Sensors

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Open AccessEditorial

Acknowledgement to Reviewers of Sensors in 2013

by Sensors Editorial Office

Sensors 2014, 14(2), 3797-3824; https://doi.org/10.3390/s140203797 - 25 Feb 2014

Cited by 1 | Viewed by 10450

The editors of Sensors would like to express their sincere gratitude to the following reviewers for assessing manuscripts in 2013. [...] Full article

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Open AccessArticle

Implementation and Performance of a GPS/INS Tightly Coupled Assisted PLL Architecture Using MEMS Inertial Sensors

by Youssef Tawk, Phillip Tomé, Cyril Botteron, Yannick Stebler and Pierre-André Farine

Sensors 2014, 14(2), 3768-3796; https://doi.org/10.3390/s140203768 - 24 Feb 2014

Cited by 40 | Viewed by 9093

Abstract

The use of global navigation satellite system receivers for navigation still presents many challenges in urban canyon and indoor environments, where satellite availability is typically reduced and received signals are attenuated. To improve the navigation performance in such environments, several enhancement methods can [...] Read more.

The use of global navigation satellite system receivers for navigation still presents many challenges in urban canyon and indoor environments, where satellite availability is typically reduced and received signals are attenuated. To improve the navigation performance in such environments, several enhancement methods can be implemented. For instance, external aid provided through coupling with other sensors has proven to contribute substantially to enhancing navigation performance and robustness. Within this context, coupling a very simple GPS receiver with an Inertial Navigation System (INS) based on low-cost micro-electro-mechanical systems (MEMS) inertial sensors is considered in this paper. In particular, we propose a GPS/INS Tightly Coupled Assisted PLL (TCAPLL) architecture, and present most of the associated challenges that need to be addressed when dealing with very-low-performance MEMS inertial sensors. In addition, we propose a data monitoring system in charge of checking the quality of the measurement flow in the architecture. The implementation of the TCAPLL is discussed in detail, and its performance under different scenarios is assessed. Finally, the architecture is evaluated through a test campaign using a vehicle that is driven in urban environments, with the purpose of highlighting the pros and cons of combining MEMS inertial sensors with GPS over GPS alone. Full article

(This article belongs to the Section Remote Sensors)

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376 KiB

Open AccessArticle

A Disposable Alkaline Phosphatase-Based Biosensor for Vanadium Chronoamperometric Determination

by Ana Lorena Alvarado-Gámez, María Asunción Alonso-Lomillo, Olga Domínguez-Renedo and María Julia Arcos-Martínez

Sensors 2014, 14(2), 3756-3767; https://doi.org/10.3390/s140203756 - 24 Feb 2014

Cited by 10 | Viewed by 7491

Abstract

A chronoamperometric method for vanadium ion determination, based on the inhibition of the enzyme alkaline phosphatase, is reported. Screen-printed carbon electrodes modified with gold nanoparticles were used as transducers for the immobilization of the enzyme. The enzymatic activity over 4-nitrophenyl phosphate sodium salt [...] Read more.

A chronoamperometric method for vanadium ion determination, based on the inhibition of the enzyme alkaline phosphatase, is reported. Screen-printed carbon electrodes modified with gold nanoparticles were used as transducers for the immobilization of the enzyme. The enzymatic activity over 4-nitrophenyl phosphate sodium salt is affected by vanadium ions, which results in a decrease in the chronoamperometric current registered. The developed method has a detection limit of 0.39 ± 0.06 µM, a repeatability of 7.7% (n = 4) and a reproducibility of 8% (n = 3). A study of the possible interferences shows that the presence of Mo(VI), Cr(III), Ca(II) and W(VI), may affect vanadium determination at concentration higher than 1.0 mM. The method was successfully applied to the determination of vanadium in spiked tap water. Full article

(This article belongs to the Special Issue Amperometric Biosensors)

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1257 KiB

Open AccessArticle

DNA-Aptamers Binding Aminoglycoside Antibiotics

by Nadia Nikolaus and Beate Strehlitz

Sensors 2014, 14(2), 3737-3755; https://doi.org/10.3390/s140203737 - 21 Feb 2014

Cited by 51 | Viewed by 10687

Abstract

Aptamers are short, single stranded DNA or RNA oligonucleotides that are able to bind specifically and with high affinity to their non-nucleic acid target molecules. This binding reaction enables their application as biorecognition elements in biosensors and assays. As antibiotic residues pose a [...] Read more.

Aptamers are short, single stranded DNA or RNA oligonucleotides that are able to bind specifically and with high affinity to their non-nucleic acid target molecules. This binding reaction enables their application as biorecognition elements in biosensors and assays. As antibiotic residues pose a problem contributing to the emergence of antibiotic-resistant pathogens and thereby reducing the effectiveness of the drug to fight human infections, we selected aptamers targeted against the aminoglycoside antibiotic kanamycin A with the aim of constructing a robust and functional assay that can be used for water analysis. With this work we show that aptamers that were derived from a Capture-SELEX procedure targeting against kanamycin A also display binding to related aminoglycoside antibiotics. The binding patterns differ among all tested aptamers so that there are highly substance specific aptamers and more group specific aptamers binding to a different variety of aminoglycoside antibiotics. Also the region of the aminoglycoside antibiotics responsible for aptamer binding can be estimated. Affinities of the different aptamers for their target substance, kanamycin A, are measured with different approaches and are in the micromolar range. Finally, the proof of principle of an assay for detection of kanamycin A in a real water sample is given. Full article

(This article belongs to the Special Issue Aptasensors)

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(a) Chemical structures of the selection targets. Numbering of the rings and pKa values of amino groups according to [<a href="#b13-sensors-14-03737" class="html-bibr">13</a>]; (b) Chemical structures of aminoglycoside antibiotics other than kanamycin A. Differences in the structure compared to kanamycin A are marked in yellow. Numbering of the rings and pKa values of amino groups according to [<a href="#b13-sensors-14-03737" class="html-bibr">13</a>]; (c) Chemical structures of amino sugars. Differences in the structure compared to kanamycin A are marked in yellow. Full article ">
(a) Chemical structures of the selection targets. Numbering of the rings and pKa values of amino groups according to [<a href="#b13-sensors-14-03737" class="html-bibr">13</a>]; (b) Chemical structures of aminoglycoside antibiotics other than kanamycin A. Differences in the structure compared to kanamycin A are marked in yellow. Numbering of the rings and pKa values of amino groups according to [<a href="#b13-sensors-14-03737" class="html-bibr">13</a>]; (c) Chemical structures of amino sugars. Differences in the structure compared to kanamycin A are marked in yellow. Full article ">
Secondary structures of selected aptamers and truncations. The 5′and 3′primer binding sites are highlighted in red and green, respectively. The docking sequence is highlighted in blue. Full article ">
Secondary structures of selected aptamers and truncations. The 5′and 3′primer binding sites are highlighted in red and green, respectively. The docking sequence is highlighted in blue. Full article ">
Schematic representation of the bead based assay using fluorescence detection. Fluorescein labeled aptamers: Depicted exemplary is a full length aptamer with 98 nucleobases displaying both primer binding sites. In case of deletions of single nucleobases during selection or in case of the use of truncated versions of the aptamers, the sequences are shorter. Full article ">
Methodology of the affinity tests performed by SPR detection. Aptamers: Depicted exemplary is a full length aptamer with 98 nucleobases displaying both primer binding sites. In case of deletions of single nucleobases during selection or in case of the use of truncated versions of the aptamers, the sequences are shorter. Full article ">
(a) Determination of dissociation constants by fluorescence detection using the bead assay; (b) by fluorescence detection using the MTP assay also showing two negative controls (aptamer truncations # 13_82(19-80) tested with paromomycin that is not bound and # 3_19(1-79), which lost binding properties due to truncation, together with kanamycin A; and (c) by SPR detection using Biacore X 100 (GE Healthcare). Full article ">
(a) Determination of dissociation constants by fluorescence detection using the bead assay; (b) by fluorescence detection using the MTP assay also showing two negative controls (aptamer truncations # 13_82(19-80) tested with paromomycin that is not bound and # 3_19(1-79), which lost binding properties due to truncation, together with kanamycin A; and (c) by SPR detection using Biacore X 100 (GE Healthcare). Full article ">

