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Sensors, Volume 12, Issue 2 (February 2012) – 65 articles , Pages 1130-2350

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393 KiB  
Article
NIR Monitoring of Ammonia in Anaerobic Digesters Using a Diffuse Reflectance Probe
by Chitra S. Raju, Mette Marie Løkke, Sutaryo Sutaryo, Alastair J. Ward and Henrik B. Møller
Sensors 2012, 12(2), 2340-2350; https://doi.org/10.3390/s120202340 - 21 Feb 2012
Cited by 15 | Viewed by 7276
Abstract
The feasibility of using a diffuse reflectance probe attached to a near infrared spectrometer to monitor the total ammonia nitrogen (TAN) content in an anaerobic digester run on cattle manure was investigated; as a previous study has indicated that this probe can be [...] Read more.
The feasibility of using a diffuse reflectance probe attached to a near infrared spectrometer to monitor the total ammonia nitrogen (TAN) content in an anaerobic digester run on cattle manure was investigated; as a previous study has indicated that this probe can be easily attached to an anaerobic digester. Multivariate modelling techniques such as partial least squares regression and interval partial least squares methods were used to build models. Various data pre-treatments were applied to improve the models. The TAN concentrations measured were in the range of 1.5 to 5.5 g/L. An R2 of 0.91 with an RMSEP of 0.32 was obtained implying that the probe could be used for monitoring and screening purposes. Full article
(This article belongs to the Section Chemical Sensors)
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548 KiB  
Article
A Bioanalytical Platform for Simultaneous Detection and Quantification of Biological Toxins
by Oliver G. Weingart, Hui Gao, François Crevoisier, Friedrich Heitger, Marc-André Avondet and Hans Sigrist
Sensors 2012, 12(2), 2324-2339; https://doi.org/10.3390/s120202324 - 21 Feb 2012
Cited by 30 | Viewed by 11150
Abstract
Prevalent incidents support the notion that toxins, produced by bacteria, fungi, plants or animals are increasingly responsible for food poisoning or intoxication. Owing to their high toxicity some toxins are also regarded as potential biological warfare agents. Accordingly, control, detection and neutralization of [...] Read more.
Prevalent incidents support the notion that toxins, produced by bacteria, fungi, plants or animals are increasingly responsible for food poisoning or intoxication. Owing to their high toxicity some toxins are also regarded as potential biological warfare agents. Accordingly, control, detection and neutralization of toxic substances are a considerable economic burden to food safety, health care and military biodefense. The present contribution describes a new versatile instrument and related procedures for array-based simultaneous detection of bacterial and plant toxins using a bioanalytical platform which combines the specificity of covalently immobilized capture probes with a dedicated instrumentation and immuno-based microarray analytics. The bioanalytical platform consists of a microstructured polymer slide serving both as support of printed arrays and as incubation chamber. The platform further includes an easy-to-operate instrument for simultaneous slide processing at selectable assay temperature. Cy5 coupled streptavidin is used as unifying fluorescent tracer. Fluorescence image analysis and signal quantitation allow determination of the toxin’s identity and concentration. The system’s performance has been investigated by immunological detection of Botulinum Neurotoxin type A (BoNT/A), Staphylococcal enterotoxin B (SEB), and the plant toxin ricin. Toxins were detectable at levels as low as 0.5–1 ng·mL−1 in buffer or in raw milk. Full article
(This article belongs to the Special Issue Bioassays)
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939 KiB  
Article
Design and Implementation of an Omni-Directional Underwater Acoustic Micro-Modem Based on a Low-Power Micro-Controller Unit
by Tae-Hee Won and Sung-Joon Park
Sensors 2012, 12(2), 2309-2323; https://doi.org/10.3390/s120202309 - 20 Feb 2012
Cited by 29 | Viewed by 12039
Abstract
For decades, underwater acoustic communication has been restricted to the point-to-point long distance applications such as deep sea probes and offshore oil fields. For this reason, previous acoustic modems were typically characterized by high data rates and long working ranges at the expense [...] Read more.
For decades, underwater acoustic communication has been restricted to the point-to-point long distance applications such as deep sea probes and offshore oil fields. For this reason, previous acoustic modems were typically characterized by high data rates and long working ranges at the expense of large size and high power consumption. Recently, as the need for underwater wireless sensor networks (UWSNs) has increased, the research and development of compact and low-power consuming communication devices has become the focus. From the consideration that the requisites of acoustic modems for UWSNs are low power consumption, omni-directional beam pattern, low cost and so on, in this paper, we design and implement an omni-directional underwater acoustic micro-modem satisfying these requirements. In order to execute fast digital domain signal processing and support flexible interfaces with other peripherals, an ARM Cortex-M3 is embedded in the micro-modem. Also, for the realization of small and omni-directional properties, a spherical transducer having a resonant frequency of 70 kHz and a diameter of 34 mm is utilized for the implementation. Physical layer frame format and symbol structure for efficient packet-based underwater communication systems are also investigated. The developed acoustic micro-modem is verified analytically and experimentally in indoor and outdoor environments in terms of functionality and performance. Since the modem satisfies the requirements for use in UWSNs, it could be deployed in a wide range of applications requiring underwater acoustic communication. Full article
(This article belongs to the Special Issue Underwater Sensor Nodes and Underwater Sensor Networks)
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611 KiB  
Review
Biomarker Discovery by Novel Sensors Based on Nanoproteomics Approaches
by Noelia Dasilva, Paula Díez, Sergio Matarraz, María González-González, Sara Paradinas, Alberto Orfao and Manuel Fuentes
Sensors 2012, 12(2), 2284-2308; https://doi.org/10.3390/s120202284 - 16 Feb 2012
Cited by 47 | Viewed by 10910
Abstract
During the last years, proteomics has facilitated biomarker discovery by coupling high-throughput techniques with novel nanosensors. In the present review, we focus on the study of label-based and label-free detection systems, as well as nanotechnology approaches, indicating their advantages and applications in biomarker [...] Read more.
