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Sensors, Volume 9, Issue 9 (September 2009) – 59 articles , Pages 6604-7579

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Article
Multi-Unmanned Aerial Vehicle (UAV) Cooperative Fault Detection Employing Differential Global Positioning (DGPS), Inertial and Vision Sensors
Sensors 2009, 9(9), 7566-7579; https://doi.org/10.3390/s90907566 - 24 Sep 2009
Cited by 60 | Viewed by 11474
Abstract
This paper presents a method to increase the reliability of Unmanned Aerial Vehicle (UAV) sensor Fault Detection and Identification (FDI) in a multi-UAV context. Differential Global Positioning System (DGPS) and inertial sensors are used for sensor FDI in each UAV. The method uses [...] Read more.
This paper presents a method to increase the reliability of Unmanned Aerial Vehicle (UAV) sensor Fault Detection and Identification (FDI) in a multi-UAV context. Differential Global Positioning System (DGPS) and inertial sensors are used for sensor FDI in each UAV. The method uses additional position estimations that augment individual UAV FDI system. These additional estimations are obtained using images from the same planar scene taken from two different UAVs. Since accuracy and noise level of the estimation depends on several factors, dynamic replanning of the multi-UAV team can be used to obtain a better estimation in case of faults caused by slow growing errors of absolute position estimation that cannot be detected by using local FDI in the UAVs. Experimental results with data from two real UAVs are also presented. Full article
(This article belongs to the Special Issue State-of-the-Art Sensors Technology in Spain)
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Article
Precise 3D Lug Pose Detection Sensor for Automatic Robot Welding Using a Structured-Light Vision System
Sensors 2009, 9(9), 7550-7565; https://doi.org/10.3390/s90907550 - 23 Sep 2009
Cited by 22 | Viewed by 8723
Abstract
In this study, we propose a precise 3D lug pose detection sensor for automatic robot welding of a lug to a huge steel plate used in shipbuilding, where the lug is a handle to carry the huge steel plate. The proposed sensor consists [...] Read more.
In this study, we propose a precise 3D lug pose detection sensor for automatic robot welding of a lug to a huge steel plate used in shipbuilding, where the lug is a handle to carry the huge steel plate. The proposed sensor consists of a camera and four laser line diodes, and its design parameters are determined by analyzing its detectable range and resolution. For the lug pose acquisition, four laser lines are projected on both lug and plate, and the projected lines are detected by the camera. For robust detection of the projected lines against the illumination change, the vertical threshold, thinning, Hough transform and separated Hough transform algorithms are successively applied to the camera image. The lug pose acquisition is carried out by two stages: the top view alignment and the side view alignment. The top view alignment is to detect the coarse lug pose relatively far from the lug, and the side view alignment is to detect the fine lug pose close to the lug. After the top view alignment, the robot is controlled to move close to the side of the lug for the side view alignment. By this way, the precise 3D lug pose can be obtained. Finally, experiments with the sensor prototype are carried out to verify the feasibility and effectiveness of the proposed sensor. Full article
(This article belongs to the Section Chemical Sensors)
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Article
Detecting Proteins in Highly Autofluorescent Cells Using Quantum Dot Antibody Conjugates
Sensors 2009, 9(9), 7540-7549; https://doi.org/10.3390/s90907540 - 23 Sep 2009
Cited by 10 | Viewed by 8925
Abstract
We have applied quantum dot (Qdot) antibody conjugates as a biomolecular probe for cellular proteins important in biogeochemical cycling in the sea. Conventional immunological methods have been hampered by the strong autofluorescence found in cyanobacteria cells. Qdot conjugates provide an ideal alternative for [...] Read more.
