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Sensors, Volume 12, Issue 6 (June 2012) , Pages 6764-8437

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Open AccessCorrection Correction: Renaudin, V. et al. Use of Earth’s Magnetic Field for Mitigating Gyroscope Errors Regardless of Magnetic Perturbation. Sensors 2011, 11, 11390-11414
Sensors 2012, 12(6), 8437; https://doi.org/10.3390/s120608437
Received: 1 June 2012 / Accepted: 20 June 2012 / Published: 20 June 2012
Viewed by 2690 | PDF Full-text (214 KB) | HTML Full-text | XML Full-text
Abstract
Although the equations’ derivation in our paper published in Sensors 2011 [1] is correct, a typo has been found in the summarizing Equations (48) and (49). The dot on the B in the skew matrix should be removed. [...] Full article
(This article belongs to the Section Physical Sensors)
Open AccessArticle Multiplex Immunoassay Platforms Based on Shape-Coded Poly(ethylene glycol) Hydrogel Microparticles Incorporating Acrylic Acid
Sensors 2012, 12(6), 8426-8436; https://doi.org/10.3390/s120608426
Received: 3 May 2012 / Revised: 25 May 2012 / Accepted: 5 June 2012 / Published: 20 June 2012
Cited by 18 | Viewed by 4461 | PDF Full-text (621 KB) | HTML Full-text | XML Full-text
Abstract
A suspension protein microarray was developed using shape-coded poly(ethylene glycol) (PEG) hydrogel microparticles for potential applications in multiplex and high-throughput immunoassays. A simple photopatterning process produced various shapes of hydrogel micropatterns that were weakly bound to poly(dimethylsiloxane) (PDMS)-coated substrates. These micropatterns were easily [...] Read more.
A suspension protein microarray was developed using shape-coded poly(ethylene glycol) (PEG) hydrogel microparticles for potential applications in multiplex and high-throughput immunoassays. A simple photopatterning process produced various shapes of hydrogel micropatterns that were weakly bound to poly(dimethylsiloxane) (PDMS)-coated substrates. These micropatterns were easily detached from substrates during the washing process and were collected as non-spherical microparticles. Acrylic acids were incorporated into hydrogels, which could covalently immobilize proteins onto their surfaces due to the presence of carboxyl groups. The amount of immobilized protein increased with the amount of acrylic acid due to more available carboxyl groups. Saturation was reached at 25% v/v of acrylic acid. Immunoassays with IgG and IgM immobilized onto hydrogel microparticles were successfully performed with a linear concentration range from 0 to 500 ng/mL of anti-IgG and anti-IgM, respectively. Finally, a mixture of two different shapes of hydrogel microparticles immobilizing IgG (circle) and IgM (square) was prepared and it was demonstrated that simultaneous detection of two different target proteins was possible without cross-talk using same fluorescence indicator because each immunoassay was easily identified by the shapes of hydrogel microparticles. Full article
(This article belongs to the Special Issue Micro and Nano Technologies for Point-of-Care Diagnosis)
Open AccessArticle Evaluation of Complexation Ability Using a Sensor Electrode Chip Equipped with a Wireless Screening System
Sensors 2012, 12(6), 8405-8425; https://doi.org/10.3390/s120608405
Received: 12 April 2012 / Revised: 30 May 2012 / Accepted: 11 June 2012 / Published: 19 June 2012
Cited by 2 | Viewed by 2799 | PDF Full-text (591 KB) | HTML Full-text | XML Full-text
Abstract
We fabricated an electrode chip with a structure coated by an insulation layer that contains dispersed SiO2 adsorbent particles modified by an amino-group on a source-drain electrode. Voltage changes caused by chelate molecule adsorption onto electrode surfaces and by specific cation interactions [...] Read more.
We fabricated an electrode chip with a structure coated by an insulation layer that contains dispersed SiO2 adsorbent particles modified by an amino-group on a source-drain electrode. Voltage changes caused by chelate molecule adsorption onto electrode surfaces and by specific cation interactions were investigated. The detection of specific cations without the presence of chelate molecules on the free electrode was also examined. By comparing both sets of results the complexation ability of the studied chelate molecules onto the electrode was evaluated. Five pairs of source-drain electrodes (×8 arrays) were fabricated on a glass substrate of 20 × 30 mm in size. The individual Au/Cr (1.0/0.1 μm thickness) electrodes had widths of 50 μm and an inter-electrode interval of 100 μm. The fabricated source-drain electrodes were further coated with an insulation layer comprising a porous SiO2 particle modified amino-group to adsorb the chelate molecules. The electrode chip was equipped with a handy-type sensor signal analyzer that was mounted on an amplifier circuit using a MinishipTM or a system in a packaged LSI device. For electrode surfaces containing different adsorbed chelate molecules an increase in the sensor voltage depended on a combination of host-guest reactions and generally decreased in the following order: 5,10,15,20-tetrakis(N-methylpyridinium-4-yl)-21H,23H-porphine, tetrakis(p-toluenesulfonate) (TMPyP) as a Cu2+ chelator and Cu2+ > 2-nitroso-5-[N-n-propyl-N-(3-sulfopropyl)amino]phenol (nitroso-PSAP) as an Fe2+ chelator and Fe2+ > 4,7-diphenyl-1,10-phenanthrolinedisulfonic acid, disodium salt (BPDSA) as an Fe2+ chelator and Fe2+ > 3-[3-(2,4-dimethylphenylcarbamoyl)-2-hydroxynaphthalene-1-yl-azo]-4-hydroxybenzenesulfonic acid, sodium salt (XB-1) as a Mg2+ chelator and Mg2+ > 2,9-dimethyl-4,7-diphenyl-1,10-phenanthrolinedisulfonic acid, disodium salt (BCIDSA) as a Cu2+ chelator and Cu2+, respectively. In contrast, for the electrode surfaces with adsorbed O,O'-bis(2-aminoethyl)ethyleneglycol-N,N,N',N'-tetraacetic acid (GEDTA) or O,O'-bis(2-aminophenyl)ethyleneglycol-N,N,N',N'-tetraacetic acid, tetrapotassium salt, hydrate (BAPTA) as a Ca2+ chelator no increase in the detection voltage was found for all the electrode tests conducted in the presence of Ca2+. To determine the differences in electrode detection, molecular orbital (MO) calculations of the chelate molecules and surface molecular modeling of the adsorbents were carried out. In accordance with frontier orbital theory, the lowest unoccupied MO (LUMO) of the chelate molecules can accept two lone pair electrons at the highest occupied MO (HOMO) of the amino group on the model surface structure of the SiO2 particle. As a result, a good correlation was obtained between the LUMO-HOMO difference and the ion response of all the electrodes tested. Based on the results obtained, the order of adsorbed chelate molecules on adsorption particles reflects the different metal ion detection abilities of the electrode chips. Full article
(This article belongs to the Special Issue Selective Chelating Agents)
Open AccessArticle Direct Measurement of Mammographic X-Ray Spectra with a Digital CdTe Detection System
Sensors 2012, 12(6), 8390-8404; https://doi.org/10.3390/s120608390
Received: 8 May 2012 / Revised: 11 June 2012 / Accepted: 12 June 2012 / Published: 18 June 2012
Cited by 19 | Viewed by 3465 | PDF Full-text (487 KB) | HTML Full-text | XML Full-text
Abstract
In this work we present a detection system, based on a CdTe detector and an innovative digital pulse processing (DPP) system, for high-rate X-ray spectroscopy in mammography (1–30 keV). The DPP system performs a height and shape analysis of the detector pulses, sampled [...] Read more.