During the last years, proteomics has facilitated biomarker discovery by coupling high-throughput techniques with novel nanosensors. In the present review, we focus on the study of label-based and label-free detection systems, as well as nanotechnology approaches, indicating their advantages and applications in biomarker discovery. In addition, several disease biomarkers are shown in order to display the clinical importance of the improvement of sensitivity and selectivity by using nanoproteomics approaches as novel sensors. Full article
(This article belongs to the Special Issue Biomarkers and Nanosensors: New Approaches for Biology and Medicine)
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595 KiB  
Review
Gait Analysis Using Wearable Sensors
by Weijun Tao, Tao Liu, Rencheng Zheng and Hutian Feng
Sensors 2012, 12(2), 2255-2283; https://doi.org/10.3390/s120202255 - 16 Feb 2012
Cited by 888 | Viewed by 65887
Abstract
Gait analysis using wearable sensors is an inexpensive, convenient, and efficient manner of providing useful information for multiple health-related applications. As a clinical tool applied in the rehabilitation and diagnosis of medical conditions and sport activities, gait analysis using wearable sensors shows great [...] Read more.
Gait analysis using wearable sensors is an inexpensive, convenient, and efficient manner of providing useful information for multiple health-related applications. As a clinical tool applied in the rehabilitation and diagnosis of medical conditions and sport activities, gait analysis using wearable sensors shows great prospects. The current paper reviews available wearable sensors and ambulatory gait analysis methods based on the various wearable sensors. After an introduction of the gait phases, the principles and features of wearable sensors used in gait analysis are provided. The gait analysis methods based on wearable sensors is divided into gait kinematics, gait kinetics, and electromyography. Studies on the current methods are reviewed, and applications in sports, rehabilitation, and clinical diagnosis are summarized separately. With the development of sensor technology and the analysis method, gait analysis using wearable sensors is expected to play an increasingly important role in clinical applications. Full article
(This article belongs to the Section Physical Sensors)
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3524 KiB  
Review
Respiratory Physiology and the Impact of Different Modes of Ventilation on the Photoplethysmographic Waveform
by Aymen A. Alian and Kirk H. Shelley
Sensors 2012, 12(2), 2236-2254; https://doi.org/10.3390/s120202236 - 16 Feb 2012
Cited by 16 | Viewed by 11366
Abstract
The photoplethysmographic waveform sits at the core of the most used, and arguably the most important, clinical monitor, the pulse oximeter. Interestingly, the pulse oximeter was discovered while examining an artifact during the development of a noninvasive cardiac output monitor. This article will [...] Read more.
The photoplethysmographic waveform sits at the core of the most used, and arguably the most important, clinical monitor, the pulse oximeter. Interestingly, the pulse oximeter was discovered while examining an artifact during the development of a noninvasive cardiac output monitor. This article will explore the response of the pulse oximeter waveform to various modes of ventilation. Modern digital signal processing is allowing for a re-examination of this ubiquitous signal. The effect of ventilation on the photoplethysmographic waveform has long been thought of as a source of artifact. The primary goal of this article is to improve the understanding of the underlying physiology responsible for the observed phenomena, thereby encouraging the utilization of this understanding to develop new methods of patient monitoring. The reader will be presented with a review of respiratory physiology followed by numerous examples of the impact of ventilation on the photoplethysmographic waveform. Full article
(This article belongs to the Special Issue Optical Sensors in Medicine)
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2109 KiB  
Article
Improving Planetary Rover Attitude Estimation via MEMS Sensor Characterization
by Javier Hidalgo, Pantelis Poulakis, Johan Köhler, Jaime Del-Cerro and Antonio Barrientos
Sensors 2012, 12(2), 2219-2235; https://doi.org/10.3390/s120202219 - 15 Feb 2012
Cited by 17 | Viewed by 10031
Abstract
Micro Electro-Mechanical Systems (MEMS) are currently being considered in the space sector due to its suitable level of performance for spacecrafts in terms of mechanical robustness with low power consumption, small mass and size, and significant advantage in system design and accommodation. However, [...] Read more.
Micro Electro-Mechanical Systems (MEMS) are currently being considered in the space sector due to its suitable level of performance for spacecrafts in terms of mechanical robustness with low power consumption, small mass and size, and significant advantage in system design and accommodation. However, there is still a lack of understanding regarding the performance and testing of these new sensors, especially in planetary robotics. This paper presents what is missing in the field: a complete methodology regarding the characterization and modeling of MEMS sensors with direct application. A reproducible and complete approach including all the intermediate steps, tools and laboratory equipment is described. The process of sensor error characterization and modeling through to the final integration in the sensor fusion scheme is explained with detail. Although the concept of fusion is relatively easy to comprehend, carefully characterizing and filtering sensor information is not an easy task and is essential for good performance. The strength of the approach has been verified with representative tests of novel high-grade MEMS inertia sensors and exemplary planetary rover platforms with promising results. Full article
(This article belongs to the Special Issue Modeling, Testing and Reliability Issues in MEMS Engineering 2011)
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648 KiB  
Article
Near Infrared Characterization of Hetero-Core Optical Fiber SPR Sensors Coated with Ta2O5 Film and Their Applications
by Keiju Takagi and Kazuhiro Watanabe
Sensors 2012, 12(2), 2208-2218; https://doi.org/10.3390/s120202208 - 15 Feb 2012
Cited by 27 | Viewed by 9084
Abstract
This paper describes the characteristics of optical fiber sensors with surface plasmon resonance (SPR) at 1,310 nm in which the scattering loss of silica optical fiber is low. SPR operation in the infrared wavelength range is achieved by coating a thin tantalum pentaoxide [...] Read more.