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Open AccessArticle

Wavelet-Based Watermarking and Compression for ECG Signals with Verification Evaluation

by Kuo-Kun Tseng, Xialong He, Woon-Man Kung, Shuo-Tsung Chen, Minghong Liao and Huang-Nan Huang

Sensors 2014, 14(2), 3721-3736; https://doi.org/10.3390/s140203721 - 21 Feb 2014

Cited by 51 | Viewed by 8885

Abstract

In the current open society and with the growth of human rights, people are more and more concerned about the privacy of their information and other important data. This study makes use of electrocardiography (ECG) data in order to protect individual information. An [...] Read more.

In the current open society and with the growth of human rights, people are more and more concerned about the privacy of their information and other important data. This study makes use of electrocardiography (ECG) data in order to protect individual information. An ECG signal can not only be used to analyze disease, but also to provide crucial biometric information for identification and authentication. In this study, we propose a new idea of integrating electrocardiogram watermarking and compression approach, which has never been researched before. ECG watermarking can ensure the confidentiality and reliability of a user’s data while reducing the amount of data. In the evaluation, we apply the embedding capacity, bit error rate (BER), signal-to-noise ratio (SNR), compression ratio (CR), and compressed-signal to noise ratio (CNR) methods to assess the proposed algorithm. After comprehensive evaluation the final results show that our algorithm is robust and feasible. Full article

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

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Open AccessArticle

An Analysis of the Precision and Reliability of the Leap Motion Sensor and Its Suitability for Static and Dynamic Tracking

by Jože Guna, Grega Jakus, Matevž Pogačnik, Sašo Tomažič and Jaka Sodnik

Sensors 2014, 14(2), 3702-3720; https://doi.org/10.3390/s140203702 - 21 Feb 2014

Cited by 340 | Viewed by 20018

Abstract

We present the results of an evaluation of the performance of the Leap Motion Controller with the aid of a professional, high-precision, fast motion tracking system. A set of static and dynamic measurements was performed with different numbers of tracking objects and configurations. [...] Read more.

We present the results of an evaluation of the performance of the Leap Motion Controller with the aid of a professional, high-precision, fast motion tracking system. A set of static and dynamic measurements was performed with different numbers of tracking objects and configurations. For the static measurements, a plastic arm model simulating a human arm was used. A set of 37 reference locations was selected to cover the controller’s sensory space. For the dynamic measurements, a special V-shaped tool, consisting of two tracking objects maintaining a constant distance between them, was created to simulate two human fingers. In the static scenario, the standard deviation was less than 0.5 mm. The linear correlation revealed a significant increase in the standard deviation when moving away from the controller. The results of the dynamic scenario revealed the inconsistent performance of the controller, with a significant drop in accuracy for samples taken more than 250 mm above the controller’s surface. The Leap Motion Controller undoubtedly represents a revolutionary input device for gesture-based human-computer interaction; however, due to its rather limited sensory space and inconsistent sampling frequency, in its current configuration it cannot currently be used as a professional tracking system. Full article

(This article belongs to the Section Physical Sensors)

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665 KiB

Open AccessArticle

Feature Point Descriptors: Infrared and Visible Spectra

by Pablo Ricaurte, Carmen Chilán, Cristhian A. Aguilera-Carrasco, Boris X. Vintimilla and Angel D. Sappa

Sensors 2014, 14(2), 3690-3701; https://doi.org/10.3390/s140203690 - 21 Feb 2014

Cited by 39 | Viewed by 9367

Abstract

This manuscript evaluates the behavior of classical feature point descriptors when they are used in images from long-wave infrared spectral band and compare them with the results obtained in the visible spectrum. Robustness to changes in rotation, scaling, blur, and additive noise are [...] Read more.

This manuscript evaluates the behavior of classical feature point descriptors when they are used in images from long-wave infrared spectral band and compare them with the results obtained in the visible spectrum. Robustness to changes in rotation, scaling, blur, and additive noise are analyzed using a state of the art framework. Experimental results using a cross-spectral outdoor image data set are presented and conclusions from these experiments are given. Full article

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

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4787 KiB

Open AccessArticle

Description of an Advantageous Optical Label-Free Biosensing Interferometric Read-Out Method to Measure Biological Species

by Miguel Holgado, Francisco J. Sanza, Ana López, Álvaro Lavín, Rafael Casquel and María F. Laguna

Sensors 2014, 14(2), 3675-3689; https://doi.org/10.3390/s140203675 - 21 Feb 2014

Cited by 23 | Viewed by 8039

Abstract

In this article we report a new, simple, and reliable optical read-out detection method able to assess Rotavirus present in human sera as well as in the viral pollution sources. It is based on the interference of two interferometers used as biophotonic transducers. [...] Read more.

In this article we report a new, simple, and reliable optical read-out detection method able to assess Rotavirus present in human sera as well as in the viral pollution sources. It is based on the interference of two interferometers used as biophotonic transducers. The method significantly improves the optical label-free biosensing response measuring both, the concentration of the AgR and its corresponding size. Two different immunoassays were carried out: Bovine Serum Albumin (BSA), and the recognition by its antibody (anti-BSA); and Rotavirus (AgR) and the recognition by its antibody (anti-AgR). In the cases studied, and using as model interferometer a simple Fabry-Perot transducer, we demonstrate a biosensing enhancement of two orders of magnitude in the Limit of Detection (LoD). In fact, this read-out optical method may have significant implications to enhance other optical label-free photonic transducers reported in the scientific literature. Full article

(This article belongs to the Special Issue Photonic Sensors for Industrial, Environmental and Health Monitoring)

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(A) Description of the Interferometric Optical Detection Method (IODM) particularized for a Fabry-Perot interferometer based on a SiO2 thin layer over Si as transducer model, (B) Optical simulation of the transduction function fTRANS coming from the reflectance optical response of IFOut for different biofilms thicknesses, (C) Theoretical sensing response considering the peak-to peak signal amplitude of fTRANS as transducing signal. It is also shown the different size of expected biomolecules to be detected. Full article ">
(A) Interferometric Optical Detection Method (IODM) considering IOut and IRef of fTRANS as their corresponding Optical Power (POut, PRef) for a given wavenumber range [wna, wnb] highlighted in blue. (B) Description of IODM particularized for a given wavenumber. (C) Theoretical response of the Increased Relative Optical Power (IROP) as a function of the biofilm thickness and (D) a detail of the IROP for molecules of small molecular mass. Full article ">
(A) Optical image of a chip with 36 FPIs. (B) A schematic representation of the Biosensing process for the IODM, where a reference interferometer IFRef and a signal Interferometers IFOut are used. Full article ">
Experimental response for measuring BSA / Anti-BSA immunoassay: (A) fTRANS response where in brown is represented the experimental signal and in black the theoretical fitting of the model. (B) Biosensing response starting with the immobilization of BSA and the increasing concentrations of anti-BSA. Full article ">
Experimental response for measuring Rotavirus/anti-Rotavirus immunoassay: (A) Experimental fTRANS obtained and (B) the detailed response within 13,192–11,890 cm−1. (C) Biosensing response for anti-AgR recognition. (D) Schematic representation of the experiment carried out and (E) theoretical biofilm thickness calculation. Full article ">

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Open AccessArticle

Sparse Representations-Based Super-Resolution of Key-Frames Extracted from Frames-Sequences Generated by a Visual Sensor Network

by Muhammad Sajjad, Irfan Mehmood and Sung Wook Baik

Sensors 2014, 14(2), 3652-3674; https://doi.org/10.3390/s140203652 - 21 Feb 2014

Cited by 23 | Viewed by 6576

Abstract

Visual sensor networks (VSNs) usually generate a low-resolution (LR) frame-sequence due to energy and processing constraints. These LR-frames are not very appropriate for use in certain surveillance applications. It is very important to enhance the resolution of the captured LR-frames using resolution enhancement [...] Read more.