In this work we present a detection system, based on a CdTe detector and an innovative digital pulse processing (DPP) system, for high-rate X-ray spectroscopy in mammography (1–30 keV). The DPP system performs a height and shape analysis of the detector pulses, sampled and digitized by a 14-bit, 100 MHz ADC. We show the results of the characterization of the detection system both at low and high photon counting rates by using monoenergetic X-ray sources and a nonclinical X-ray tube. The detection system exhibits excellent performance up to 830 kcps with an energy resolution of 4.5% FWHM at 22.1 keV. Direct measurements of clinical molybdenum X-ray spectra were carried out by using a pinhole collimator and a custom alignment device. A comparison with the attenuation curves and the half value layer values, obtained from the measured and simulated spectra, from an ionization chamber and from a solid state dosimeter, also shows the accuracy of the measurements. These results make the proposed detection system a very attractive tool for both laboratory research, calibration of dosimeters and advanced quality controls in mammography. Full article
(This article belongs to the Special Issue Ultra-Small Sensor Systems and Components)
Open AccessReview Fiber Optic-Based Refractive Index Sensing at INESC Porto
Sensors 2012, 12(6), 8371-8389; https://doi.org/10.3390/s120608371
Received: 2 May 2012 / Revised: 4 June 2012 / Accepted: 6 June 2012 / Published: 18 June 2012
Cited by 19 | Viewed by 3859 | PDF Full-text (430 KB) | HTML Full-text | XML Full-text
Abstract
A review of refractive index measurement based on different types of optical fiber sensor configurations and techniques is presented. It addresses the main developments in the area, with particular focus on results obtained at INESC Porto, Portugal. The optical fiber sensing structures studied [...] Read more.
A review of refractive index measurement based on different types of optical fiber sensor configurations and techniques is presented. It addresses the main developments in the area, with particular focus on results obtained at INESC Porto, Portugal. The optical fiber sensing structures studied include those based on Bragg and long period gratings, on micro-interferometers, on plasmonic effects in fibers and on multimode interference in a large spectrum of standard and microstructured optical fibers. Full article
(This article belongs to the Special Issue State-of-the-Art Sensors Technology in Portugal)
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Open AccessArticle License Plate Recognition Algorithm for Passenger Cars in Chinese Residential Areas
Sensors 2012, 12(6), 8355-8370; https://doi.org/10.3390/s120608355
Received: 20 March 2012 / Revised: 7 June 2012 / Accepted: 7 June 2012 / Published: 15 June 2012
Cited by 19 | Viewed by 3471 | PDF Full-text (783 KB) | HTML Full-text | XML Full-text
Abstract
This paper presents a solution for the license plate recognition problem in residential community administrations in China. License plate images are pre-processed through gradation, middle value filters and edge detection. In the license plate localization module the number of edge points, the length [...] Read more.
This paper presents a solution for the license plate recognition problem in residential community administrations in China. License plate images are pre-processed through gradation, middle value filters and edge detection. In the license plate localization module the number of edge points, the length of license plate area and the number of each line of edge points are used for localization. In the recognition module, the paper applies a statistical character method combined with a structure character method to obtain the characters. In addition, more models and template library for the characters which have less difference between each other are built. A character classifier is designed and a fuzzy recognition method is proposed based on the fuzzy decision-making method. Experiments show that the recognition accuracy rate is up to 92%. Full article
(This article belongs to the Section Physical Sensors)
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Open AccessArticle A Miniature Integrated Multimodal Sensor for Measuring pH, EC and Temperature for Precision Agriculture
Sensors 2012, 12(6), 8338-8354; https://doi.org/10.3390/s120608338
Received: 30 April 2012 / Revised: 30 May 2012 / Accepted: 1 June 2012 / Published: 15 June 2012
Cited by 24 | Viewed by 4875 | PDF Full-text (1140 KB) | HTML Full-text | XML Full-text
Abstract
Making several simultaneous measurements with different kinds of sensors at the same location in a solution is difficult because of crosstalk between the sensors. In addition, because the conditions at different locations in plant beds differ, in situ measurements in agriculture need to [...] Read more.