This paper describes the characteristics of optical fiber sensors with surface plasmon resonance (SPR) at 1,310 nm in which the scattering loss of silica optical fiber is low. SPR operation in the infrared wavelength range is achieved by coating a thin tantalum pentaoxide (Ta2O5) film. The novelty of this paper lies in the verification of how the hetero-core scheme could be operated as a commercial base candidate in the sense of easy fabrication, sufficient mechanical strength, and significant sensitivity as a liquid detector under the basis of a low loss transmission network in the near infrared wavelength region. The effect of Ta2O5 layer thickness has been experimentally revealed in the wavelength region extending to 1,800 nm by using the hetero-core structured optical fiber. SPR characterizations have been made in the wavelength region 1,000–1,300 nm, showing the feasible operation at the near infrared wavelength and the possible practical applications. In addition, the technique developed in this work has been interestingly applied to a multi-point water-detection and a water-level gauge in which tandem-connected SPR sensors system using hetero-core structured fibers were incorporated. The detailed performance characteristics are also shown on these applications. Full article
(This article belongs to the Special Issue Optical Fiber Sensors 2012)
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814 KiB  
Article
A Survey on Virtualization of Wireless Sensor Networks
by Md. Motaharul Islam, Mohammad Mehedi Hassan, Ga-Won Lee and Eui-Nam Huh
Sensors 2012, 12(2), 2175-2207; https://doi.org/10.3390/s120202175 - 15 Feb 2012
Cited by 90 | Viewed by 15200
Abstract
Wireless Sensor Networks (WSNs) are gaining tremendous importance thanks to their broad range of commercial applications such as in smart home automation, health-care and industrial automation. In these applications multi-vendor and heterogeneous sensor nodes are deployed. Due to strict administrative control over the [...] Read more.
Wireless Sensor Networks (WSNs) are gaining tremendous importance thanks to their broad range of commercial applications such as in smart home automation, health-care and industrial automation. In these applications multi-vendor and heterogeneous sensor nodes are deployed. Due to strict administrative control over the specific WSN domains, communication barriers, conflicting goals and the economic interests of different WSN sensor node vendors, it is difficult to introduce a large scale federated WSN. By allowing heterogeneous sensor nodes in WSNs to coexist on a shared physical sensor substrate, virtualization in sensor network may provide flexibility, cost effective solutions, promote diversity, ensure security and increase manageability. This paper surveys the novel approach of using the large scale federated WSN resources in a sensor virtualization environment. Our focus in this paper is to introduce a few design goals, the challenges and opportunities of research in the field of sensor network virtualization as well as to illustrate a current status of research in this field. This paper also presents a wide array of state-of-the art projects related to sensor network virtualization. Full article
(This article belongs to the Section Sensor Networks)
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366 KiB  
Article
A Highly Sensitive CMOS Digital Hall Sensor for Low Magnetic Field Applications
by Yue Xu, Hong-Bin Pan, Shu-Zhuan He and Li Li
Sensors 2012, 12(2), 2162-2174; https://doi.org/10.3390/s120202162 - 15 Feb 2012
Cited by 34 | Viewed by 9854
Abstract
Integrated CMOS Hall sensors have been widely used to measure magnetic fields. However, they are difficult to work with in a low magnetic field environment due to their low sensitivity and large offset. This paper describes a highly sensitive digital Hall sensor fabricated [...] Read more.
Integrated CMOS Hall sensors have been widely used to measure magnetic fields. However, they are difficult to work with in a low magnetic field environment due to their low sensitivity and large offset. This paper describes a highly sensitive digital Hall sensor fabricated in 0.18 μm high voltage CMOS technology for low field applications. The sensor consists of a switched cross-shaped Hall plate and a novel signal conditioner. It effectively eliminates offset and low frequency 1/f noise by applying a dynamic quadrature offset cancellation technique. The measured results show the optimal Hall plate achieves a high current related sensitivity of about 310 V/AT. The whole sensor has a remarkable ability to measure a minimum ±2 mT magnetic field and output a digital Hall signal in a wide temperature range from −40 °C to 120 °C. Full article
(This article belongs to the Section Physical Sensors)
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1319 KiB  
Communication
Objective Display and Discrimination of Floral Odors from Amorphophallus titanum, Bloomed on Different Dates and at Different Locations, Using an Electronic Nose
by Kouki Fujioka, Mika Shirasu, Yoshinobu Manome, Nobuo Ito, Satoshi Kakishima, Tomohiro Minami, Tadashi Tominaga, Fumio Shimozono, Takeo Iwamoto, Keiichi Ikeda, Kenji Yamamoto, Jin Murata and Yasuko Tomizawa
Sensors 2012, 12(2), 2152-2161; https://doi.org/10.3390/s120202152 - 15 Feb 2012
Cited by 23 | Viewed by 13592
Abstract
As olfactory perceptions vary from person to person, it is difficult to describe smells objectively. In contrast, electronic noses also detect smells with their sensors, but in addition describe those using electronic signals. Here we showed a virtual connection method between a human [...] Read more.
As olfactory perceptions vary from person to person, it is difficult to describe smells objectively. In contrast, electronic noses also detect smells with their sensors, but in addition describe those using electronic signals. Here we showed a virtual connection method between a human nose perceptions and electronic nose responses with the smell of standard gases. In this method, Amorphophallus titanum flowers, which emit a strong carrion smell, could objectively be described using an electronic nose, in a way resembling the skill of sommeliers. We could describe the flower smell to be close to that of a mixture of methyl mercaptan and propionic acid, by calculation of the dilution index from electronic resistances. In other words, the smell resembled that of “decayed cabbage, garlic and pungent sour” with possible descriptors. Additionally, we compared the smells of flowers which bloomed on different dates and at different locations and showed the similarity of odor intensities visually, in standard gas categories. We anticipate our assay to be a starting point for a perceptive connection between our noses and electronic noses. Full article
(This article belongs to the Special Issue Odor Detection: Electronic Nose, Olfactometer, and Advanced Instrumentation)
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960 KiB  
Review
Waveguide-Mode Sensors as Aptasensors
by Subash C. B. Gopinath, Koichi Awazu and Makoto Fujimaki
Sensors 2012, 12(2), 2136-2151; https://doi.org/10.3390/s120202136 - 15 Feb 2012
Cited by 45 | Viewed by 9202
Abstract
Aptamers are artificial nucleic acid ligands that can be generated by in vitro selection through partition and amplification. Aptamers can be generated against a wide range of biomolecules through the formation of versatile stem-loop structures. Because aptamers are potential substitutes for antibodies and [...] Read more.