Visual sensor networks (VSNs) usually generate a low-resolution (LR) frame-sequence due to energy and processing constraints. These LR-frames are not very appropriate for use in certain surveillance applications. It is very important to enhance the resolution of the captured LR-frames using resolution enhancement schemes. In this paper, an effective framework for a super-resolution (SR) scheme is proposed that enhances the resolution of LR key-frames extracted from frame-sequences captured by visual-sensors. In a VSN, a visual processing hub (VPH) collects a huge amount of visual data from camera sensors. In the proposed framework, at the VPH, key-frames are extracted using our recent key-frame extraction technique and are streamed to the base station (BS) after compression. A novel effective SR scheme is applied at BS to produce a high-resolution (HR) output from the received key-frames. The proposed SR scheme uses optimized orthogonal matching pursuit (OOMP) for sparse-representation recovery in SR. OOMP does better in terms of detecting true sparsity than orthogonal matching pursuit (OMP). This property of the OOMP helps produce a HR image which is closer to the original image. The K-SVD dictionary learning procedure is incorporated for dictionary learning. Batch-OMP improves the dictionary learning process by removing the limitation in handling a large set of observed signals. Experimental results validate the effectiveness of the proposed scheme and show its superiority over other state-of-the-art schemes. Full article

(This article belongs to the Section Sensor Networks)

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Open AccessArticle

Driving-Simulator-Based Test on the Effectiveness of Auditory Red-Light Running Vehicle Warning System Based on Time-To-Collision Sensor

by Xuedong Yan, Qingwan Xue, Lu Ma and Yongcun Xu

Sensors 2014, 14(2), 3631-3651; https://doi.org/10.3390/s140203631 - 21 Feb 2014

Cited by 38 | Viewed by 7598

Abstract

The collision avoidance warning system is an emerging technology designed to assist drivers in avoiding red-light running (RLR) collisions at intersections. The aim of this paper is to evaluate the effect of auditory warning information on collision avoidance behaviors in the RLR pre-crash [...] Read more.

The collision avoidance warning system is an emerging technology designed to assist drivers in avoiding red-light running (RLR) collisions at intersections. The aim of this paper is to evaluate the effect of auditory warning information on collision avoidance behaviors in the RLR pre-crash scenarios and further to examine the casual relationships among the relevant factors. A driving-simulator-based experiment was designed and conducted with 50 participants. The data from the experiments were analyzed by approaches of ANOVA and structural equation modeling (SEM). The collisions avoidance related variables were measured in terms of brake reaction time (BRT), maximum deceleration and lane deviation in this study. It was found that the collision avoidance warning system can result in smaller collision rates compared to the without-warning condition and lead to shorter reaction times, larger maximum deceleration and less lane deviation. Furthermore, the SEM analysis illustrate that the audio warning information in fact has both direct and indirect effect on occurrence of collisions, and the indirect effect plays a more important role on collision avoidance than the direct effect. Essentially, the auditory warning information can assist drivers in detecting the RLR vehicles in a timely manner, thus providing drivers more adequate time and space to decelerate to avoid collisions with the conflicting vehicles. Full article

(This article belongs to the Section Physical Sensors)

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Open AccessReview

Conducting Polymer-Based Nanohybrid Transducers: A Potential Route to High Sensitivity and Selectivity Sensors

by Seon Joo Park, Oh Seok Kwon, Ji Eun Lee, Jyongsik Jang and Hyeonseok Yoon

Sensors 2014, 14(2), 3604-3630; https://doi.org/10.3390/s140203604 - 20 Feb 2014

Cited by 83 | Viewed by 14136

Abstract

The development of novel sensing materials provides good opportunities to realize previously unachievable sensor performance. In this review, conducting polymer-based nanohybrids are highlighted as innovative transducers for high-performance chemical and biological sensing devices. Synthetic strategies of the nanohybrids are categorized into four groups: [...] Read more.

The development of novel sensing materials provides good opportunities to realize previously unachievable sensor performance. In this review, conducting polymer-based nanohybrids are highlighted as innovative transducers for high-performance chemical and biological sensing devices. Synthetic strategies of the nanohybrids are categorized into four groups: (1) impregnation, followed by reduction; (2) concurrent redox reactions; (3) electrochemical deposition; (4) seeding approach. Nanocale hybridization of conducting polymers with inorganic components can lead to improved sorption, catalytic reaction and/or transport behavior of the material systems. The nanohybrids have thus been used to detect nerve agents, toxic gases, volatile organic compounds, glucose, dopamine, and DNA. Given further advances in nanohybrids synthesis, it is expected that sensor technology will also evolve, especially in terms of sensitivity and selectivity. Full article

(This article belongs to the Special Issue Inorganic-Organic Hybrid Biological and Chemical Sensors)

