and Derek Ho^*

Department of Physics and Materials Science, City University of Hong Kong, 83 Tat Chee Avenue, Kowloon, Hong Kong

Sensors 2014, 14(11), 20602-20619; https://doi.org/10.3390/s141120602 - 31 Oct 2014

Cited by 14 | Viewed by 8685

Abstract

Instrumental limitations such as bulkiness and high cost prevent the fluorescence technique from becoming ubiquitous for point-of-care deoxyribonucleic acid (DNA) detection and other in-field molecular diagnostics applications. The complimentary metal-oxide-semiconductor (CMOS) technology, as benefited from process scaling, provides several advanced capabilities such as [...] Read more.

Instrumental limitations such as bulkiness and high cost prevent the fluorescence technique from becoming ubiquitous for point-of-care deoxyribonucleic acid (DNA) detection and other in-field molecular diagnostics applications. The complimentary metal-oxide-semiconductor (CMOS) technology, as benefited from process scaling, provides several advanced capabilities such as high integration density, high-resolution signal processing, and low power consumption, enabling sensitive, integrated, and low-cost fluorescence analytical platforms. In this paper, CMOS time-resolved, contact, and multispectral imaging are reviewed. Recently reported CMOS fluorescence analysis microsystem prototypes are surveyed to highlight the present state of the art. Full article

(This article belongs to the Special Issue Molecular Sensing and Molecular Electronics)

▼ Show Figures

25 pages, 852 KiB

Open AccessReview

Chronically Implanted Pressure Sensors: Challenges and State of the Field

by Lawrence Yu¹, Brian J. Kim¹ and Ellis Meng^1,2,*

¹ Department of Biomedical Engineering, University of Southern California, 1042 Downey Way, DRB-140, Los Angeles, CA 90089-1111, USA

² Ming Hsieh Department of Electrical Engineering, University of Southern California, 3740 McClintock Ave, EEB-100, Los Angeles, CA 90089-2560, USA

Sensors 2014, 14(11), 20620-20644; https://doi.org/10.3390/s141120620 - 31 Oct 2014

Cited by 171 | Viewed by 17178

Abstract

Several conditions and diseases are linked to the elevation or depression of internal pressures from a healthy, normal range, motivating the need for chronic implantable pressure sensors. A simple implantable pressure transduction system consists of a pressure-sensing element with a method to transmit [...] Read more.

Several conditions and diseases are linked to the elevation or depression of internal pressures from a healthy, normal range, motivating the need for chronic implantable pressure sensors. A simple implantable pressure transduction system consists of a pressure-sensing element with a method to transmit the data to an external unit. The biological environment presents a host of engineering issues that must be considered for long term monitoring. Therefore, the design of such systems must carefully consider interactions between the implanted system and the body, including biocompatibility, surgical placement, and patient comfort. Here we review research developments on implantable sensors for chronic pressure monitoring within the body, focusing on general design requirements for implantable pressure sensors as well as specifications for different medical applications. We also discuss recent efforts to address biocompatibility, efficient telemetry, and drift management, and explore emerging trends. Full article

(This article belongs to the Special Issue Implantable Sensors)

▼ Show Figures

18 pages, 2437 KiB

Open AccessReview

Dual-Frequency Piezoelectric Transducers for Contrast Enhanced Ultrasound Imaging

by K. Heath Martin¹, Brooks D. Lindsey¹, Jianguo Ma², Mike Lee³, Sibo Li², F. Stuart Foster³, Xiaoning Jiang² and Paul A. Dayton^1,*

¹ Joint Department of Biomedical Engineering, University of North Carolina at Chapel Hill and North Carolina State University at Raleigh, Chapel Hill, NC 27599, USA

² Department of Mechanical & Aero-Space Engineering, North Carolina State University, Raleigh, NC 27695, USA

³ Sunnybrook Health Sciences Centre, Toronto, ON M4N 3M5, Canada

Sensors 2014, 14(11), 20825-20842; https://doi.org/10.3390/s141120825 - 4 Nov 2014

Cited by 79 | Viewed by 14600

Abstract

For many years, ultrasound has provided clinicians with an affordable and effective imaging tool for applications ranging from cardiology to obstetrics. Development of microbubble contrast agents over the past several decades has enabled ultrasound to distinguish between blood flow and surrounding tissue. Current [...] Read more.

For many years, ultrasound has provided clinicians with an affordable and effective imaging tool for applications ranging from cardiology to obstetrics. Development of microbubble contrast agents over the past several decades has enabled ultrasound to distinguish between blood flow and surrounding tissue. Current clinical practices using microbubble contrast agents rely heavily on user training to evaluate degree of localized perfusion. Advances in separating the signals produced from contrast agents versus surrounding tissue backscatter provide unique opportunities for specialized sensors designed to image microbubbles with higher signal to noise and resolution than previously possible. In this review article, we describe the background principles and recent developments of ultrasound transducer technology for receiving signals produced by contrast agents while rejecting signals arising from soft tissue. This approach relies on transmitting at a low-frequency and receiving microbubble harmonic signals at frequencies many times higher than the transmitted frequency. Design and fabrication of dual-frequency transducers and the extension of recent developments in transducer technology for dual-frequency harmonic imaging are discussed. Full article

(This article belongs to the Special Issue Ultrasonic Sensors and Transducers for Applications in Biology, Medicine and NDT)

▼ Show Figures

52 pages, 3467 KiB

Open AccessReview

Heat Flux Sensors for Infrared Thermography in Convective Heat Transfer

by Giovanni Maria Carlomagno^*,†

, Luigi De Luca^†

, Gennaro Cardone^† and Tommaso Astarita^†

¹ Department of Industrial Engineering, University of Naples Federico II, Piazzale Tecchio 80, Napoli 80125, Italy

^† These authors equally contributed to the present work.