We have applied quantum dot (Qdot) antibody conjugates as a biomolecular probe for cellular proteins important in biogeochemical cycling in the sea. Conventional immunological methods have been hampered by the strong autofluorescence found in cyanobacteria cells. Qdot conjugates provide an ideal alternative for studies that require long-term imaging of cells such as detection of low abundance cellular antigens by fluorescence microscopy. The advantage of Qdot labeled probes over conventional immunological methods is the photostability of the probe. Phycoerythrin bleaches in cyanobacterial cells under prolonged UV or blue light excitation, which means that the semiconducting nanocrystal probe, the Qdot, can yield a strong fluorescent signal without interference from cellular pigments. Full article
(This article belongs to the Special Issue Nanotechnological Advances in Biosensors)
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Article
Remote-Sensing Image Classification Based on an Improved Probabilistic Neural Network
Sensors 2009, 9(9), 7516-7539; https://doi.org/10.3390/s90907516 - 23 Sep 2009
Cited by 58 | Viewed by 10567
Abstract
This paper proposes a hybrid classifier for polarimetric SAR images. The feature sets consist of span image, the H/A/α decomposition, and the GLCM-based texture features. Then, a probabilistic neural network (PNN) was adopted for classification, and a novel algorithm proposed to enhance its [...] Read more.
This paper proposes a hybrid classifier for polarimetric SAR images. The feature sets consist of span image, the H/A/α decomposition, and the GLCM-based texture features. Then, a probabilistic neural network (PNN) was adopted for classification, and a novel algorithm proposed to enhance its performance. Principle component analysis (PCA) was chosen to reduce feature dimensions, random division to reduce the number of neurons, and Brent’s search (BS) to find the optimal bias values. The results on San Francisco and Flevoland sites are compared to that using a 3-layer BPNN to demonstrate the validity of our algorithm in terms of confusion matrix and overall accuracy. In addition, the importance of each improvement of the algorithm was proven. Full article
(This article belongs to the Special Issue Neural Networks and Sensors)
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Article
A Wavelet Neural Network for SAR Image Segmentation
Sensors 2009, 9(9), 7509-7515; https://doi.org/10.3390/s90907509 - 22 Sep 2009
Cited by 6 | Viewed by 7836
Abstract
This paper proposes a wavelet neural network (WNN) for SAR image segmentation by combining the wavelet transform and an artificial neural network. The WNN combines the multiscale analysis ability of the wavelet transform and the classification capability of the artificial neural network by [...] Read more.
This paper proposes a wavelet neural network (WNN) for SAR image segmentation by combining the wavelet transform and an artificial neural network. The WNN combines the multiscale analysis ability of the wavelet transform and the classification capability of the artificial neural network by setting the wavelet function as the transfer function of the neural network. Several SAR images are segmented by the network whose transfer functions are the Morlet and Mexihat functions, respectively. The experimental results show the proposed method is very effective and accurate. Full article
(This article belongs to the Special Issue Neural Networks and Sensors)
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Article
Platform for a Hydrocarbon Exhaust Gas Sensor Utilizing a Pumping Cell and a Conductometric Sensor
Sensors 2009, 9(9), 7498-7508; https://doi.org/10.3390/s90907498 - 18 Sep 2009
Cited by 2 | Viewed by 8813
Abstract
Very often, high-temperature operated gas sensors are cross-sensitive to oxygen and/or they cannot be operated in oxygen-deficient (rich) atmospheres. For instance, some metal oxides like Ga2O3 or doped SrTiO3 are excellent materials for conductometric hydrocarbon detection in the rough [...] Read more.