Making several simultaneous measurements with different kinds of sensors at the same location in a solution is difficult because of crosstalk between the sensors. In addition, because the conditions at different locations in plant beds differ, in situ measurements in agriculture need to be done in small localized areas. We have fabricated a multimodal sensor on a small Si chip in which a pH sensor was integrated with electrical conductivity (EC) and temperature sensors. An ISFET with a Si3N4 membrane was used for the pH sensor. For the EC sensor, the electrical conductivity between platinum electrodes was measured, and the temperature sensor was a p-n junction diode. These are some of the most important measurements required for controlling the conditions in plant beds. The multimodal sensor can be inserted into a plant bed for in situ monitoring. To confirm the absence of crosstalk between the sensors, we made simultaneous measurements of pH, EC, and temperature of a pH buffer solution in a plant bed. When the solution was diluted with hot or cold water, the real time measurements showed changes to the EC and temperature, but no change in pH. We also demonstrated that our sensor was capable of simultaneous in situ measurements in rock wool without being affected by crosstalk. Full article
(This article belongs to the Special Issue Ultra-Small Sensor Systems and Components)
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Open AccessReview Diagnostic Devices for Isothermal Nucleic Acid Amplification
Sensors 2012, 12(6), 8319-8337; https://doi.org/10.3390/s120608319
Received: 2 May 2012 / Revised: 29 May 2012 / Accepted: 7 June 2012 / Published: 14 June 2012
Cited by 62 | Viewed by 5912 | PDF Full-text (3895 KB) | HTML Full-text | XML Full-text
Abstract
Since the development of the polymerase chain reaction (PCR) technique, genomic information has been retrievable from lesser amounts of DNA than previously possible. PCR-based amplifications require high-precision instruments to perform temperature cycling reactions; further, they are cumbersome for routine clinical use. However, the [...] Read more.
Since the development of the polymerase chain reaction (PCR) technique, genomic information has been retrievable from lesser amounts of DNA than previously possible. PCR-based amplifications require high-precision instruments to perform temperature cycling reactions; further, they are cumbersome for routine clinical use. However, the use of isothermal approaches can eliminate many complications associated with thermocycling. The application of diagnostic devices for isothermal DNA amplification has recently been studied extensively. In this paper, we describe the basic concepts of several isothermal amplification approaches and review recent progress in diagnostic device development. Full article
(This article belongs to the Special Issue Biomarkers and Nanosensors: New Approaches for Biology and Medicine)
Open AccessArticle Intelligent Lead: A Novel HRI Sensor for Guide Robots
Sensors 2012, 12(6), 8301-8318; https://doi.org/10.3390/s120608301
Received: 23 May 2012 / Revised: 6 June 2012 / Accepted: 6 June 2012 / Published: 14 June 2012
Cited by 20 | Viewed by 3562 | PDF Full-text (1313 KB) | HTML Full-text | XML Full-text
Abstract
This paper addresses the introduction of a new Human Robot Interaction (HRI) sensor for guide robots. Guide robots for geriatric patients or the visually impaired should follow user’s control command, keeping a certain desired distance allowing the user to work freely. Therefore, it [...] Read more.
This paper addresses the introduction of a new Human Robot Interaction (HRI) sensor for guide robots. Guide robots for geriatric patients or the visually impaired should follow user’s control command, keeping a certain desired distance allowing the user to work freely. Therefore, it is necessary to acquire control commands and a user’s position on a real-time basis. We suggest a new sensor fusion system to achieve this objective and we will call this sensor the “intelligent lead”. The objective of the intelligent lead is to acquire a stable distance from the user to the robot, speed-control volume and turn-control volume, even when the robot platform with the intelligent lead is shaken on uneven ground. In this paper we explain a precise Extended Kalman Filter (EKF) procedure for this. The intelligent lead physically consists of a Kinect sensor, the serial linkage attached with eight rotary encoders, and an IMU (Inertial Measurement Unit) and their measurements are fused by the EKF. A mobile robot was designed to test the performance of the proposed sensor system. After installing the intelligent lead in the mobile robot, several tests are conducted to verify that the mobile robot with the intelligent lead is capable of achieving its goal points while maintaining the appropriate distance between the robot and the user. The results show that we can use the intelligent lead proposed in this paper as a new HRI sensor joined a joystick and a distance measure in the mobile environments such as the robot and the user are moving at the same time. Full article
(This article belongs to the Section Physical Sensors)
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Open AccessReview Atomic Force Microscopy as a Tool Applied to Nano/Biosensors
Sensors 2012, 12(6), 8278-8300; https://doi.org/10.3390/s120608278
Received: 5 April 2012 / Revised: 1 June 2012 / Accepted: 5 June 2012 / Published: 14 June 2012
Cited by 33 | Viewed by 4107 | PDF Full-text (731 KB) | HTML Full-text | XML Full-text
Abstract
This review article discusses and documents the basic concepts and principles of nano/biosensors. More specifically, we comment on the use of Chemical Force Microscopy (CFM) to study various aspects of architectural and chemical design details of specific molecules and polymers and its influence [...] Read more.
This review article discusses and documents the basic concepts and principles of nano/biosensors. More specifically, we comment on the use of Chemical Force Microscopy (CFM) to study various aspects of architectural and chemical design details of specific molecules and polymers and its influence on the control of chemical interactions between the Atomic Force Microscopy (AFM) tip and the sample. This technique is based on the fabrication of nanomechanical cantilever sensors (NCS) and microcantilever-based biosensors (MC-B), which can provide, depending on the application, rapid, sensitive, simple and low-cost in situ detection. Besides, it can provide high repeatability and reproducibility. Here, we review the applications of CFM through some application examples which should function as methodological questions to understand and transform this tool into a reliable source of data. This section is followed by a description of the theoretical principle and usage of the functionalized NCS and MC-B technique in several fields, such as agriculture, biotechnology and immunoassay. Finally, we hope this review will help the reader to appreciate how important the tools CFM, NCS and MC-B are for characterization and understanding of systems on the atomic scale. Full article
(This article belongs to the Section Chemical Sensors)
Open AccessArticle Experimental Artifacts for Morphological Tweaking of Chemical Sensor Materials: Studies on ZnO
Sensors 2012, 12(6), 8259-8277; https://doi.org/10.3390/s120608259
Received: 2 May 2012 / Revised: 29 May 2012 / Accepted: 6 June 2012 / Published: 13 June 2012
Cited by 5 | Viewed by 3947 | PDF Full-text (1864 KB) | HTML Full-text | XML Full-text
Abstract
Sensing mechanisms of gases on solid structures are predominantly surface-dominated. Benign surface features in terms of small grain size, high aspect ratio, large surface area and open and connected porosity, are required to realize a successful sensor material. Such morphological artifacts are a [...] Read more.