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Schematic illustration of reaction steps for the covalent immobilization of fluorescent dye molecules on the surface of carboxylated PPy (CPPy) nanotubes: the first step involves the coupling reaction of CPPy nanotubes with ethylenediamine as a diamino linker, and then pyreneacetic acid molecules are covalently bonded to the nanotube surface by a condensation reaction between the carboxylic groups and the surface amino groups. The fluorescent dye molecules were tracked in the samples using confocal laser scanning electron microscopy (CLSM) (λexc = 458 nm): CSLM images of the nanotubes synthesized with the P3CA-to-pyrrole molar ratios of (a) 1:15 and (b) 1:30. With permission from [<a href="#b19-sensors-14-03604" class="html-bibr">19</a>]; Copyright 2008, Wiley-VCH Verlag GmbH & Co. KGaA. Full article ">
Schematic illustration of the fabrication of Pd nanoparticles-decorated MCPPy nanotubes. With permission from [<a href="#b22-sensors-14-03604" class="html-bibr">22</a>]; Copyright 2006, Wiley-VCH Verlag GmbH & Co. KGaA. Full article ">
TEM images of (a) a MCPPy nanotube and (b) a Pd nanoparticles-decorated MCPPy nanotube prepared with a dilute PdCl2 solution. The inset images are the electron diffraction patterns; (c) and (d) magnified TEM images of Pd nanoparticles-decorated MCPPy nanotubes obtained with the palladium salt concentrations of 10−4 and 10−3 M, respectively. The Pd nanoparticle size is illustrated in the inset histogram. With permission from [<a href="#b22-sensors-14-03604" class="html-bibr">22</a>]; Copyright 2006, Wiley-VCH Verlag GmbH & Co. KGaA. Full article ">
Schematic illustration of the formation mechanism of silver-PPy nanoparticles: (a) the scheme describing the chemical reaction between pyrrole and silver cation; (b) the reaction process could be divided into three stages (I, II, and III). Adapted with permission from [<a href="#b30-sensors-14-03604" class="html-bibr">30</a>]; Copyright 2012, American Chemical Society. Full article ">
SEM images of CdS-PPy heterojunction nanowires: (a) side view image of CdS-PPy nanowires inside the alumina membrane template; (b) typical image of a single CdS-PPy nanowire; (c) element mapping of a single CdS-PPy nanowire; (d) optical image of a single CdS-PPy nanowire; (e) fluorescent image of a single CdS-PPy nanowire excited by a 405 nm laser. Adapted with permission from [<a href="#b33-sensors-14-03604" class="html-bibr">33</a>]; Copyright 2008, American Chemical Society. Full article ">
SEM images of PANI nanofibers synthesized with nanofiber seeds (insets): (a) single-walled carbon nanotubes; (b) V2O5 nanofibers. Adapted with permission from [<a href="#b39-sensors-14-03604" class="html-bibr">39</a>]; Copyright 2012, American Chemical Society. Full article ">
Responses of DMMP gas sensor toward (a) methanol and (b) DMMP. Adapted with permission from [<a href="#b45-sensors-14-03604" class="html-bibr">45</a>]; Copyright 2010, Elsevier B.V. Full article ">
(a) XRD pattern of PPy/WO3 nanohybrids and (b) their response-recovery curves to H2S at 90 °C. Adapted with permission from <a href="#b49-sensors-14-03604" class="html-bibr">Ref. [49]</a>; Copyright 2006, Elsevier B.V. (c) XRD pattern (the three peaks correspond to γ-Fe2O3 phase) of PPy/γ-Fe2O3 nanohybrids annealed at 150 °C and (d) their response curve (voltage vs. time) to 0.1% H2S at 90 °C. Adapted with permission from [<a href="#b50-sensors-14-03604" class="html-bibr">50</a>]; Copyright 2006, Elsevier B.V. Full article ">
(a) TEM image of PTP (20%)/SnO2 composites; (b) The stability of PTP/SnO2 sensor to 100 ppm NOx. Adapted with permission from [<a href="#b54-sensors-14-03604" class="html-bibr">54</a>]; Copyright 2012, American Chemical Society. Full article ">

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Open AccessArticle

Investigating Energy-Saving Potentials in the Cloud

by Da-Sheng Lee

Sensors 2014, 14(2), 3578-3603; https://doi.org/10.3390/s140203578 - 20 Feb 2014

Cited by 2 | Viewed by 6136

Abstract

Collecting webpage messages can serve as a sensor for investigating the energy-saving potential of buildings. Focusing on stores, a cloud sensor system is developed to collect data and determine their energy-saving potential. The owner of a store under investigation must register online, report [...] Read more.

Collecting webpage messages can serve as a sensor for investigating the energy-saving potential of buildings. Focusing on stores, a cloud sensor system is developed to collect data and determine their energy-saving potential. The owner of a store under investigation must register online, report the store address, area, and the customer ID number on the electric meter. The cloud sensor system automatically surveys the energy usage records by connecting to the power company website and calculating the energy use index (EUI) of the store. Other data includes the chain store check, company capital, location price, and the influence of weather conditions on the store; even the exposure frequency of store under investigation may impact the energy usage collected online. After collecting data from numerous stores, a multi-dimensional data array is constructed to determine energy-saving potential by identifying stores with similarity conditions. Similarity conditions refer to analyzed results that indicate that two stores have similar capital, business scale, weather conditions, and exposure frequency on web. Calculating the EUI difference or pure technical efficiency of stores, the energy-saving potential is determined. In this study, a real case study is performed. An 8-dimensional (8D) data array is constructed by surveying web data related to 67 stores. Then, this study investigated the savings potential of the 33 stores, using a site visit, and employed the cloud sensor system to determine the saving potential. The case study results show good agreement between the data obtained by the site visit and the cloud investigation, with errors within 4.17%. Among 33 the samples, eight stores have low saving potentials of less than 5%. The developed sensor on the cloud successfully identifies them as having low saving potential and avoids wasting money on the site visit. Full article

(This article belongs to the Section Sensor Networks)

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780 KiB

Open AccessArticle

A Proposed Scalable Design and Simulation of Wireless Sensor Network-Based Long-Distance Water Pipeline Leakage Monitoring System

by Abdulaziz S. Almazyad, Yasser M. Seddiq, Ahmed M. Alotaibi, Ahmed Y. Al-Nasheri, Mohammed S. BenSaleh, Abdulfattah M. Obeid and Syed Manzoor Qasim

Sensors 2014, 14(2), 3557-3577; https://doi.org/10.3390/s140203557 - 20 Feb 2014

Cited by 71 | Viewed by 10851

Abstract

Anomalies such as leakage and bursts in water pipelines have severe consequences for the environment and the economy. To ensure the reliability of water pipelines, they must be monitored effectively. Wireless Sensor Networks (WSNs) have emerged as an effective technology for monitoring critical [...] Read more.

Anomalies such as leakage and bursts in water pipelines have severe consequences for the environment and the economy. To ensure the reliability of water pipelines, they must be monitored effectively. Wireless Sensor Networks (WSNs) have emerged as an effective technology for monitoring critical infrastructure such as water, oil and gas pipelines. In this paper, we present a scalable design and simulation of a water pipeline leakage monitoring system using Radio Frequency IDentification (RFID) and WSN technology. The proposed design targets long-distance aboveground water pipelines that have special considerations for maintenance, energy consumption and cost. The design is based on deploying a group of mobile wireless sensor nodes inside the pipeline and allowing them to work cooperatively according to a prescheduled order. Under this mechanism, only one node is active at a time, while the other nodes are sleeping. The node whose turn is next wakes up according to one of three wakeup techniques: location-based, time-based and interrupt-driven. In this paper, mathematical models are derived for each technique to estimate the corresponding energy consumption and memory size requirements. The proposed equations are analyzed and the results are validated using simulation. Full article

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

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711 KiB

Open AccessArticle

Laccase Biosensor Based on Electrospun Copper/Carbon Composite Nanofibers for Catechol Detection

by Jiapeng Fu, Hui Qiao, Dawei Li, Lei Luo, Ke Chen and Qufu Wei

Sensors 2014, 14(2), 3543-3556; https://doi.org/10.3390/s140203543 - 20 Feb 2014

Cited by 67 | Viewed by 10018

Abstract

The study compared the biosensing properties of laccase biosensors based on carbon nanofibers (CNFs) and copper/carbon composite nanofibers (Cu/CNFs). The two kinds of nanofibers were prepared by electrospinning and carbonization under the same conditions. Scanning electron microscopy (SEM), X-ray diffraction (XRD) and Raman [...] Read more.