Sensors 2014, 14(11), 21065-21116; https://doi.org/10.3390/s141121065 - 7 Nov 2014

Cited by 23 | Viewed by 11008

Abstract

This paper reviews the most dependable heat flux sensors, which can be used with InfraRed (IR) thermography to measure convective heat transfer coefficient distributions, and some of their applications performed by the authors’ research group at the University of Naples Federico II. After [...] Read more.

This paper reviews the most dependable heat flux sensors, which can be used with InfraRed (IR) thermography to measure convective heat transfer coefficient distributions, and some of their applications performed by the authors’ research group at the University of Naples Federico II. After recalling the basic principles that make IR thermography work, the various heat flux sensors to be used with it are presented and discussed, describing their capability to investigate complex thermo-fluid-dynamic flows. Several applications to streams, which range from natural convection to hypersonic flows, are also described. Full article

(This article belongs to the Special Issue State-of-the-Art Sensors Technology in Italy 2014)

▼ Show Figures

23 pages, 862 KiB

Open AccessReview

Remote Sensing of Ecosystem Health: Opportunities, Challenges, and Future Perspectives

by Zhaoqin Li, Dandan Xu

and Xulin Guo^*

Department of Geography and Planning, University of Saskatchewan, 117 Science Place, Saskatoon, SK S7N 5C8, Canada

Sensors 2014, 14(11), 21117-21139; https://doi.org/10.3390/s141121117 - 7 Nov 2014

Cited by 74 | Viewed by 10917

Abstract

Maintaining a healthy ecosystem is essential for maximizing sustainable ecological services of the best quality to human beings. Ecological and conservation research has provided a strong scientific background on identifying ecological health indicators and correspondingly making effective conservation plans. At the same time, [...] Read more.

Maintaining a healthy ecosystem is essential for maximizing sustainable ecological services of the best quality to human beings. Ecological and conservation research has provided a strong scientific background on identifying ecological health indicators and correspondingly making effective conservation plans. At the same time, ecologists have asserted a strong need for spatially explicit and temporally effective ecosystem health assessments based on remote sensing data. Currently, remote sensing of ecosystem health is only based on one ecosystem attribute: vigor, organization, or resilience. However, an effective ecosystem health assessment should be a comprehensive and dynamic measurement of the three attributes. This paper reviews opportunities of remote sensing, including optical, radar, and LiDAR, for directly estimating indicators of the three ecosystem attributes, discusses the main challenges to develop a remote sensing-based spatially-explicit comprehensive ecosystem health system, and provides some future perspectives. The main challenges to develop a remote sensing-based spatially-explicit comprehensive ecosystem health system are: (1) scale issue; (2) transportability issue; (3) data availability; and (4) uncertainties in health indicators estimated from remote sensing data. However, the Radarsat-2 constellation, upcoming new optical sensors on Worldview-3 and Sentinel-2 satellites, and improved technologies for the acquisition and processing of hyperspectral, multi-angle optical, radar, and LiDAR data and multi-sensoral data fusion may partly address the current challenges. Full article

(This article belongs to the Section Remote Sensors)

▼ Show Figures

35 pages, 4220 KiB

Open AccessReview

The Cup Anemometer, a Fundamental Meteorological Instrument for the Wind Energy Industry. Research at the IDR/UPM Institute

by Santiago Pindado^1,2,*

, Javier Cubas^1,2

and Félix Sorribes-Palmer¹

¹ Instituto Universitario de Microgravedad "Ignacio Da Riva" (IDR/UPM), Universidad Politécnica de Madrid, ETSI Aeronáutica y del Espacio, Pza. Del Cardenal Cisneros 3, Madrid 28040, Spain

² Departamento de Infraestructura, Sistemas Aeroespaciales y Aeropuertos, Universidad Politécnica de Madrid, ETSI Aeronáutica y del Espacio, Pza. Del Cardenal Cisneros 3, Madrid 28040, Spain

Sensors 2014, 14(11), 21418-21452; https://doi.org/10.3390/s141121418 - 12 Nov 2014

Cited by 49 | Viewed by 14029

Abstract

The results of several research campaigns investigating cup anemometer performance carried out since 2008 at the IDR/UPM Institute are included in the present paper. Several analysis of large series of calibrations were done by studying the effect of the rotor’s geometry, climatic conditions [...] Read more.

The results of several research campaigns investigating cup anemometer performance carried out since 2008 at the IDR/UPM Institute are included in the present paper. Several analysis of large series of calibrations were done by studying the effect of the rotor’s geometry, climatic conditions during calibration, and anemometers’ ageing. More specific testing campaigns were done regarding the cup anemometer rotor aerodynamics, and the anemometer signals. The effect of the rotor’s geometry on the cup anemometer transfer function has been investigated experimentally and analytically. The analysis of the anemometer’s output signal as a way of monitoring the anemometer status is revealed as a promising procedure for detecting anomalies. Full article

(This article belongs to the Special Issue Selected Papers from the 1st International Electronic Conference on Sensors and Applications)

▼ Show Figures

Journal Menu

Journal Browser

Sensors, Volume 14, Issue 11 (November 2014) – 119 articles , Pages 19926-22158

Editorial

Research

Review

Further Information

Guidelines

MDPI Initiatives

Follow MDPI