Sensing mechanisms of gases on solid structures are predominantly surface-dominated. Benign surface features in terms of small grain size, high aspect ratio, large surface area and open and connected porosity, are required to realize a successful sensor material. Such morphological artifacts are a function of the fabrication and processing techniques employed. In this paper, we describe the fabrication of monoshaped and monosized zinc oxide (ZnO) particles by a homogeneous precipitation method, using urea and/or hexmethyltetraamine as the reductant. The effect of operating conditions and experimental variables, such as the relative concentration of the precursors, temperature, and the aging time on the morphology of the resulting particles was studied systematically. These experimental parameters were optimized in order to achieve particles of uniform morphology and of narrow size distribution. Some of these particles were employed for the detection of ammonia gas at room temperature. Full article
(This article belongs to the Special Issue Sensing at the Nano-Scale: Chemical and Bio-Sensing)
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Open AccessArticle An Indoor Navigation System for the Visually Impaired
Sensors 2012, 12(6), 8236-8258; https://doi.org/10.3390/s120608236
Received: 27 April 2012 / Revised: 29 May 2012 / Accepted: 31 May 2012 / Published: 13 June 2012
Cited by 71 | Viewed by 4291 | PDF Full-text (873 KB) | HTML Full-text | XML Full-text
Abstract
Navigation in indoor environments is highly challenging for the severely visually impaired, particularly in spaces visited for the first time. Several solutions have been proposed to deal with this challenge. Although some of them have shown to be useful in real scenarios, they [...] Read more.
Navigation in indoor environments is highly challenging for the severely visually impaired, particularly in spaces visited for the first time. Several solutions have been proposed to deal with this challenge. Although some of them have shown to be useful in real scenarios, they involve an important deployment effort or use artifacts that are not natural for blind users. This paper presents an indoor navigation system that was designed taking into consideration usability as the quality requirement to be maximized. This solution enables one to identify the position of a person and calculates the velocity and direction of his movements. Using this information, the system determines the user’s trajectory, locates possible obstacles in that route, and offers navigation information to the user. The solution has been evaluated using two experimental scenarios. Although the results are still not enough to provide strong conclusions, they indicate that the system is suitable to guide visually impaired people through an unknown built environment. Full article
Open AccessArticle A Fast MEANSHIFT Algorithm-Based Target Tracking System
Sensors 2012, 12(6), 8218-8235; https://doi.org/10.3390/s120608218
Received: 13 April 2012 / Revised: 9 May 2012 / Accepted: 22 May 2012 / Published: 13 June 2012
Cited by 5 | Viewed by 3118 | PDF Full-text (3880 KB) | HTML Full-text | XML Full-text
Abstract
Tracking moving targets in complex scenes using an active video camera is a challenging task. Tracking accuracy and efficiency are two key yet generally incompatible aspects of a Target Tracking System (TTS). A compromise scheme will be studied in this paper. A fast [...] Read more.
Tracking moving targets in complex scenes using an active video camera is a challenging task. Tracking accuracy and efficiency are two key yet generally incompatible aspects of a Target Tracking System (TTS). A compromise scheme will be studied in this paper. A fast mean-shift-based Target Tracking scheme is designed and realized, which is robust to partial occlusion and changes in object appearance. The physical simulation shows that the image signal processing speed is > 50 frame/s. Full article
(This article belongs to the Section Physical Sensors)
Open AccessArticle Open-WiSe: A Solar Powered Wireless Sensor Network Platform
Sensors 2012, 12(6), 8204-8217; https://doi.org/10.3390/s120608204
Received: 1 May 2012 / Revised: 4 June 2012 / Accepted: 8 June 2012 / Published: 13 June 2012
Cited by 17 | Viewed by 4079 | PDF Full-text (738 KB) | HTML Full-text | XML Full-text
Abstract
Because battery-powered nodes are required in wireless sensor networks and energy consumption represents an important design consideration, alternate energy sources are needed to provide more effective and optimal function. The main goal of this work is to present an energy harvesting wireless sensor [...] Read more.
Because battery-powered nodes are required in wireless sensor networks and energy consumption represents an important design consideration, alternate energy sources are needed to provide more effective and optimal function. The main goal of this work is to present an energy harvesting wireless sensor network platform, the Open Wireless Sensor node (WiSe). The design and implementation of the solar powered wireless platform is described including the hardware architecture, firmware, and a POSIX Real-Time Kernel. A sleep and wake up strategy was implemented to prolong the lifetime of the wireless sensor network. This platform was developed as a tool for researchers investigating Wireless sensor network or system integrators. Full article
Open AccessArticle A Novel Sensor for Monitoring of Iron(III) Ions Based on Porphyrins
Sensors 2012, 12(6), 8193-8203; https://doi.org/10.3390/s120608193
Received: 9 April 2012 / Revised: 27 May 2012 / Accepted: 8 June 2012 / Published: 13 June 2012
Cited by 39 | Viewed by 3393 | PDF Full-text (202 KB) | HTML Full-text | XML Full-text
Abstract
Three A3B porphyrins with mixed carboxy-, phenoxy-, pyridyl- and dimethoxy-substituent functionalization on the meso-phenyl groups were obtained by multicomponent synthesis, fully characterized and used as ionophores for preparing PVC-based membrane sensors selective to iron(III). The membranes have an ionophore:PVC:plasticizer composition [...] Read more.