Very often, high-temperature operated gas sensors are cross-sensitive to oxygen and/or they cannot be operated in oxygen-deficient (rich) atmospheres. For instance, some metal oxides like Ga2O3 or doped SrTiO3 are excellent materials for conductometric hydrocarbon detection in the rough atmosphere of automotive exhausts, but have to be operated preferably at a constant oxygen concentration. We propose a modular sensor platform that combines a conductometric two-sensor-setup with an electrochemical pumping cell made of YSZ to establish a constant oxygen concentration in the ambient of the conductometric sensor film. In this paper, the platform is introduced, the two-sensor-setup is integrated into this new design, and sensing performance is characterized. Such a platform can be used for other sensor principles as well. Full article
(This article belongs to the Special Issue Gas Sensors 2009)
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Article
Neuro-Genetic Optimization of the Diffuser Elements for Applications in a Valveless Diaphragm Micropumps System
Sensors 2009, 9(9), 7481-7497; https://doi.org/10.3390/s90907481 - 18 Sep 2009
Cited by 11 | Viewed by 8273
Abstract
In this study, a hybridized neuro-genetic optimization methodology realized by embedding numerical simulations trained artificial neural networks (ANN) into a genetic algorithm (GA) is used to optimize the flow rectification efficiency of the diffuser element for a valveless diaphragm micropump application. A higher [...] Read more.
In this study, a hybridized neuro-genetic optimization methodology realized by embedding numerical simulations trained artificial neural networks (ANN) into a genetic algorithm (GA) is used to optimize the flow rectification efficiency of the diffuser element for a valveless diaphragm micropump application. A higher efficiency ratio of the diffuser element consequently yields a higher flow rate for the micropump. For that purpose, optimization of the diffuser element is essential to determine the maximum pumping rate that the micropump is able to generate. Numerical simulations are initially carried out using CoventorWare® to analyze the effects of varying parameters such as diffuser angle, Reynolds number and aspect ratio on the volumetric flow rate of the micropump. A limited range of simulation results will then be used to train the neural network via back-propagation algorithm and optimization process commence subsequently by embedding the trained ANN results as a fitness function into GA. The objective of the optimization is to maximize the efficiency ratio of the diffuser element for the range of parameters investigated. The optimized efficiency ratio obtained from the neuro-genetic optimization is 1.38, which is higher than any of the maximum efficiency ratio attained from the overall parametric studies, establishing the superiority of the optimization method. Full article
(This article belongs to the Special Issue Neural Networks and Sensors)
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Review
The pH Response and Sensing Mechanism of n-Type ZnO/Electrolyte Interfaces
Sensors 2009, 9(9), 7445-7480; https://doi.org/10.3390/s90907445 - 16 Sep 2009
Cited by 72 | Viewed by 12156
Abstract
Ever since the discovery of the pH-sensing properties of ZnO crystals, researchers have been exploring their potential in electrochemical applications. The recent expansion and availability of chemical modification methods has made it possible to generate a new class of electrochemically active ZnO nanorods. [...] Read more.
Ever since the discovery of the pH-sensing properties of ZnO crystals, researchers have been exploring their potential in electrochemical applications. The recent expansion and availability of chemical modification methods has made it possible to generate a new class of electrochemically active ZnO nanorods. This reduction in size of ZnO (to a nanocrystalline form) using new growth techniques is essentially an example of the nanotechnology fabrication principle. The availability of these ZnO nanorods opens up an entire new and exciting research direction in the field of electrochemical sensing. This review covers the latest advances and mechanism of pH-sensing using ZnO nanorods, with an emphasis on the nano-interface mechanism. We discuss methods for calculating the effect of surface states on pH-sensing at a ZnO/electrolyte interface. All of these current research topics aim to explain the mechanism of pH-sensing using a ZnO bulk- or nano-scale single crystal. An important goal of these investigations is the translation of these nanotechnology-modified nanorods into potential novel applications. Full article
(This article belongs to the Special Issue Metal-Oxide Based Nanosensors)
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Article
A Capacitive Humidity Sensor Based on Multi-Wall Carbon Nanotubes (MWCNTs)
Sensors 2009, 9(9), 7431-7444; https://doi.org/10.3390/s90907431 - 16 Sep 2009
Cited by 100 | Viewed by 9655
Abstract
A new type of capacitive humidity sensor is introduced in this paper. The sensor consists of two plate electrodes coated with MWCNT films and four pieces of isolating medium at the four corners of the sensor. According to capillary condensation, the capacitance signal [...] Read more.