Aptamers are artificial nucleic acid ligands that can be generated by in vitro selection through partition and amplification. Aptamers can be generated against a wide range of biomolecules through the formation of versatile stem-loop structures. Because aptamers are potential substitutes for antibodies and drugs, the development of an aptamer-based sensor (aptasensor) is mandatory for diagnosis. We previously reported that waveguide-mode sensors are useful in the analysis of a wide range of biomolecular interactions, including aptamers. The advantages of the waveguide-mode sensor that we developed include physical and chemical stability and that higher sensitivity can be achieved with ease by perforating the waveguide layer or using colored materials such as dyes or metal nanoparticles as labels. Herein, we provide an overview of the strategies and applications for aptamer-based analyses using waveguide-mode sensors. Full article
(This article belongs to the Special Issue Aptamer-Based Sensors)
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1803 KiB  
Article
Experimental Assessment of Different Receiver Structures for Underwater Acoustic Communications over Multipath Channels
by Guosong Zhang, Jens M. Hovem and Hefeng Dong
Sensors 2012, 12(2), 2118-2135; https://doi.org/10.3390/s120202118 - 14 Feb 2012
Cited by 6 | Viewed by 8219
Abstract
Underwater communication channels are often complicated, and in particular multipath propagation may cause intersymbol interference (ISI). This paper addresses how to remove ISI, and evaluates the performance of three different receiver structures and their implementations. Using real data collected in a high-frequency (10–14 [...] Read more.
Underwater communication channels are often complicated, and in particular multipath propagation may cause intersymbol interference (ISI). This paper addresses how to remove ISI, and evaluates the performance of three different receiver structures and their implementations. Using real data collected in a high-frequency (10–14 kHz) field experiment, the receiver structures are evaluated by off-line data processing. The three structures are multichannel decision feedback equalizer (DFE), passive time reversal receiver (passive-phase conjugation (PPC) with a single channel DFE), and the joint PPC with multichannel DFE. In sparse channels, dominant arrivals represent the channel information, and the matching pursuit (MP) algorithm which exploits the channel sparseness has been investigated for PPC processing. In the assessment, it is found that: (1) it is advantageous to obtain spatial gain using the adaptive multichannel combining scheme; and (2) the MP algorithm improves the performance of communications using PPC processing. Full article
(This article belongs to the Special Issue Underwater Sensor Nodes and Underwater Sensor Networks)
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4988 KiB  
Article
Investigation of the Transient Behavior of a Cantilever Beam Using PVDF Sensors
by Chien-Ching Ma, Yu-Hsi Huang and Shan-Ying Pan
Sensors 2012, 12(2), 2088-2117; https://doi.org/10.3390/s120202088 - 14 Feb 2012
Cited by 32 | Viewed by 9725
Abstract
In this paper, a PVDF film sensor was used to measure the transient responses of a cantilever beam subjected to an impact loading. The measurement capability of a PVDF sensor is affected by the area of the PVDF film sensor and the signal [...] Read more.
In this paper, a PVDF film sensor was used to measure the transient responses of a cantilever beam subjected to an impact loading. The measurement capability of a PVDF sensor is affected by the area of the PVDF film sensor and the signal conditioner (charge amplifier). The influences of these effects on the experimental measurements were investigated. The transient responses for the dynamic strain of the beam were measured simultaneously by the PVDF sensor and a conventional strain gauge. The resonant frequencies of the beam were determined by applying the Fast Fourier Transform on transient results in the time domain of the PVDF sensor and the strain gauge. The experimentally measured resonant frequencies from the PVDF sensor and the strain gauge were compared with those predicted from theoretical and FEM numerical calculations. Based on the comparison of the results measured for these two sensors, the PVDF film sensor proved capable of measuring transient responses for dynamic strain, and its sensitivity is better than that of the strain gauge. Furthermore, almost all the resonant frequencies can be obtained from the results of transient responses for PVDF film. Full article
(This article belongs to the Section Physical Sensors)
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420 KiB  
Article
Architecture and Protocol of a Semantic System Designed for Video Tagging with Sensor Data in Mobile Devices
by Elsa Macias, Jaime Lloret, Alvaro Suarez and Miguel Garcia
Sensors 2012, 12(2), 2062-2087; https://doi.org/10.3390/s120202062 - 14 Feb 2012
Cited by 8 | Viewed by 10453
Abstract
Current mobile phones come with several sensors and powerful video cameras. These video cameras can be used to capture good quality scenes, which can be complemented with the information gathered by the sensors also embedded in the phones. For example, the surroundings of [...] Read more.
Current mobile phones come with several sensors and powerful video cameras. These video cameras can be used to capture good quality scenes, which can be complemented with the information gathered by the sensors also embedded in the phones. For example, the surroundings of a beach recorded by the camera of the mobile phone, jointly with the temperature of the site can let users know via the Internet if the weather is nice enough to swim. In this paper, we present a system that tags the video frames of the video recorded from mobile phones with the data collected by the embedded sensors. The tagged video is uploaded to a video server, which is placed on the Internet and is accessible by any user. The proposed system uses a semantic approach with the stored information in order to make easy and efficient video searches. Our experimental results show that it is possible to tag video frames in real time and send the tagged video to the server with very low packet delay variations. As far as we know there is not any other application developed as the one presented in this paper. Full article
(This article belongs to the Special Issue Ubiquitous Sensing)
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680 KiB  
Review
Localization Algorithms of Underwater Wireless Sensor Networks: A Survey
by Guangjie Han, Jinfang Jiang, Lei Shu, Yongjun Xu and Feng Wang
Sensors 2012, 12(2), 2026-2061; https://doi.org/10.3390/s120202026 - 13 Feb 2012
Cited by 172 | Viewed by 16644
Abstract
In Underwater Wireless Sensor Networks (UWSNs), localization is one of most important technologies since it plays a critical role in many applications. Motivated by widespread adoption of localization, in this paper, we present a comprehensive survey of localization algorithms. First, we classify localization [...] Read more.