Three A3B porphyrins with mixed carboxy-, phenoxy-, pyridyl- and dimethoxy-substituent functionalization on the meso-phenyl groups were obtained by multicomponent synthesis, fully characterized and used as ionophores for preparing PVC-based membrane sensors selective to iron(III). The membranes have an ionophore:PVC:plasticizer composition ratio of 1:33:66. Sodium tetraphenylborate was used as additive (20 mol% relative to ionophore). The performance characteristics (linear concentration range, slope and selectivity) of the sensors were investigated. The best results were obtained for the membrane based on 5-(4-carboxyphenyl)-10,15,20-tris(4-phenoxyphenyl)-porphyrin plasticized with bis(2-ethylhexyl)sebacate, in a linear range from 1 × 10−7–1 × 10−1 M with a slope of 21.6 mV/decade. The electrode showed high selectivity with respect to alkaline and heavy metal ions and a response time of 20 s. The influence of pH on the sensor response was studied. The sensor was used for a period of six weeks and the utility has been tested for the quantitative determination of Fe(III) in recovered solutions from spent lithium ion batteries and for the quantitative determination of Fe(III) in tap water samples. Full article
(This article belongs to the Section Chemical Sensors)
Open AccessArticle Long-Term Outdoor Reliability Assessment of a Wireless Unit for Air-Quality Monitoring Based on Nanostructured Films Integrated on Micromachined Platforms
Sensors 2012, 12(6), 8176-8192; https://doi.org/10.3390/s120608176
Received: 15 March 2012 / Revised: 31 May 2012 / Accepted: 8 June 2012 / Published: 13 June 2012
Cited by 6 | Viewed by 3375 | PDF Full-text (1254 KB) | HTML Full-text | XML Full-text
Abstract
We have fabricated and tested in long-term field operating conditions a wireless unit for outdoor air quality monitoring. The unit is equipped with two multiparametric sensors, one miniaturized thermo-hygrometer, front-end analogical and digital electronics, and an IEEE 802.15.4 based module for wireless data [...] Read more.
We have fabricated and tested in long-term field operating conditions a wireless unit for outdoor air quality monitoring. The unit is equipped with two multiparametric sensors, one miniaturized thermo-hygrometer, front-end analogical and digital electronics, and an IEEE 802.15.4 based module for wireless data transmission. Micromachined platforms were functionalized with nanoporous metal-oxides to obtain multiparametric sensors, hosting gas-sensitive, anemometric and temperature transducers. Nanoporous metal-oxide layer was directly deposited on gas sensing regions of micromachined platform batches by hard-mask patterned supersonic cluster beam deposition. An outdoor, roadside experiment was arranged in downtown Milan (Italy), where one wireless sensing unit was continuously operated side by side with standard gas chromatographic instrumentation for air quality measurements. By means of a router PC, data from sensing unit and other instrumentation were collected, merged, and sent to a remote data storage server, through an UMTS device. The whole-system robustness as well as sensor dataset characteristics were continuously characterized over a run-time period of 18 months. Full article
(This article belongs to the Section Physical Sensors)
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Open AccessArticle Improved Iterative Calibration for Triaxial Accelerometers Based on the Optimal Observation
Sensors 2012, 12(6), 8157-8175; https://doi.org/10.3390/s120608157
Received: 2 April 2012 / Revised: 25 May 2012 / Accepted: 31 May 2012 / Published: 12 June 2012
Cited by 6 | Viewed by 2967 | PDF Full-text (596 KB) | HTML Full-text | XML Full-text
Abstract
This paper presents an improved iterative nonlinear calibration method in the gravitational field for both low-grade and high-grade triaxial accelerometers. This calibration method assumes the probability density function of a Gaussian distribution for the raw outputs of triaxial accelerometers. A nonlinear criterion function [...] Read more.
This paper presents an improved iterative nonlinear calibration method in the gravitational field for both low-grade and high-grade triaxial accelerometers. This calibration method assumes the probability density function of a Gaussian distribution for the raw outputs of triaxial accelerometers. A nonlinear criterion function is derived as the maximum likelihood estimation for the calibration parameters and inclination vectors, which is solved by the iterative estimation. First, the calibration parameters, including the scale factors, misalignments, biases and squared coefficients are estimated by the linear least squares method according to the multi-position raw outputs of triaxial accelerometers and the initial inclination vectors. Second, the sequence quadric program method is utilized to solve the nonlinear constrained optimization to update the inclination vectors according to the estimated calibration parameters and raw outputs of the triaxial accelerometers. The initial inclination vectors are supplied by normalizing raw outputs of triaxial accelerometers at different positions without any a priori knowledge. To overcome the imperfections of models, the optimal observation scheme is designed according to some maximum sensitivity principle. Simulation and experiments show good estimation accuracy for calibration parameters and inclination vectors. Full article
(This article belongs to the Section Physical Sensors)
Open AccessArticle Accuracy and Precision of Equine Gait Event Detection during Walking with Limb and Trunk Mounted Inertial Sensors
Sensors 2012, 12(6), 8145-8156; https://doi.org/10.3390/s120608145
Received: 12 April 2012 / Revised: 4 June 2012 / Accepted: 7 June 2012 / Published: 12 June 2012
Cited by 28 | Viewed by 5366 | PDF Full-text (337 KB) | HTML Full-text | XML Full-text | Supplementary Files
Abstract
The increased variations of temporal gait events when pathology is present are good candidate features for objective diagnostic tests. We hypothesised that the gait events hoof-on/off and stance can be detected accurately and precisely using features from trunk and distal limb-mounted Inertial Measurement [...] Read more.
The increased variations of temporal gait events when pathology is present are good candidate features for objective diagnostic tests. We hypothesised that the gait events hoof-on/off and stance can be detected accurately and precisely using features from trunk and distal limb-mounted Inertial Measurement Units (IMUs). Four IMUs were mounted on the distal limb and five IMUs were attached to the skin over the dorsal spinous processes at the withers, fourth lumbar vertebrae and sacrum as well as left and right tuber coxae. IMU data were synchronised to a force plate array and a motion capture system. Accuracy (bias) and precision (SD of bias) was calculated to compare force plate and IMU timings for gait events. Data were collected from seven horses. One hundred and twenty three (123) front limb steps were analysed; hoof-on was detected with a bias (SD) of −7 (23) ms, hoof-off with 0.7 (37) ms and front limb stance with −0.02 (37) ms. A total of 119 hind limb steps were analysed; hoof-on was found with a bias (SD) of −4 (25) ms, hoof-off with 6 (21) ms and hind limb stance with 0.2 (28) ms. IMUs mounted on the distal limbs and sacrum can detect gait events accurately and precisely. Full article
(This article belongs to the Section Physical Sensors)
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Open AccessArticle Novel Platform Development Using an Assembly of Carbon Nanotube, Nanogold and Immobilized RNA Capture Element towards Rapid, Selective Sensing of Bacteria
Sensors 2012, 12(6), 8135-8144; https://doi.org/10.3390/s120608135
Received: 1 May 2012 / Revised: 29 May 2012 / Accepted: 1 June 2012 / Published: 12 June 2012
Cited by 16 | Viewed by 4407 | PDF Full-text (871 KB) | HTML Full-text | XML Full-text
Abstract
This study examines the creation of a nano-featured biosensor platform designed for the rapid and selective detection of the bacterium Escherichia coli. The foundation of this sensor is carbon nanotubes decorated with gold nanoparticles that are modified with a specific, surface adherent [...] Read more.