The study compared the biosensing properties of laccase biosensors based on carbon nanofibers (CNFs) and copper/carbon composite nanofibers (Cu/CNFs). The two kinds of nanofibers were prepared by electrospinning and carbonization under the same conditions. Scanning electron microscopy (SEM), X-ray diffraction (XRD) and Raman spectroscopy were employed to investigate the morphologies and structures of CNFs and Cu/CNFs. The amperometric results indicated that the Cu/CNFs/laccase(Lac)/Nafion/glass carbon electrode (GCE) possessed reliable analytical performance for the detection of catechol. The sensitivity of the Cu/CNFs/Lac/Nafion/GCE reached 33.1 μA/mM, larger than that of CNFs/Lac/Nafion/GCE. Meanwhile, Cu/CNFs/Lac/Nafion/GCE had a wider linear range from 9.95 × 10⁻⁶ to 9.76 × 10⁻³ M and a lower detection limit of 1.18 μM than CNFs/Lac/Nafion/GCE. Moreover, it exhibited a good repeatability, reproducibility, selectivity and long-term stability, revealing that electrospun Cu/CNFs have great potential in biosensing. Full article

(This article belongs to the Special Issue Amperometric Biosensors)

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207 KiB

Open AccessArticle

Characterizing and Authenticating Montilla-Moriles PDO Vinegars Using Near Infrared Reflectance Spectroscopy (NIRS) Technology

by María-José De la Haba, Mar Arias, Pilar Ramírez, María-Isabel López and María-Teresa Sánchez

Sensors 2014, 14(2), 3528-3542; https://doi.org/10.3390/s140203528 - 20 Feb 2014

Cited by 20 | Viewed by 7315

Abstract

This study assessed the potential of near infrared (NIR) spectroscopy as a non-destructive method for characterizing Protected Designation of Origin (PDO) “Vinagres de Montilla-Moriles” wine vinegars and for classifying them as a function of the manufacturing process used. Three spectrophotometers were evaluated for [...] Read more.

This study assessed the potential of near infrared (NIR) spectroscopy as a non-destructive method for characterizing Protected Designation of Origin (PDO) “Vinagres de Montilla-Moriles” wine vinegars and for classifying them as a function of the manufacturing process used. Three spectrophotometers were evaluated for this purpose: two monochromator instruments (Foss NIRSystems 6500 SY-I and Foss NIRSystems 6500 SY-II; spectral range 400–2,500 nm in both cases) and a diode-array instrument (Corona 45 VIS/NIR; spectral range 380–1,700 nm). A total of 70 samples were used to predict major chemical quality parameters (total acidity, fixed acidity, volatile acidity, pH, dry extract, ash, acetoin, methanol, total polyphenols, color (tonality and intensity), and alcohol content), and to construct models for the classification of vinegars as a function of the manufacturing method used. The results obtained indicate that this non-invasive technology can be used successfully by the vinegar industry and by PDO regulators for the routine analysis of vinegars in order to authenticate them and to detect potential fraud. Slightly better results were achieved with the two monochromator instruments. The findings also highlight the potential of these NIR instruments for predicting the manufacturing process used, this being of particular value for the industrial authentication of traditional wine vinegars. Full article

(This article belongs to the Section Physical Sensors)

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352 KiB

Open AccessReview

A Survey on Sensor Coverage and Visual Data Capturing/Processing/Transmission in Wireless Visual Sensor Networks

by Florence G. H. Yap and Hong-Hsu Yen

Sensors 2014, 14(2), 3506-3527; https://doi.org/10.3390/s140203506 - 20 Feb 2014

Cited by 59 | Viewed by 8880

Abstract

Wireless Visual Sensor Networks (WVSNs) where camera-equipped sensor nodes can capture, process and transmit image/video information have become an important new research area. As compared to the traditional wireless sensor networks (WSNs) that can only transmit scalar information (e.g., temperature), the visual data [...] Read more.

Wireless Visual Sensor Networks (WVSNs) where camera-equipped sensor nodes can capture, process and transmit image/video information have become an important new research area. As compared to the traditional wireless sensor networks (WSNs) that can only transmit scalar information (e.g., temperature), the visual data in WVSNs enable much wider applications, such as visual security surveillance and visual wildlife monitoring. However, as compared to the scalar data in WSNs, visual data is much bigger and more complicated so intelligent schemes are required to capture/process/ transmit visual data in limited resources (hardware capability and bandwidth) WVSNs. WVSNs introduce new multi-disciplinary research opportunities of topics that include visual sensor hardware, image and multimedia capture and processing, wireless communication and networking. In this paper, we survey existing research efforts on the visual sensor hardware, visual sensor coverage/deployment, and visual data capture/ processing/transmission issues in WVSNs. We conclude that WVSN research is still in an early age and there are still many open issues that have not been fully addressed. More new novel multi-disciplinary, cross-layered, distributed and collaborative solutions should be devised to tackle these challenging issues in WVSNs. Full article

(This article belongs to the Section Sensor Networks)

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595 KiB

Open AccessArticle

RF-to-DC Characteristics of Direct Irradiated On-Chip Gallium Arsenide Schottky Diode and Antenna for Application in Proximity Communication System

by Farahiyah Mustafa and Abdul Manaf Hashim

Sensors 2014, 14(2), 3493-3505; https://doi.org/10.3390/s140203493 - 20 Feb 2014

Viewed by 7524

Abstract

We report the RF-to-DC characteristics of the integrated AlGaAs/GaAs Schottky diode and antenna under the direct injection and irradiation condition. The conversion efficiency up to 80% under direct injection of 1 GHz signal to the diode was achieved. It was found that the [...] Read more.

We report the RF-to-DC characteristics of the integrated AlGaAs/GaAs Schottky diode and antenna under the direct injection and irradiation condition. The conversion efficiency up to 80% under direct injection of 1 GHz signal to the diode was achieved. It was found that the reduction of series resistance and parallel connection of diode and load tend to lead to the improvement of RF-to-DC conversion efficiency. Under direct irradiation from antenna-to-antenna method, the output voltage of 35 mV was still obtainable for the distance of 8 cm between both antennas in spite of large mismatch in the resonant frequency between the diode and the connected antenna. Higher output voltage in volt range is expected to be achievable for the well-matching condition. The proposed on-chip AlGaAs/GaAs HEMT Schottky diode and antenna seems to be a promising candidate to be used for application in proximity communication system as a wireless low power source as well as a highly sensitive RF detector. Full article

(This article belongs to the Section Physical Sensors)

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673 KiB

Open AccessArticle

Modeling of the Through-the-Thickness Electric Potentials of a Piezoelectric Bimorph Using the Spectral Element Method

by Xingjian Dong, Zhike Peng, Hongxing Hua and Guang Meng

Sensors 2014, 14(2), 3477-3492; https://doi.org/10.3390/s140203477 - 20 Feb 2014

Cited by 6 | Viewed by 5709

Abstract

An efficient spectral element (SE) with electric potential degrees of freedom (DOF) is proposed to investigate the static electromechanical responses of a piezoelectric bimorph for its actuator and sensor functions. A sublayer model based on the piecewise linear approximation for the electric potential [...] Read more.

An efficient spectral element (SE) with electric potential degrees of freedom (DOF) is proposed to investigate the static electromechanical responses of a piezoelectric bimorph for its actuator and sensor functions. A sublayer model based on the piecewise linear approximation for the electric potential is used to describe the nonlinear distribution of electric potential through the thickness of the piezoelectric layers. An equivalent single layer (ESL) model based on first-order shear deformation theory (FSDT) is used to describe the displacement field. The Legendre orthogonal polynomials of order 5 are used in the element interpolation functions. The validity and the capability of the present SE model for investigation of global and local responses of the piezoelectric bimorph are confirmed by comparing the present solutions with those obtained from coupled 3-D finite element (FE) analysis. It is shown that, without introducing any higher-order electric potential assumptions, the current method can accurately describe the distribution of the electric potential across the thickness even for a rather thick bimorph. It is revealed that the effect of electric potential is significant when the bimorph is used as sensor while the effect is insignificant when the bimorph is used as actuator, and therefore, the present study may provide a better understanding of the nonlinear induced electric potential for bimorph sensor and actuator. Full article

(This article belongs to the Section Physical Sensors)

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719 KiB

Open AccessArticle

A New Omni-Directional EMAT for Ultrasonic Lamb Wave Tomography Imaging of Metallic Plate Defects

by Songling Huang, Zheng Wei, Wei Zhao and Shen Wang

Sensors 2014, 14(2), 3458-3476; https://doi.org/10.3390/s140203458 - 20 Feb 2014

Cited by 71 | Viewed by 8703

Abstract

This paper proposes a new omni-directional electromagnetic acoustic transducer (EMAT) for the ultrasonic Lamb wave (ULW) tomography imaging (TI) of defects in metallic plates. The proposed EMAT is composed of a permanent magnet and a coil with a contra-flexure structure. This new EMAT [...] Read more.