A new type of capacitive humidity sensor is introduced in this paper. The sensor consists of two plate electrodes coated with MWCNT films and four pieces of isolating medium at the four corners of the sensor. According to capillary condensation, the capacitance signal of the sensor is sensitive to relative humidity (RH), which could be transformed to voltage signal by a capacitance to voltage converter circuit. The sensor is tested using different saturated saline solutions at the ambient temperature of 25 °C, which yielded approximately 11% to 97% RH, respectively. The function of the MWCNT films, the effect of electrode distance, the temperature character and the repeatability of the sensor are discussed in this paper. Full article
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Correction
Correction: Ramos-Pérez, I. et al. Calibration of Correlation Radiometers Using Pseudo-Random Noise Signals. Sensors 2009, 9, 6131-6149
Sensors 2009, 9(9), 7430; https://doi.org/10.3390/s90907430 - 15 Sep 2009
Cited by 4 | Viewed by 8415
Abstract
It has come to our attention that in the original version of a paper published in Sensors recently, the names of four co-authors were misspelled with several hyphens missing. [...] Full article
Article
A Real-Time Smart Sensor for High-Resolution Frequency Estimation in Power Systems
Sensors 2009, 9(9), 7412-7429; https://doi.org/10.3390/s90907412 - 15 Sep 2009
Cited by 36 | Viewed by 9011
Abstract
Power quality monitoring is a theme in vogue and accurate frequency measurement of the power line is a major issue. This problem is particularly relevant for power generating systems since the generated signal must comply with restrictive standards. The novelty of this work [...] Read more.
Power quality monitoring is a theme in vogue and accurate frequency measurement of the power line is a major issue. This problem is particularly relevant for power generating systems since the generated signal must comply with restrictive standards. The novelty of this work is the development of a smart sensor for real-time high-resolution frequency measurement in accordance with international standards for power quality monitoring. The proposed smart sensor utilizes commercially available current clamp, hall-effect sensor or resistor as primary sensor. The signal processing is carried out through the chirp z-transform. Simulations and experimental results show the efficiency of the proposed smart sensor. Full article
(This article belongs to the Special Issue Sensor Configuration and Smart Sensors)
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Article
Chalcogenide Glass Optical Waveguides for Infrared Biosensing
Sensors 2009, 9(9), 7398-7411; https://doi.org/10.3390/s90907398 - 15 Sep 2009
Cited by 122 | Viewed by 11169
Abstract
Due to the remarkable properties of chalcogenide (Chg) glasses, Chg optical waveguides should play a significant role in the development of optical biosensors. This paper describes the fabrication and properties of chalcogenide fibres and planar waveguides. Using optical fibre transparent in the mid-infrared [...] Read more.
Due to the remarkable properties of chalcogenide (Chg) glasses, Chg optical waveguides should play a significant role in the development of optical biosensors. This paper describes the fabrication and properties of chalcogenide fibres and planar waveguides. Using optical fibre transparent in the mid-infrared spectral range we have developed a biosensor that can collect information on whole metabolism alterations, rapidly and in situ. Thanks to this sensor it is possible to collect infrared spectra by remote spectroscopy, by simple contact with the sample. In this way, we tried to determine spectral modifications due, on the one hand, to cerebral metabolism alterations caused by a transient focal ischemia in the rat brain and, in the other hand, starvation in the mouse liver. We also applied a microdialysis method, a well known technique for in vivo brain metabolism studies, as reference. In the field of integrated microsensors, reactive ion etching was used to pattern rib waveguides between 2 and 300 μm wide. This technique was used to fabricate Y optical junctions for optical interconnections on chalcogenide amorphous films, which can potentially increase the sensitivity and stability of an optical micro-sensor. The first tests were also carried out to functionalise the Chg planar waveguides with the aim of using them as (bio)sensors. Full article
(This article belongs to the Special Issue State-of-the-Art Sensors Technology in Japan)
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Correction
Correction: Stević, Z. et al. Estimation of Parameters Obtained by Electrochemical Impedance Spectroscopy on Systems Containing High Capacities. Sensors 2009, 9, 7365-7373
Sensors 2009, 9(9), 7397; https://doi.org/10.3390/s90907397 - 14 Sep 2009
Cited by 1 | Viewed by 7018
Abstract
In the original published version of this paper, the name and affiliation of the third coauthor was listed by mistake. [...] Full article
(This article belongs to the Section Chemical Sensors)
Article
Modelling and Calibration Technique of Laser Triangulation Sensors for Integration in Robot Arms and Articulated Arm Coordinate Measuring Machines
Sensors 2009, 9(9), 7374-7396; https://doi.org/10.3390/s90907374 - 11 Sep 2009
Cited by 46 | Viewed by 14078
Abstract
A technique for intrinsic and extrinsic calibration of a laser triangulation sensor (LTS) integrated in an articulated arm coordinate measuring machine (AACMM) is presented in this paper. After applying a novel approach to the AACMM kinematic parameter identification problem, by means of a [...] Read more.