In Underwater Wireless Sensor Networks (UWSNs), localization is one of most important technologies since it plays a critical role in many applications. Motivated by widespread adoption of localization, in this paper, we present a comprehensive survey of localization algorithms. First, we classify localization algorithms into three categories based on sensor nodes’ mobility: stationary localization algorithms, mobile localization algorithms and hybrid localization algorithms. Moreover, we compare the localization algorithms in detail and analyze future research directions of localization algorithms in UWSNs. Full article
(This article belongs to the Special Issue Underwater Sensor Nodes and Underwater Sensor Networks)
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159 KiB  
Article
Highly Sensitive Detection of Naphthalene in Solvent Vapor Using a Functionalized PBG Refractive Index Sensor
by Maiko Girschikofsky, Manuel Rosenberger, Stefan Belle, Malte Brutschy, Siegfried R. Waldvogel and Ralf Hellmann
Sensors 2012, 12(2), 2018-2025; https://doi.org/10.3390/s120202018 - 13 Feb 2012
Cited by 24 | Viewed by 8419
Abstract
We report an optical refractive index sensor system based on a planar Bragg grating which is functionalized by substituted γ-cyclodextrin to determine low concentrations of naphthalene in solvent vapor. The sensor system exhibits a quasi-instantaneous shift of the Bragg wavelength and is therefore [...] Read more.
We report an optical refractive index sensor system based on a planar Bragg grating which is functionalized by substituted γ-cyclodextrin to determine low concentrations of naphthalene in solvent vapor. The sensor system exhibits a quasi-instantaneous shift of the Bragg wavelength and is therefore capable for online detection. The overall shift of the Bragg wavelength reveals a linear relationship to the analyte concentration with a gradient of 12.5 ± 1.5 pm/ppm. Due to the spectral resolution and repeatability of the interrogation system, this corresponds to acquisition steps of 80 ppb. Taking into account the experimentally detected signal noise a minimum detection limit of 0.48 ± 0.05 ppm is deduced. Full article
(This article belongs to the Section Chemical Sensors)
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1148 KiB  
Article
A Method Based on Multi-Sensor Data Fusion for Fault Detection of Planetary Gearboxes
by Yaguo Lei, Jing Lin, Zhengjia He and Detong Kong
Sensors 2012, 12(2), 2005-2017; https://doi.org/10.3390/s120202005 - 10 Feb 2012
Cited by 100 | Viewed by 11327
Abstract
Studies on fault detection and diagnosis of planetary gearboxes are quite limited compared with those of fixed-axis gearboxes. Different from fixed-axis gearboxes, planetary gearboxes exhibit unique behaviors, which invalidate fault diagnosis methods that work well for fixed-axis gearboxes. It is a fact that [...] Read more.
Studies on fault detection and diagnosis of planetary gearboxes are quite limited compared with those of fixed-axis gearboxes. Different from fixed-axis gearboxes, planetary gearboxes exhibit unique behaviors, which invalidate fault diagnosis methods that work well for fixed-axis gearboxes. It is a fact that for systems as complex as planetary gearboxes, multiple sensors mounted on different locations provide complementary information on the health condition of the systems. On this basis, a fault detection method based on multi-sensor data fusion is introduced in this paper. In this method, two features developed for planetary gearboxes are used to characterize the gear health conditions, and an adaptive neuro-fuzzy inference system (ANFIS) is utilized to fuse all features from different sensors. In order to demonstrate the effectiveness of the proposed method, experiments are carried out on a planetary gearbox test rig, on which multiple accelerometers are mounted for data collection. The comparisons between the proposed method and the methods based on individual sensors show that the former achieves much higher accuracies in detecting planetary gearbox faults. Full article
(This article belongs to the Section Physical Sensors)
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1973 KiB  
Article
Robust Kernel-Based Tracking with Multiple Subtemplates in Vision Guidance System
by Yuzhuang Yan, Xinsheng Huang, Wanying Xu and Lurong Shen
Sensors 2012, 12(2), 1990-2004; https://doi.org/10.3390/s120201990 - 10 Feb 2012
Cited by 7 | Viewed by 6246
Abstract
The mean shift algorithm has achieved considerable success in target tracking due to its simplicity and robustness. However, the lack of spatial information may result in its failure to get high tracking precision. This might be even worse when the target is scale [...] Read more.
The mean shift algorithm has achieved considerable success in target tracking due to its simplicity and robustness. However, the lack of spatial information may result in its failure to get high tracking precision. This might be even worse when the target is scale variant and the sequences are gray-levels. This paper presents a novel multiple subtemplates based tracking algorithm for the terminal guidance application. By applying a separate tracker to each subtemplate, it can handle more complicated situations such as rotation, scaling, and partial coverage of the target. The innovations include: (1) an optimal subtemplates selection algorithm is designed, which ensures that the selected subtemplates maximally represent the information of the entire template while having the least mutual redundancy; (2) based on the serial tracking results and the spatial constraint prior to those subtemplates, a Gaussian weighted voting method is proposed to locate the target center; (3) the optimal scale factor is determined by maximizing the voting results among the scale searching layers, which avoids the complicated threshold setting problem. Experiments on some videos with static scenes show that the proposed method greatly improves the tracking accuracy compared to the original mean shift algorithm. Full article
(This article belongs to the Section Physical Sensors)
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1178 KiB  
Article
Secure Cooperation of Autonomous Mobile Sensors Using an Underwater Acoustic Network
by Andrea Caiti, Vincenzo Calabrò, Gianluca Dini, Angelica Lo Duca and Andrea Munafò
Sensors 2012, 12(2), 1967-1989; https://doi.org/10.3390/s120201967 - 10 Feb 2012
Cited by 50 | Viewed by 10189
Abstract
Methodologies and algorithms are presented for the secure cooperation of a team of autonomous mobile underwater sensors, connected through an acoustic communication network, within surveillance and patrolling applications. In particular, the work proposes a cooperative algorithm in which the mobile underwater sensors (installed [...] Read more.