This paper proposes a new omni-directional electromagnetic acoustic transducer (EMAT) for the ultrasonic Lamb wave (ULW) tomography imaging (TI) of defects in metallic plates. The proposed EMAT is composed of a permanent magnet and a coil with a contra-flexure structure. This new EMAT coil structure is used for omni-directional ULW transmission and reception and ULW TI for the first time. The theoretical background and the working principles of this EMAT are presented and analyzed. The experimental results of its use on a 3 mm thick aluminum plate indicate that the EMAT with a contra-flexure coil (CFC) can transmit and receive a pure single A0 mode ULW with a high signal-to-noise ratio (SNR). Thus, the extraction of the projection data used for ULW TI may be performed accurately. The circumferential consistency of the projection data is only slightly influenced by the distortion of the eddy current field that is induced by the new CFC with an irregular shape. When the new EMAT array is used for ULW TI using the cross-hole method and SIRT arithmetic, a desirable imaging quality can be achieved, and the estimated size of an artificial corrosion defect agreed well with its actual value. The relation between the reconstruction resolution and the number of the new EMATs used is analyzed. More TI experiments are carried out when the aluminum plate defect is in two different locations relative to the EMAT array, for the further investigation of the performances of the new EMATs. Full article

(This article belongs to the Section Physical Sensors)

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The sectional model of the free aluminum plate in space. Full article ">
The ULW frequency dispersion curves of (a) cp and (b) cg for the 3 mm thick aluminum plate. Full article ">
The structure and schematic diagrams of the omni-directional EMATs: (a) the structure of the new EMAT; (b) the traditional CWSC; and (c) the new CFC. Full article ">
The schematic diagrams of experimental system. (a) The experimental system; and (b) the tone burst pulse excitation signal. Full article ">
Schematic diagram of the EMAT positions and the propagation paths of the ULW pulses. Full article ">
Detected waveforms of the A0 mode ULW transmitting and receiving experiments. (a) Using the new CFC EMATs, the receiver at position 1; (b) Using the new CFC EMATs, the receiver at position 2; (c) Using the new CFC EMATs, the receiver at position 3; (d) Using the traditional CWSC EMATs, the receiver at position 1; (e) Using the traditional CWSC EMATs, the receiver at position 2; (f) Using the traditional CWSC EMATs, the receiver at position 3. Full article ">
Schematic diagram of the EMATs positions and directions. Full article ">
Detected waveforms when the receiver direction remains at 90° and the transmitter direction changes. (a) Transmitter direction is 30°; (b) Transmitter direction is 60°; (c) Transmitter direction is 90°; (d) Transmitter direction is 180°. Full article ">
Results of the circumferential consistency verification experiments: (a) V of the different transmitter directions; (b) t of the different transmitter directions; (c) V of the different receiver directions; and (d) t of the different receiver directions. Full article ">

759 KiB

Open AccessArticle

Characterization of Scintillating X-ray Optical Fiber Sensors

by Dan Sporea, Laura Mihai, Ion Vâţă, Denis McCarthy, Sinead O'Keeffe and Elfed Lewis

Sensors 2014, 14(2), 3445-3457; https://doi.org/10.3390/s140203445 - 19 Feb 2014

Cited by 12 | Viewed by 7551

Abstract

The paper presents a set of tests carried out in order to evaluate the design characteristics and the operating performance of a set of six X-ray extrinsic optical fiber sensors. The extrinsic sensor we developed is intended to be used as a low [...] Read more.

The paper presents a set of tests carried out in order to evaluate the design characteristics and the operating performance of a set of six X-ray extrinsic optical fiber sensors. The extrinsic sensor we developed is intended to be used as a low energy X-ray detector for monitoring radiation levels in radiotherapy, industrial applications and for personnel dosimetry. The reproducibility of the manufacturing process and the characteristics of the sensors were assessed. The sensors dynamic range, linearity, sensitivity, and reproducibility are evaluated through radioluminescence measurements, X-ray fluorescence and X-ray imaging investigations. Their response to the operating conditions of the excitation source was estimated. The effect of the sensors design and implementation, on the collecting efficiency of the radioluminescence signal was measured. The study indicated that the sensors are efficient only in the first 5 mm of the tip, and that a reflective coating can improve their response. Additional tests were done to investigate the concentricity of the sensors tip against the core of the optical fiber guiding the optical signal. The influence of the active material concentration on the sensor response to X-ray was studied. The tests were carried out by measuring the radioluminescence signal with an optical fiber spectrometer and with a Multi-Pixel Photon Counter. Full article

(This article belongs to the Special Issue Photonic Sensors for Industrial, Environmental and Health Monitoring)

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Graphical abstract

663 KiB

Open AccessArticle

Double Fault Detection of Cone-Shaped Redundant IMUs Using Wavelet Transformation and EPSA

by Wonhee Lee and Chan Gook Park

Sensors 2014, 14(2), 3428-3444; https://doi.org/10.3390/s140203428 - 19 Feb 2014

Cited by 24 | Viewed by 6087

Abstract

A model-free hybrid fault diagnosis technique is proposed to improve the performance of single and double fault detection and isolation. This is a model-free hybrid method which combines the extended parity space approach (EPSA) with a multi-resolution signal decomposition by using a discrete [...] Read more.

A model-free hybrid fault diagnosis technique is proposed to improve the performance of single and double fault detection and isolation. This is a model-free hybrid method which combines the extended parity space approach (EPSA) with a multi-resolution signal decomposition by using a discrete wavelet transform (DWT). Conventional EPSA can detect and isolate single and double faults. The performance of fault detection and isolation is influenced by the relative size of noise and fault. In this paper; the DWT helps to cancel the high frequency sensor noise. The proposed technique can improve low fault detection and isolation probability by utilizing the EPSA with DWT. To verify the effectiveness of the proposed fault detection method Monte Carlo numerical simulations are performed for a redundant inertial measurement unit (RIMU). Full article

(This article belongs to the Section Physical Sensors)

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1218 KiB

Open AccessArticle

Inductive Sensor Performance in Partial Discharges and Noise Separation by Means of Spectral Power Ratios

by Jorge Alfredo Ardila-Rey, Mónica Victoria Rojas-Moreno, Juan Manuel Martínez-Tarifa and Guillermo Robles

Sensors 2014, 14(2), 3408-3427; https://doi.org/10.3390/s140203408 - 19 Feb 2014

Cited by 30 | Viewed by 9373

Abstract

Partial discharge (PD) detection is a standardized technique to qualify electrical insulation in machines and power cables. Several techniques that analyze the waveform of the pulses have been proposed to discriminate noise from PD activity. Among them, spectral power ratio representation shows great [...] Read more.