A technique for intrinsic and extrinsic calibration of a laser triangulation sensor (LTS) integrated in an articulated arm coordinate measuring machine (AACMM) is presented in this paper. After applying a novel approach to the AACMM kinematic parameter identification problem, by means of a single calibration gauge object, a one-step calibration method to obtain both intrinsic―laser plane, CCD sensor and camera geometry―and extrinsic parameters related to the AACMM main frame has been developed. This allows the integration of LTS and AACMM mathematical models without the need of additional optimization methods after the prior sensor calibration, usually done in a coordinate measuring machine (CMM) before the assembly of the sensor in the arm. The experimental tests results for accuracy and repeatability show the suitable performance of this technique, resulting in a reliable, quick and friendly calibration method for the AACMM final user. The presented method is also valid for sensor integration in robot arms and CMMs. Full article
(This article belongs to the Special Issue State-of-the-Art Sensors Technology in Spain)
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Article
Estimation of Parameters Obtained by Electrochemical Impedance Spectroscopy on Systems Containing High Capacities
Sensors 2009, 9(9), 7365-7373; https://doi.org/10.3390/s90907365 - 11 Sep 2009
Cited by 14 | Viewed by 7192 | Correction
Abstract
Electrochemical systems with high capacities demand devices for electrochemical impedance spectroscopy (EIS) with ultra-low frequencies (in order of mHz), that are almost impossible to accomplish with analogue techniques, but this becomes possible by using a computer technique and accompanying digital equipment. Recently, an [...] Read more.
Electrochemical systems with high capacities demand devices for electrochemical impedance spectroscopy (EIS) with ultra-low frequencies (in order of mHz), that are almost impossible to accomplish with analogue techniques, but this becomes possible by using a computer technique and accompanying digital equipment. Recently, an original software and hardware for electrochemical measurements, intended for electrochemical systems exhibiting high capacities, such as supercapacitors, has been developed. One of the included methods is EIS. In this paper, the method of calculation of circuit parameters from an EIS curve is described. The results of testing on a physical model of an electrochemical system, constructed of known elements (including a 1.6 F capacitor) in a defined arrangement, proved the validity of the system and the method. Full article
(This article belongs to the Section Chemical Sensors)
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Review
Nanomaterial-Assisted Signal Enhancement of Hybridization for DNA Biosensors: A Review
Sensors 2009, 9(9), 7343-7364; https://doi.org/10.3390/s90907343 - 11 Sep 2009
Cited by 45 | Viewed by 11630
Abstract
Detection of DNA sequences has received broad attention due to its potential applications in a variety of fields. As sensitivity of DNA biosensors is determined by signal variation of hybridization events, the signal enhancement is of great significance for improving the sensitivity in [...] Read more.