Methodologies and algorithms are presented for the secure cooperation of a team of autonomous mobile underwater sensors, connected through an acoustic communication network, within surveillance and patrolling applications. In particular, the work proposes a cooperative algorithm in which the mobile underwater sensors (installed on Autonomous Underwater Vehicles—AUVs) respond to simple local rules based on the available information to perform the mission and maintain the communication link with the network (behavioral approach). The algorithm is intrinsically robust: with loss of communication among the vehicles the coverage performance (i.e., the mission goal) is degraded but not lost. The ensuing form of graceful degradation provides also a reactive measure against Denial of Service. The cooperative algorithm relies on the fact that the available information from the other sensors, though not necessarily complete, is trustworthy. To ensure trustworthiness, a security suite has been designed, specifically oriented to the underwater scenario, and in particular with the goal of reducing the communication overhead introduced by security in terms of number and size of messages. The paper gives implementation details on the integration between the security suite and the cooperative algorithm and provides statistics on the performance of the system as collected during the UAN project sea trial held in Trondheim, Norway, in May 2011. Full article
(This article belongs to the Special Issue Underwater Sensor Nodes and Underwater Sensor Networks)
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2070 KiB  
Article
Electrical Model of a Carbon-Polymer Composite (CPC) Collision Detector
by Karl Kruusamäe, Andres Punning and Alvo Aabloo
Sensors 2012, 12(2), 1950-1966; https://doi.org/10.3390/s120201950 - 10 Feb 2012
Cited by 11 | Viewed by 8052
Abstract
We present a study of an electrical model of electromechanically active carbon-polymer composite (CPC) with carbide-derived carbon (CDC) electrodes. The major focus is on investigation of surface electrode behavior upon external bending of the material. We show that electrical impedance measured from the [...] Read more.
We present a study of an electrical model of electromechanically active carbon-polymer composite (CPC) with carbide-derived carbon (CDC) electrodes. The major focus is on investigation of surface electrode behavior upon external bending of the material. We show that electrical impedance measured from the surface of the CDC-based CPC can be used to determine the curvature of the material and, hence, the tip displacement of a CPC laminate in a cantilever configuration. It is also shown that by measuring surface signals in the process of an actuator’s work-cycle, we obtain a self-sensing collision-detecting CPC actuator that can be considered as a counterpart of biomimetic vibrissae. Full article
(This article belongs to the Special Issue Biomimetic Sensors, Actuators and Integrated Systems)
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1452 KiB  
Article
Sunlight Intensity Based Global Positioning System for Near-Surface Underwater Sensors
by Javier V. Gómez, Frode E. Sandnes and Borja Fernández
Sensors 2012, 12(2), 1930-1949; https://doi.org/10.3390/s120201930 - 10 Feb 2012
Cited by 8 | Viewed by 11573
Abstract
Water monitoring is important in domains including documenting climate change, weather prediction and fishing. This paper presents a simple and energy efficient localization strategy for near surface buoy based sensors. Sensors can be dropped randomly in the ocean and thus self-calibrate in terms [...] Read more.
Water monitoring is important in domains including documenting climate change, weather prediction and fishing. This paper presents a simple and energy efficient localization strategy for near surface buoy based sensors. Sensors can be dropped randomly in the ocean and thus self-calibrate in terms of geographic location such that geo-tagged observations of water quality can be made without the need for costly and energy consuming GPS-hardware. The strategy is based on nodes with an accurate clock and light sensors that can regularly sample the level of light intensity. The measurements are fitted into a celestial model of the earth motion around the sun. By identifying the trajectory of the sun across the skies one can accurately determine sunrise and sunset times, and thus extract the longitude and latitude of the sensor. Unlike previous localization techniques for underwater sensors, the current approach does not rely on stationary or mobile reference points. Full article
(This article belongs to the Special Issue Underwater Sensor Nodes and Underwater Sensor Networks)
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351 KiB  
Article
The Effect of Direction on Cursor Moving Kinematics
by Ling-Fu Meng, Hsin-Yung Chen, Chiu-Ping Lu, Ming-Chung Chen and Chi-Nung Chu
Sensors 2012, 12(2), 1919-1929; https://doi.org/10.3390/s120201919 - 10 Feb 2012
Cited by 1 | Viewed by 6413
Abstract
There have been only few studies to substantiate the kinematic characteristics of cursor movement. In this study, a quantitative experimental research method was used to explore the effect of moving direction on the kinematics of cursor movement in 24 typical young persons using [...] Read more.
There have been only few studies to substantiate the kinematic characteristics of cursor movement. In this study, a quantitative experimental research method was used to explore the effect of moving direction on the kinematics of cursor movement in 24 typical young persons using our previously developed computerized measuring program. The results of multiple one way repeated measures ANOVAs and post hoc LSD tests demonstrated that the moving direction had effects on average velocity, movement time, movement unit and peak velocity. Moving leftward showed better efficiency than moving rightward, upward and downward from the kinematic evidences such as velocity, movement unit and time. Moreover, the unique pattern of the power spectral density (PSD) of velocity (strategy for power application) explained why the smoothness was still maintained while moving leftward even under an unstable situation with larger momentum. Moreover, the information from this cursor moving study can guide us to relocate the toolbars and icons in the window interface, especially for individuals with physical disabilities whose performances are easily interrupted while controlling the cursor in specific directions. Full article
(This article belongs to the Section Physical Sensors)
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867 KiB  
Review
Fiber Bragg Grating Sensors for Harsh Environments
by Stephen J. Mihailov
Sensors 2012, 12(2), 1898-1918; https://doi.org/10.3390/s120201898 - 10 Feb 2012
Cited by 726 | Viewed by 29883
Abstract
Because of their small size, passive nature, immunity to electromagnetic interference, and capability to directly measure physical parameters such as temperature and strain, fiber Bragg grating sensors have developed beyond a laboratory curiosity and are becoming a mainstream sensing technology. Recently, high temperature [...] Read more.