This study examines the creation of a nano-featured biosensor platform designed for the rapid and selective detection of the bacterium Escherichia coli. The foundation of this sensor is carbon nanotubes decorated with gold nanoparticles that are modified with a specific, surface adherent ribonucleiuc acid (RNA) sequence element. The multi-step sensor assembly was accomplished by growing carbon nanotubes on a graphite substrate, the direct synthesis of gold nanoparticles on the nanotube surface, and the attachment of thiolated RNA to the bound nanoparticles. The application of the compounded nano-materials for sensor development has the distinct advantage of retaining the electrical behavior property of carbon nanotubes and, through the gold nanoparticles, incorporating an increased surface area for additional analyte attachment sites, thus increasing sensitivity. We successfully demonstrated that the coating of gold nanoparticles with a selective RNA sequence increased the capture of E. coli by 189% when compared to uncoated particles. The approach to sensor formation detailed in this study illustrates the great potential of unique composite structures in the development of a multi-array, electrochemical sensor for the fast and sensitive detection of pathogens. Full article
(This article belongs to the Special Issue Nano-Biosensors)
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Open AccessArticle Process-in-Network: A Comprehensive Network Processing Approach
Sensors 2012, 12(6), 8112-8134; https://doi.org/10.3390/s120608112
Received: 23 April 2012 / Revised: 30 May 2012 / Accepted: 4 June 2012 / Published: 12 June 2012
Cited by 1 | Viewed by 3216 | PDF Full-text (741 KB) | HTML Full-text | XML Full-text
Abstract
A solid and versatile communications platform is very important in modern Ambient Intelligence (AmI) applications, which usually require the transmission of large amounts of multimedia information over a highly heterogeneous network. This article focuses on the concept of Process-in-Network (PIN), which is defined [...] Read more.
A solid and versatile communications platform is very important in modern Ambient Intelligence (AmI) applications, which usually require the transmission of large amounts of multimedia information over a highly heterogeneous network. This article focuses on the concept of Process-in-Network (PIN), which is defined as the possibility that the network processes information as it is being transmitted, and introduces a more comprehensive approach than current network processing technologies. PIN can take advantage of waiting times in queues of routers, idle processing capacity in intermediate nodes, and the information that passes through the network. Full article
Open AccessArticle Novel Biochip Platform for Nucleic Acid Analysis
Sensors 2012, 12(6), 8100-8111; https://doi.org/10.3390/s120608100
Received: 25 April 2012 / Revised: 21 May 2012 / Accepted: 31 May 2012 / Published: 11 June 2012
Cited by 19 | Viewed by 6759 | PDF Full-text (938 KB) | HTML Full-text | XML Full-text | Supplementary Files
Abstract
This manuscript describes the use of a novel biochip platform for the rapid analysis/identification of nucleic acids, including DNA and microRNAs, with very high specificity. This approach combines a unique dynamic chemistry approach for nucleic acid testing and analysis developed by DestiNA Genomics [...] Read more.
This manuscript describes the use of a novel biochip platform for the rapid analysis/identification of nucleic acids, including DNA and microRNAs, with very high specificity. This approach combines a unique dynamic chemistry approach for nucleic acid testing and analysis developed by DestiNA Genomics with the STMicroelectronics In-Check platform, which comprises two microfluidic optimized and independent PCR reaction chambers, and a sequential microarray area for nucleic acid capture and identification by fluorescence. With its compact bench-top “footprint” requiring only a single technician to operate, the biochip system promises to transform and expand routine clinical diagnostic testing and screening for genetic diseases, cancers, drug toxicology and heart disease, as well as employment in the emerging companion diagnostics market. Full article
(This article belongs to the Special Issue Biomarkers and Nanosensors: New Approaches for Biology and Medicine)
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Open AccessArticle Robust Feedback Zoom Tracking for Digital Video Surveillance
Sensors 2012, 12(6), 8073-8099; https://doi.org/10.3390/s120608073
Received: 9 April 2012 / Revised: 31 May 2012 / Accepted: 1 June 2012 / Published: 11 June 2012
Cited by 3 | Viewed by 3562 | PDF Full-text (3480 KB) | HTML Full-text | XML Full-text
Abstract
Zoom tracking is an important function in video surveillance, particularly in traffic management and security monitoring. It involves keeping an object of interest in focus during the zoom operation. Zoom tracking is typically achieved by moving the zoom and focus motors in lenses [...] Read more.
Zoom tracking is an important function in video surveillance, particularly in traffic management and security monitoring. It involves keeping an object of interest in focus during the zoom operation. Zoom tracking is typically achieved by moving the zoom and focus motors in lenses following the so-called “trace curve”, which shows the in-focus motor positions versus the zoom motor positions for a specific object distance. The main task of a zoom tracking approach is to accurately estimate the trace curve for the specified object. Because a proportional integral derivative (PID) controller has historically been considered to be the best controller in the absence of knowledge of the underlying process and its high-quality performance in motor control, in this paper, we propose a novel feedback zoom tracking (FZT) approach based on the geometric trace curve estimation and PID feedback controller. The performance of this approach is compared with existing zoom tracking methods in digital video surveillance. The real-time implementation results obtained on an actual digital video platform indicate that the developed FZT approach not only solves the traditional one-to-many mapping problem without pre-training but also improves the robustness for tracking moving or switching objects which is the key challenge in video surveillance. Full article
(This article belongs to the Section Physical Sensors)
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Open AccessArticle Electronic Nose Based on Independent Component Analysis Combined with Partial Least Squares and Artificial Neural Networks for Wine Prediction
Sensors 2012, 12(6), 8055-8072; https://doi.org/10.3390/s120608055
Received: 10 April 2012 / Revised: 25 May 2012 / Accepted: 5 June 2012 / Published: 11 June 2012
Cited by 25 | Viewed by 4743 | PDF Full-text (2473 KB) | HTML Full-text | XML Full-text
Abstract
The aim of this work is to propose an alternative way for wine classification and prediction based on an electronic nose (e-nose) combined with Independent Component Analysis (ICA) as a dimensionality reduction technique, Partial Least Squares (PLS) to predict sensorial descriptors and Artificial [...] Read more.