Partial discharge (PD) detection is a standardized technique to qualify electrical insulation in machines and power cables. Several techniques that analyze the waveform of the pulses have been proposed to discriminate noise from PD activity. Among them, spectral power ratio representation shows great flexibility in the separation of the sources of PD. Mapping spectral power ratios in two-dimensional plots leads to clusters of points which group pulses with similar characteristics. The position in the map depends on the nature of the partial discharge, the setup and the frequency response of the sensors. If these clusters are clearly separated, the subsequent task of identifying the source of the discharge is straightforward so the distance between clusters can be a figure of merit to suggest the best option for PD recognition. In this paper, two inductive sensors with different frequency responses to pulsed signals, a high frequency current transformer and an inductive loop sensor, are analyzed to test their performance in detecting and separating the sources of partial discharges. Full article

(This article belongs to the Special Issue State-of-the-Art Sensors Technology in Spain 2013)

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879 KiB

Open AccessArticle

Corrosion in Reinforced Concrete Panels: Wireless Monitoring and Wavelet-Based Analysis

by Guofu Qiao, Guodong Sun, Yi Hong, Tiejun Liu and Xinchun Guan

Sensors 2014, 14(2), 3395-3407; https://doi.org/10.3390/s140203395 - 19 Feb 2014

Cited by 11 | Viewed by 6748

Abstract

To realize the efficient data capture and accurate analysis of pitting corrosion of the reinforced concrete (RC) structures, we first design and implement a wireless sensor and network (WSN) to monitor the pitting corrosion of RC panels, and then, we propose a wavelet-based [...] Read more.

To realize the efficient data capture and accurate analysis of pitting corrosion of the reinforced concrete (RC) structures, we first design and implement a wireless sensor and network (WSN) to monitor the pitting corrosion of RC panels, and then, we propose a wavelet-based algorithm to analyze the corrosion state with the corrosion data collected by the wireless platform. We design a novel pitting corrosion-detecting mote and a communication protocol such that the monitoring platform can sample the electrochemical emission signals of corrosion process with a configured period, and send these signals to a central computer for the analysis. The proposed algorithm, based on the wavelet domain analysis, returns the energy distribution of the electrochemical emission data, from which close observation and understanding can be further achieved. We also conducted test-bed experiments based on RC panels. The results verify the feasibility and efficiency of the proposed WSN system and algorithms. Full article

(This article belongs to the Section Sensor Networks)

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The architecture of the wireless corrosion monitoring system. Full article ">
Schematic of the connecting circuit for the wireless corrosion sensor. Full article ">
Routing algorithm for the wireless corrosion monitoring network. Full article ">
Schematic of the fast wavelet transform algorithm. Full article ">
The schematic plan of the wireless corrosion monitoring system for RC panels. Full article ">
Electrochemical emission data of the passive state reinforced concrete panel. (a) and (b) are the electrochemical potential emission and the electrochemical current emission of the wireless mote SN0, respectively. Full article ">
The electrochemical emission data of the active state RC panel. (a1), (a2), (a3) and (b1), (b2), (b3) are the electrochemical potential emission and electrochemical current emission of the wireless motes SN1, SN2 and SN3 located along the diagonal line of the RC panel in <a href="#f6-sensors-14-03395" class="html-fig">Figure 6</a>, respectively. Full article ">
Energy distribution plots of the electrochemical emission signals in wavelet domain. (a) and (b) are the energy distribution plots of the electrochemical potential emission and electrochemical current emission, respectively. Full article ">

934 KiB

Open AccessReview

Gait Analysis Methods: An Overview of Wearable and Non-Wearable Systems, Highlighting Clinical Applications

by Alvaro Muro-de-la-Herran, Begonya Garcia-Zapirain and Amaia Mendez-Zorrilla

Sensors 2014, 14(2), 3362-3394; https://doi.org/10.3390/s140203362 - 19 Feb 2014

Cited by 854 | Viewed by 51887

Abstract

This article presents a review of the methods used in recognition and analysis of the human gait from three different approaches: image processing, floor sensors and sensors placed on the body. Progress in new technologies has led the development of a series of [...] Read more.

This article presents a review of the methods used in recognition and analysis of the human gait from three different approaches: image processing, floor sensors and sensors placed on the body. Progress in new technologies has led the development of a series of devices and techniques which allow for objective evaluation, making measurements more efficient and effective and providing specialists with reliable information. Firstly, an introduction of the key gait parameters and semi-subjective methods is presented. Secondly, technologies and studies on the different objective methods are reviewed. Finally, based on the latest research, the characteristics of each method are discussed. 40% of the reviewed articles published in late 2012 and 2013 were related to non-wearable systems, 37.5% presented inertial sensor-based systems, and the remaining 22.5% corresponded to other wearable systems. An increasing number of research works demonstrate that various parameters such as precision, conformability, usability or transportability have indicated that the portable systems based on body sensors are promising methods for gait analysis. Full article

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

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Graphical abstract

916 KiB

Open AccessArticle

Feature Optimization for Long-Range Visual Homing in Changing Environments

by Qidan Zhu, Xue Liu and Chengtao Cai

Sensors 2014, 14(2), 3342-3361; https://doi.org/10.3390/s140203342 - 19 Feb 2014

Cited by 10 | Viewed by 5664

Abstract

This paper introduces a feature optimization method for robot long-range feature-based visual homing in changing environments. To cope with the changing environmental appearance, the optimization procedure is introduced to distinguish the most relevant features for feature-based visual homing, including the spatial distribution, selection [...] Read more.

This paper introduces a feature optimization method for robot long-range feature-based visual homing in changing environments. To cope with the changing environmental appearance, the optimization procedure is introduced to distinguish the most relevant features for feature-based visual homing, including the spatial distribution, selection and updating. In the previous research on feature-based visual homing, less effort has been spent on the way to improve the feature distribution to get uniformly distributed features, which are closely related to homing performance. This paper presents a modified feature extraction algorithm to decrease the influence of anisotropic feature distribution. In addition, the feature selection and updating mechanisms, which have hardly drawn any attention in the domain of feature-based visual homing, are crucial in improving homing accuracy and in maintaining the representation of changing environments. To verify the feasibility of the proposal, several comprehensive evaluations are conducted. The results indicate that the feature optimization method can find optimal feature sets for feature-based visual homing, and adapt the appearance representation to the changing environments as well. Full article

(This article belongs to the Section Physical Sensors)

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Graphical abstract

795 KiB

Open AccessArticle

A Vibration-Based MEMS Piezoelectric Energy Harvester and Power Conditioning Circuit

by Hua Yu, Jielin Zhou, Licheng Deng and Zhiyu Wen

Sensors 2014, 14(2), 3323-3341; https://doi.org/10.3390/s140203323 - 19 Feb 2014

Cited by 175 | Viewed by 17700

Abstract

This paper presents a micro-electro-mechanical system (MEMS) piezoelectric power generator array for vibration energy harvesting. A complete design flow of the vibration-based energy harvester using the finite element method (FEM) is proposed. The modal analysis is selected to calculate the resonant frequency of [...] Read more.