Because of their small size, passive nature, immunity to electromagnetic interference, and capability to directly measure physical parameters such as temperature and strain, fiber Bragg grating sensors have developed beyond a laboratory curiosity and are becoming a mainstream sensing technology. Recently, high temperature stable gratings based on regeneration techniques and femtosecond infrared laser processing have shown promise for use in extreme environments such as high temperature, pressure or ionizing radiation. Such gratings are ideally suited for energy production applications where there is a requirement for advanced energy system instrumentation and controls that are operable in harsh environments. This paper will present a review of some of the more recent developments. Full article
(This article belongs to the Special Issue Optical Fiber Sensors 2012)
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755 KiB  
Article
Gen-2 Hand-Held Optical Imager towards Cancer Imaging: Reflectance and Transillumination Phantom Studies
by Jean Gonzalez, Manuela Roman, Michael Hall and Anuradha Godavarty
Sensors 2012, 12(2), 1885-1897; https://doi.org/10.3390/s120201885 - 10 Feb 2012
Cited by 15 | Viewed by 7734
Abstract
Hand-held near-infrared (NIR) optical imagers are developed by various researchers towards non-invasive clinical breast imaging. Unlike these existing imagers that can perform only reflectance imaging, a generation-2 (Gen-2) hand-held optical imager has been recently developed to perform both reflectance and transillumination imaging. The [...] Read more.
Hand-held near-infrared (NIR) optical imagers are developed by various researchers towards non-invasive clinical breast imaging. Unlike these existing imagers that can perform only reflectance imaging, a generation-2 (Gen-2) hand-held optical imager has been recently developed to perform both reflectance and transillumination imaging. The unique forked design of the hand-held probe head(s) allows for reflectance imaging (as in ultrasound) and transillumination or compressed imaging (as in X-ray mammography). Phantom studies were performed to demonstrate two-dimensional (2D) target detection via reflectance and transillumination imaging at various target depths (1–5 cm deep) and using simultaneous multiple point illumination approach. It was observed that 0.45 cc targets were detected up to 5 cm deep during transillumination, but limited to 2.5 cm deep during reflectance imaging. Additionally, implementing appropriate data post-processing techniques along with a polynomial fitting approach, to plot 2D surface contours of the detected signal, yields distinct target detectability and localization. The ability of the gen-2 imager to perform both reflectance and transillumination imaging allows its direct comparison to ultrasound and X-ray mammography results, respectively, in future clinical breast imaging studies. Full article
(This article belongs to the Special Issue Optical Sensors in Medicine)
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1008 KiB  
Article
Parametric Dense Stereovision Implementation on a System-on Chip (SoC)
by Alfredo Gardel, Pablo Montejo, Jorge García, Ignacio Bravo and José L. Lázaro
Sensors 2012, 12(2), 1863-1884; https://doi.org/10.3390/s120201863 - 10 Feb 2012
Cited by 8 | Viewed by 8120
Abstract
This paper proposes a novel hardware implementation of a dense recovery of stereovision 3D measurements. Traditionally 3D stereo systems have imposed the maximum number of stereo correspondences, introducing a large restriction on artificial vision algorithms. The proposed system-on-chip (SoC) provides great performance and [...] Read more.
This paper proposes a novel hardware implementation of a dense recovery of stereovision 3D measurements. Traditionally 3D stereo systems have imposed the maximum number of stereo correspondences, introducing a large restriction on artificial vision algorithms. The proposed system-on-chip (SoC) provides great performance and efficiency, with a scalable architecture available for many different situations, addressing real time processing of stereo image flow. Using double buffering techniques properly combined with pipelined processing, the use of reconfigurable hardware achieves a parametrisable SoC which gives the designer the opportunity to decide its right dimension and features. The proposed architecture does not need any external memory because the processing is done as image flow arrives. Our SoC provides 3D data directly without the storage of whole stereo images. Our goal is to obtain high processing speed while maintaining the accuracy of 3D data using minimum resources. Configurable parameters may be controlled by later/parallel stages of the vision algorithm executed on an embedded processor. Considering hardware FPGA clock of 100 MHz, image flows up to 50 frames per second (fps) of dense stereo maps of more than 30,000 depth points could be obtained considering 2 Mpix images, with a minimum initial latency. The implementation of computer vision algorithms on reconfigurable hardware, explicitly low level processing, opens up the prospect of its use in autonomous systems, and they can act as a coprocessor to reconstruct 3D images with high density information in real time. Full article
(This article belongs to the Special Issue Microprocessors and System-on-Chip)
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1234 KiB  
Article
Extraction and Analysis of Impervious Surfaces Based on a Spectral Un-Mixing Method Using Pearl River Delta of China Landsat TM/ETM+ Imagery from 1998 to 2008
by Yingbin Deng, Fenglei Fan and Renrong Chen
Sensors 2012, 12(2), 1846-1862; https://doi.org/10.3390/s120201846 - 9 Feb 2012
Cited by 46 | Viewed by 8703
Abstract
Impervious surface area (ISA) is considered as an indicator of environment change and is regarded as an important input parameter for hydrological cycle simulation, water management and area pollution assessment. The Pearl River Delta (PRD), the 3rd most important economic district of China, [...] Read more.
Impervious surface area (ISA) is considered as an indicator of environment change and is regarded as an important input parameter for hydrological cycle simulation, water management and area pollution assessment. The Pearl River Delta (PRD), the 3rd most important economic district of China, is chosen in this paper to extract the ISA information based on Landsat images of 1998, 2003 and 2008 by using a linear spectral un-mixing method and to monitor impervious surface change by analyzing the multi-temporal Landsat-derived fractional impervious surface. Results of this study were as follows: (1) the area of ISA in the PRD increased 79.09% from 1998 to 2003 and 26.88% from 2003 to 2008 separately; (2) the spatial distribution of ISA was described according to the 1998/2003 percentage respectively. Most of middle and high percentage ISA was located in northwestern and southeastern of the whole delta, and middle percentage ISA was mainly located in the city interior, high percentage ISA was mainly located in the suburban around the city accordingly; (3) the expanding direction and trend of high percentage ISA was discussed in order to understand the change of urban in this delta; High percentage ISA moved from inner city to edge of urban area during 1998–2003 and moved to the suburban area that far from the urban area mixed with jumpily and gradually during 2003–2008. According to the discussion of high percentage ISA spatial expanded direction, it could be found out that high percentage ISA moved outward from the centre line of Pearl River of the whole delta while a high ISA percentage in both shores of the Pearl River Estuary moved toward the Pearl River; (4) combining the change of ISA with social conditions, the driving relationship was analyzed in detail. It was evident that ISA percentage change had a deep relationship with the economic development of this region in the past ten years. Contemporaneous major sport events (16th Asia Games of Guangzhou, 26th Summer Universidad of Shenzhen) and the government policies also promoted the development of the ISA. Meanwhile, topographical features like the National Nature Reserve of China restricted and affected the expansion of the ISA. Above all, this paper attempted to extract ISA in a major region of the PRD; the temporal and spatial analyses to PRD ISA demonstrated the drastic changes in developed areas of China. These results were important and valuable for land use management, ecological protection and policy establishment. Full article
(This article belongs to the Section Remote Sensors)
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383 KiB  
Article
AURP: An AUV-Aided Underwater Routing Protocol for Underwater Acoustic Sensor Networks
by Seokhoon Yoon, Abul K. Azad, Hoon Oh and Sunghwan Kim
Sensors 2012, 12(2), 1827-1845; https://doi.org/10.3390/s120201827 - 9 Feb 2012
Cited by 131 | Viewed by 12481
Abstract
Deploying a multi-hop underwater acoustic sensor network (UASN) in a large area brings about new challenges in reliable data transmissions and survivability of network due to the limited underwater communication range/bandwidth and the limited energy of underwater sensor nodes. In order to address [...] Read more.