The aim of this work is to propose an alternative way for wine classification and prediction based on an electronic nose (e-nose) combined with Independent Component Analysis (ICA) as a dimensionality reduction technique, Partial Least Squares (PLS) to predict sensorial descriptors and Artificial Neural Networks (ANNs) for classification purpose. A total of 26 wines from different regions, varieties and elaboration processes have been analyzed with an e-nose and tasted by a sensory panel. Successful results have been obtained in most cases for prediction and classification. Full article
Open AccessArticle On the Use of Sensor Fusion to Reduce the Impact of Rotational and Additive Noise in Human Activity Recognition
Sensors 2012, 12(6), 8039-8054; https://doi.org/10.3390/s120608039
Received: 19 March 2012 / Revised: 5 June 2012 / Accepted: 6 June 2012 / Published: 11 June 2012
Cited by 27 | Viewed by 3635 | PDF Full-text (561 KB) | HTML Full-text | XML Full-text
Abstract
The main objective of fusion mechanisms is to increase the individual reliability of the systems through the use of the collectivity knowledge. Moreover, fusion models are also intended to guarantee a certain level of robustness. This is particularly required for problems such as [...] Read more.
The main objective of fusion mechanisms is to increase the individual reliability of the systems through the use of the collectivity knowledge. Moreover, fusion models are also intended to guarantee a certain level of robustness. This is particularly required for problems such as human activity recognition where runtime changes in the sensor setup seriously disturb the reliability of the initial deployed systems. For commonly used recognition systems based on inertial sensors, these changes are primarily characterized as sensor rotations, displacements or faults related to the batteries or calibration. In this work we show the robustness capabilities of a sensor-weighted fusion model when dealing with such disturbances under different circumstances. Using the proposed method, up to 60% outperformance is obtained when a minority of the sensors are artificially rotated or degraded, independent of the level of disturbance (noise) imposed. These robustness capabilities also apply for any number of sensors affected by a low to moderate noise level. The presented fusion mechanism compensates the poor performance that otherwise would be obtained when just a single sensor is considered. Full article
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Open AccessArticle An Annular Mechanical Temperature Compensation Structure for Gas-Sealed Capacitive Pressure Sensor
Sensors 2012, 12(6), 8026-8038; https://doi.org/10.3390/s120608026
Received: 24 April 2012 / Revised: 2 May 2012 / Accepted: 4 June 2012 / Published: 11 June 2012
Cited by 8 | Viewed by 3775 | PDF Full-text (1391 KB) | HTML Full-text | XML Full-text
Abstract
A novel gas-sealed capacitive pressure sensor with a temperature compensation structure is reported. The pressure sensor is sealed by Au-Au diffusion bonding under a nitrogen ambient with a pressure of 100 kPa and integrated with a platinum resistor-based temperature sensor for human activity [...] Read more.
A novel gas-sealed capacitive pressure sensor with a temperature compensation structure is reported. The pressure sensor is sealed by Au-Au diffusion bonding under a nitrogen ambient with a pressure of 100 kPa and integrated with a platinum resistor-based temperature sensor for human activity monitoring applications. The capacitance-pressure and capacitance-temperature characteristics of the gas-sealed capacitive pressure sensor without temperature compensation structure are calculated. It is found by simulation that a ring-shaped structure on the diaphragm of the pressure sensor can mechanically suppress the thermal expansion effect of the sealed gas in the cavity. Pressure sensors without/with temperature compensation structures are fabricated and measured. Through measured results, it is verified that the calculation model is accurate. Using the compensation structures with a 900 μm inner radius, the measured temperature coefficient is much reduced as compared to that of the pressure sensor without compensation. The sensitivities of the pressure sensor before and after compensation are almost the same in the pressure range from 80 kPa to 100 kPa. Full article
(This article belongs to the Section Physical Sensors)
Open AccessArticle Selective Detection of NO2 Using Cr-Doped CuO Nanorods
Sensors 2012, 12(6), 8013-8025; https://doi.org/10.3390/s120608013
Received: 24 April 2012 / Revised: 18 May 2012 / Accepted: 1 June 2012 / Published: 11 June 2012
Cited by 35 | Viewed by 3584 | PDF Full-text (797 KB) | HTML Full-text | XML Full-text
Abstract
CuO nanosheets, Cr-doped CuO nanosheets, and Cr-doped CuO nanorods were prepared by heating a slurry containing Cu-hydroxide/Cr-hydroxide. Their responses to 100 ppm NO2, C2H5OH, NH3, trimethylamine, C3H8, and CO were measured. [...] Read more.
CuO nanosheets, Cr-doped CuO nanosheets, and Cr-doped CuO nanorods were prepared by heating a slurry containing Cu-hydroxide/Cr-hydroxide. Their responses to 100 ppm NO2, C2H5OH, NH3, trimethylamine, C3H8, and CO were measured. For 2.2 at% Cr-doped CuO nanorods, the response (Ra/Rg, Ra: resistance in air, Rg: resistance in gas) to 100 ppm NO2 was 134.2 at 250 °C, which was significantly higher than that of pure CuO nano-sheets (Ra/Rg = 7.5) and 0.76 at% Cr-doped CuO nanosheets (Ra/Rg = 19.9). In addition, the sensitivity for NO2 was also markedly enhanced by Cr doping. Highly sensitive and selective detection of NO2 in 2.2 at% Cr-doped CuO nanorods is explained in relation to Cr-doping induced changes in donor density, morphology, and catalytic effects. Full article
(This article belongs to the Section Chemical Sensors)
Open AccessArticle Compiler Optimizations as a Countermeasure against Side-Channel Analysis in MSP430-Based Devices
Sensors 2012, 12(6), 7994-8012; https://doi.org/10.3390/s120607994
Received: 16 May 2012 / Revised: 4 June 2012 / Accepted: 4 June 2012 / Published: 8 June 2012
Cited by 1 | Viewed by 3364 | PDF Full-text (2125 KB) | HTML Full-text | XML Full-text
Abstract
Ambient Intelligence (AmI) requires devices everywhere, dynamic and massively distributed networks of low-cost nodes that, among other data, manage private information or control restricted operations. MSP430, a 16-bit microcontroller, is used in WSN platforms, as the TelosB. Physical access to devices cannot be [...] Read more.