This paper presents a micro-electro-mechanical system (MEMS) piezoelectric power generator array for vibration energy harvesting. A complete design flow of the vibration-based energy harvester using the finite element method (FEM) is proposed. The modal analysis is selected to calculate the resonant frequency of the harvester, and harmonic analysis is performed to investigate the influence of the geometric parameters on the output voltage. Based on simulation results, a MEMS Pb(Zr,Ti)O₃ (PZT) cantilever array with an integrated large Si proof mass is designed and fabricated to improve output voltage and power. Test results show that the fabricated generator, with five cantilever beams (with unit dimensions of about 3 × 2.4 × 0.05 mm³) and an individual integrated Si mass dimension of about 8 × 12.4 × 0.5 mm³, produces a output power of 66.75 μW, or a power density of 5.19 μW∙mm⁻³∙g⁻² with an optimal resistive load of 220 kΩ from 5 m/s² vibration acceleration at its resonant frequency of 234.5 Hz. In view of high internal impedance characteristic of the PZT generator, an efficient autonomous power conditioning circuit, with the function of impedance matching, energy storage and voltage regulation, is then presented, finding that the efficiency of the energy storage is greatly improved and up to 64.95%. The proposed self-supplied energy generator with power conditioning circuit could provide a very promising complete power supply solution for wireless sensor node loads. Full article

(This article belongs to the Section Sensor Networks)

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720 KiB

Open AccessArticle

Characterization of Antimicrobial Resistance Patterns and Detection of Virulence Genes in Campylobacter Isolates in Italy

by Elisabetta Di Giannatale, Gabriella Di Serafino, Katiuscia Zilli, Alessandra Alessiani, Lorena Sacchini, Giuliano Garofolo, Giuseppe Aprea and Francesca Marotta

Sensors 2014, 14(2), 3308-3322; https://doi.org/10.3390/s140203308 - 19 Feb 2014

Cited by 54 | Viewed by 9032

Abstract

Campylobacter has developed resistance to several antimicrobial agents over the years, including macrolides, quinolones and fluoroquinolones, becoming a significant public health hazard. A total of 145 strains derived from raw milk, chicken faeces, chicken carcasses, cattle faeces and human faeces collected from various [...] Read more.

Campylobacter has developed resistance to several antimicrobial agents over the years, including macrolides, quinolones and fluoroquinolones, becoming a significant public health hazard. A total of 145 strains derived from raw milk, chicken faeces, chicken carcasses, cattle faeces and human faeces collected from various Italian regions, were screened for antimicrobial susceptibility, molecular characterization (SmaI pulsed-field gel electrophoresis) and detection of virulence genes (sequencing and DNA microarray analysis). The prevalence of C. jejuni and C. coli was 62.75% and 37.24% respectively. Antimicrobial susceptibility revealed a high level of resistance for ciprofloxacin (62.76%), tetracycline (55.86%) and nalidixic acid (55.17%). Genotyping of Campylobacter isolates using PFGE revealed a total of 86 unique SmaI patterns. Virulence gene profiles were determined using a new microbial diagnostic microarray composed of 70-mer oligonucleotide probes targeting genes implicated in Campylobacter pathogenicity. Correspondence between PFGE and microarray clusters was observed. Comparisons of PFGE and virulence profiles reflected the high genetic diversity of the strains examined, leading us to speculate different degrees of pathogenicity inside Campylobacter populations. Full article

(This article belongs to the Section Biosensors)

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Open AccessArticle

Vertical Dynamic Deflection Measurement in Concrete Beams with the Microsoft Kinect

by Xiaojuan Qi, Derek Lichti, Mamdouh El-Badry, Jacky Chow and Kathleen Ang

Sensors 2014, 14(2), 3293-3307; https://doi.org/10.3390/s140203293 - 19 Feb 2014

Cited by 22 | Viewed by 6804

Abstract

The Microsoft Kinect is arguably the most popular RGB-D camera currently on the market, partially due to its low cost. It offers many advantages for the measurement of dynamic phenomena since it can directly measure three-dimensional coordinates of objects at video frame rate [...] Read more.

The Microsoft Kinect is arguably the most popular RGB-D camera currently on the market, partially due to its low cost. It offers many advantages for the measurement of dynamic phenomena since it can directly measure three-dimensional coordinates of objects at video frame rate using a single sensor. This paper presents the results of an investigation into the development of a Microsoft Kinect-based system for measuring the deflection of reinforced concrete beams subjected to cyclic loads. New segmentation methods for object extraction from the Kinect’s depth imagery and vertical displacement reconstruction algorithms have been developed and implemented to reconstruct the time-dependent displacement of concrete beams tested in laboratory conditions. The results demonstrate that the amplitude and frequency of the vertical displacements can be reconstructed with submillimetre and milliHz-level precision and accuracy, respectively. Full article

(This article belongs to the Section Physical Sensors)

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232 KiB

Open AccessCommunication

Low False-Positives in an mLumin-Based Bimolecular Fluorescence Complementation System with a Bicistronic Expression Vector

by Shun Liu, Xiangyong Li, Jie Yang and Zhihong Zhang

Sensors 2014, 14(2), 3284-3292; https://doi.org/10.3390/s140203284 - 19 Feb 2014

Cited by 6 | Viewed by 6251

Abstract

The simplicity and sensitivity of the bimolecular fluorescence complementation (BiFC) assay make it a powerful tool to investigate protein-protein interactions (PPIs) in living cells. However, non-specific association of the fluorescent protein fragments in a BiFC system can complicate evaluation of PPIs. Here, we [...] Read more.

The simplicity and sensitivity of the bimolecular fluorescence complementation (BiFC) assay make it a powerful tool to investigate protein-protein interactions (PPIs) in living cells. However, non-specific association of the fluorescent protein fragments in a BiFC system can complicate evaluation of PPIs. Here, we introduced a bicistronic expression vector, pBudCE4.1, into an mLumin-based BiFC system, denoted as the BEVL-BiFC system. The BEVL-BiFC system achieved a 25-fold contrast in BiFC efficiency between positive (Fos/Jun) and negative (ΔFos/Jun) PPIs. The high BiFC efficiency was due to a low false-positive rate, where less than 2% of cells displayed BiFC in the negative control. K-Ras and its interactive proteins, Ras binding domain (RBD) of Raf-1 and Grb2 were used to confirm the accuracy of the BEVL-BiFC system. The results also provide direct evidence in individual cells that post-translational modification of K-Ras and its localization at the plasma membrane (PM) were not essential for the interaction of K-Ras and Raf-1, whereas the interaction of Grb2 and K-Ras did depend on the PM localization of K-Ras. Taken together, the BEVL-BiFC system was developed to reduce the false-positive phenomenon in BiFC assays, resulting in more robust and accurate measurement of PPIs in living cells. Full article

(This article belongs to the Section Biosensors)

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852 KiB

Open AccessArticle

Modelling of Impulsional pH Variations Using ChemFET-Based Microdevices: Application to Hydrogen Peroxide Detection

by Abdou Karim Diallo, Lyes Djeghlaf, Jerome Launay and Pierre Temple-Boyer

Sensors 2014, 14(2), 3267-3283; https://doi.org/10.3390/s140203267 - 19 Feb 2014

Cited by 4 | Viewed by 6474

Abstract

This work presents the modelling of impulsional pH variations in microvolume related to water-based electrolysis and hydrogen peroxide electrochemical oxidation using an Electrochemical Field Effect Transistor (ElecFET) microdevice. This ElecFET device consists of a pH-Chemical FET (pH-ChemFET) with an integrated microelectrode around the [...] Read more.

This work presents the modelling of impulsional pH variations in microvolume related to water-based electrolysis and hydrogen peroxide electrochemical oxidation using an Electrochemical Field Effect Transistor (ElecFET) microdevice. This ElecFET device consists of a pH-Chemical FET (pH-ChemFET) with an integrated microelectrode around the dielectric gate area in order to trigger electrochemical reactions. Combining oxidation/reduction reactions on the microelectrode, water self-ionization and diffusion properties of associated chemical species, the model shows that the sensor response depends on the main influential parameters such as: (i) polarization parameters on the microelectrode, i.e., voltage (V_p) and time (t_p); (ii) distance between the gate sensitive area and the microelectrode (d); and (iii) hydrogen peroxide concentration ([H₂O₂]). The model developed can predict the ElecFET response behaviour and creates new opportunities for H₂O₂-based enzymatic detection of biomolecules. Full article

(This article belongs to the Section Chemical Sensors)

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