Deploying a multi-hop underwater acoustic sensor network (UASN) in a large area brings about new challenges in reliable data transmissions and survivability of network due to the limited underwater communication range/bandwidth and the limited energy of underwater sensor nodes. In order to address those challenges and achieve the objectives of maximization of data delivery ratio and minimization of energy consumption of underwater sensor nodes, this paper proposes a new underwater routing scheme, namely AURP (AUV-aided underwater routing protocol), which uses not only heterogeneous acoustic communication channels but also controlled mobility of multiple autonomous underwater vehicles (AUVs). In AURP, the total data transmissions are minimized by using AUVs as relay nodes, which collect sensed data from gateway nodes and then forward to the sink. Moreover, controlled mobility of AUVs makes it possible to apply a short-range high data rate underwater channel for transmissions of a large amount of data. To the best to our knowledge, this work is the first attempt to employ multiple AUVs as relay nodes in a multi-hop UASN to improve the network performance in terms of data delivery ratio and energy consumption. Simulations, which are incorporated with a realistic underwater acoustic communication channel model, are carried out to evaluate the performance of the proposed scheme, and the results indicate that a high delivery ratio and low energy consumption can be achieved. Full article
(This article belongs to the Special Issue Underwater Sensor Nodes and Underwater Sensor Networks)
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924 KiB  
Article
Evaluation of Electrical and Optical Plethysmography Sensors for Noninvasive Monitoring of Hemoglobin Concentration
by Justin P. Phillips, Michelle Hickey and Panayiotis A. Kyriacou
Sensors 2012, 12(2), 1816-1826; https://doi.org/10.3390/s120201816 - 9 Feb 2012
Cited by 20 | Viewed by 10580
Abstract
Completely noninvasive monitoring of hemoglobin concentration has not yet been fully realized in the clinical setting. This study investigates the viability of measuring hemoglobin concentration noninvasively by evaluating the performance of two types of sensor using a tissue phantom perfused with a blood [...] Read more.
Completely noninvasive monitoring of hemoglobin concentration has not yet been fully realized in the clinical setting. This study investigates the viability of measuring hemoglobin concentration noninvasively by evaluating the performance of two types of sensor using a tissue phantom perfused with a blood substitute. An electrical sensor designed to measure blood volume changes during the cardiac cycle was used together with an infrared optical sensor for detection of erythrocyte-bound hemoglobin. Both sensors demonstrated sensitivity to changes in pulse volume (plethysmography). The electrical sensor produced a signal referred to as capacitance plethysmograph (CPG) a quantity which was invariant to the concentration of an infrared absorbing dye present in the blood substitute. The optical sensor signal (photoplethysmograph) increased in amplitude with increasing absorber concentration. The ratio PPG:CPG is invariant to pulse pressure. This quantity is discussed as a possible index of in vivo hemoglobin concentration. Full article
(This article belongs to the Special Issue Optical Sensors in Medicine)
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566 KiB  
Article
A Platform for Combined DNA and Protein Microarrays Based on Total Internal Reflection Fluorescence
by Alexander Asanov, Angélica Zepeda and Luis Vaca
Sensors 2012, 12(2), 1800-1815; https://doi.org/10.3390/s120201800 - 9 Feb 2012
Cited by 22 | Viewed by 9640
Abstract
We have developed a novel microarray technology based on total internal reflection fluorescence (TIRF) in combination with DNA and protein bioassays immobilized at the TIRF surface. Unlike conventional microarrays that exhibit reduced signal-to-background ratio, require several stages of incubation, rinsing and stringency control, [...] Read more.
We have developed a novel microarray technology based on total internal reflection fluorescence (TIRF) in combination with DNA and protein bioassays immobilized at the TIRF surface. Unlike conventional microarrays that exhibit reduced signal-to-background ratio, require several stages of incubation, rinsing and stringency control, and measure only end-point results, our TIRF microarray technology provides several orders of magnitude better signal-to-background ratio, performs analysis rapidly in one step, and measures the entire course of association and dissociation kinetics between target DNA and protein molecules and the bioassays. In many practical cases detection of only DNA or protein markers alone does not provide the necessary accuracy for diagnosing a disease or detecting a pathogen. Here we describe TIRF microarrays that detect DNA and protein markers simultaneously, which reduces the probabilities of false responses. Supersensitive and multiplexed TIRF DNA and protein microarray technology may provide a platform for accurate diagnosis or enhanced research studies. Our TIRF microarray system can be mounted on upright or inverted microscopes or interfaced directly with CCD cameras equipped with a single objective, facilitating the development of portable devices. As proof-of-concept we applied TIRF microarrays for detecting molecular markers from Bacillus anthracis, the pathogen responsible for anthrax. Full article
(This article belongs to the Special Issue Synthetic Fluorescent Indicators for Low Molecular Weight Organic Metabolites)
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