Ambient Intelligence (AmI) requires devices everywhere, dynamic and massively distributed networks of low-cost nodes that, among other data, manage private information or control restricted operations. MSP430, a 16-bit microcontroller, is used in WSN platforms, as the TelosB. Physical access to devices cannot be restricted, so attackers consider them a target of their malicious attacks in order to obtain access to the network. Side-channel analysis (SCA) easily exploits leakages from the execution of encryption algorithms that are dependent on critical data to guess the key value. In this paper we present an evaluation framework that facilitates the analysis of the effects of compiler and backend optimizations on the resistance against statistical SCA. We propose an optimization-based software countermeasure that can be used in current low-cost devices to radically increase resistance against statistical SCA, analyzed with the new framework. Full article
Open AccessArticle Reliable Finite Frequency Filter Design for Networked Control Systems with Sensor Faults
Sensors 2012, 12(6), 7975-7993; https://doi.org/10.3390/s120607975
Received: 6 April 2012 / Revised: 17 May 2012 / Accepted: 21 May 2012 / Published: 8 June 2012
Viewed by 2815 | PDF Full-text (154 KB) | HTML Full-text | XML Full-text
Abstract
This paper is concerned with the reliable finite frequency filter design for networked control systems (NCSs) subject to quantization and data missing. Taking into account quantization, possible data missing and sensor stuck faults, NCSs are modeled in the framework of discrete time-delay switched [...] Read more.
This paper is concerned with the reliable finite frequency filter design for networked control systems (NCSs) subject to quantization and data missing. Taking into account quantization, possible data missing and sensor stuck faults, NCSs are modeled in the framework of discrete time-delay switched systems, and the finite frequency l2 gain is adopted for the filter design of discrete time-delay switched systems, which is converted into a set of linear matrix inequality (LMI) conditions. By the virtues of the derived conditions, a procedure of reliable filter synthesis is presented. Further, the filter gains are characterized in terms of solutions to a convex optimization problem which can be solved by using the semi-definite programme method. Finally, an example is given to illustrate the effectiveness of the proposed method. Full article
(This article belongs to the Section Physical Sensors)
Open AccessArticle Synergistic Effects in the Gas Sensitivity of Polypyrrole/Single Wall Carbon Nanotube Composites
Sensors 2012, 12(6), 7965-7974; https://doi.org/10.3390/s120607965
Received: 19 April 2012 / Revised: 24 May 2012 / Accepted: 25 May 2012 / Published: 8 June 2012
Cited by 41 | Viewed by 3517 | PDF Full-text (681 KB) | HTML Full-text | XML Full-text
Abstract
Polypyrrole/single wall carbon nanotube composites were synthesized by in-situ chemical polymerization using pyrrole (PPy) as precursor and single wall carbon nanotubes (SWNTs) as additive component. Electron microscope images reveal that SWNTs component acts as nucleation sites for PPy growth in the form of [...] Read more.
Polypyrrole/single wall carbon nanotube composites were synthesized by in-situ chemical polymerization using pyrrole (PPy) as precursor and single wall carbon nanotubes (SWNTs) as additive component. Electron microscope images reveal that SWNTs component acts as nucleation sites for PPy growth in the form of spherical and cylindrical core-shell structures. The SWNTs/PPy core-shell results in thin n-p junctions which modify the PPy bandgap and reduce the work function of electrons. As a result of the strong coupling, Raman and IR spectra show that the PPy undergoes a transition from polaron to bipolaron state, i.e., indicating an increase in the conductivity. In the UV-Vis spectra, the 340 nm adsorption band (π*-π transition) exhibits a red shift, while the 460 nm adsorption band (bipolaron transition) experiences a blue shift indicating a change in electronic structure and a relocation of polaron levels in the band gap of PPy. The modification in PPy electronic structure brings in a synergistic effect in sensing feature. Upon exposure to oxygen (an oxidizing agent) and NH3 gas (a reducing agent), the PPy/SWNTs nanocomposite shows an enhancement in sensitivity exceeding ten folds in comparison with those of PPy or SWNTs. Full article
(This article belongs to the Section Chemical Sensors)
Open AccessArticle Palmprint Recognition across Different Devices
Sensors 2012, 12(6), 7938-7964; https://doi.org/10.3390/s120607938
Received: 17 April 2012 / Revised: 21 May 2012 / Accepted: 22 May 2012 / Published: 8 June 2012
Cited by 18 | Viewed by 3290 | PDF Full-text (1615 KB) | HTML Full-text | XML Full-text
Abstract
In this paper, the problem of Palmprint Recognition Across Different Devices (PRADD) is investigated, which has not been well studied so far. Since there is no publicly available PRADD image database, we created a non-contact PRADD image database containing 12,000 grayscale captured from [...] Read more.
In this paper, the problem of Palmprint Recognition Across Different Devices (PRADD) is investigated, which has not been well studied so far. Since there is no publicly available PRADD image database, we created a non-contact PRADD image database containing 12,000 grayscale captured from 100 subjects using three devices, i.e., one digital camera and two smart-phones. Due to the non-contact image acquisition used, rotation and scale changes between different images captured from a same palm are inevitable. We propose a robust method to calculate the palm width, which can be effectively used for scale normalization of palmprints. On this PRADD image database, we evaluate the recognition performance of three different methods, i.e., subspace learning method, correlation method, and orientation coding based method, respectively. Experiments results show that orientation coding based methods achieved promising recognition performance for PRADD. Full article
(This article belongs to the Special Issue Hand-Based Biometrics Sensors and Systems)
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