Detection of DNA sequences has received broad attention due to its potential applications in a variety of fields. As sensitivity of DNA biosensors is determined by signal variation of hybridization events, the signal enhancement is of great significance for improving the sensitivity in DNA detection, which still remains a great challenge. Nanomaterials, which possess some unique chemical and physical properties caused by nanoscale effects, provide a new opportunity for developing novel nanomaterial-based signal-enhancers for DNA biosensors. In this review, recent progress concerning this field, including some newly-developed signal enhancement approaches using quantum-dots, carbon nanotubes and their composites reported by our group and other researchers are comprehensively summarized. Reports on signal enhancement of DNA biosensors by non-nanomaterials, such as enzymes and polymer reagents, are also reviewed for comparison. Furthermore, the prospects for developing DNA biosensors using nanomaterials as signal-enhancers in future are also indicated. Full article
(This article belongs to the Special Issue Nanotechnological Advances in Biosensors)
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Article
Power Conservation through Energy Efficient Routing in Wireless Sensor Networks
Sensors 2009, 9(9), 7320-7342; https://doi.org/10.3390/s90907320 - 11 Sep 2009
Cited by 88 | Viewed by 14256
Abstract
The power awareness issue is the primary concern within the domain of Wireless Sensor Networks (WSNs). Most power dissipation ocurrs during communication, thus routing protocols in WSNs mainly aim at power conservation. Moreover, a routing protocol should be scalable, so that its effectiveness [...] Read more.
The power awareness issue is the primary concern within the domain of Wireless Sensor Networks (WSNs). Most power dissipation ocurrs during communication, thus routing protocols in WSNs mainly aim at power conservation. Moreover, a routing protocol should be scalable, so that its effectiveness does not degrade as the network size increases. In response to these issues, this work describes the development of an efficient routing protocol, named SHPER (Scaling Hierarchical Power Efficient Routing). Full article
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Article
Hazardous Odor Recognition by CMAC Based Neural Networks
Sensors 2009, 9(9), 7308-7319; https://doi.org/10.3390/s90907308 - 11 Sep 2009
Cited by 10 | Viewed by 7352
Abstract
Electronic noses are being developed as systems for the automated detection and classification of odors, vapors, and gases. Artificial neural networks (ANNs) have been used to analyze complex data and to recognize patterns, and have shown promising results in recognition of volatile compounds [...] Read more.
Electronic noses are being developed as systems for the automated detection and classification of odors, vapors, and gases. Artificial neural networks (ANNs) have been used to analyze complex data and to recognize patterns, and have shown promising results in recognition of volatile compounds and odors in electronic nose applications. When an ANN is combined with a sensor array, the number of detectable chemicals is generally greater than the number of unique sensor types. The odor sensing system should be extended to new areas since its standard style where the output pattern from multiple sensors with partially overlapped specificity is recognized by a neural network or multivariate analysis. This paper describes the design, implementation and performance evaluations of the application developed for hazardous odor recognition using Cerebellar Model Articulation Controller (CMAC) based neural networks. Full article
(This article belongs to the Section Chemical Sensors)
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Article
A Hybrid Adaptive Routing Algorithm for Event-Driven Wireless Sensor Networks
Sensors 2009, 9(9), 7287-7307; https://doi.org/10.3390/s90907287 - 10 Sep 2009
Cited by 14 | Viewed by 9861
Abstract
Routing is a basic function in wireless sensor networks (WSNs). For these networks, routing algorithms depend on the characteristics of the applications and, consequently, there is no self-contained algorithm suitable for every case. In some scenarios, the network behavior (traffic load) may vary [...] Read more.
Routing is a basic function in wireless sensor networks (WSNs). For these networks, routing algorithms depend on the characteristics of the applications and, consequently, there is no self-contained algorithm suitable for every case. In some scenarios, the network behavior (traffic load) may vary a lot, such as an event-driven application, favoring different algorithms at different instants. This work presents a hybrid and adaptive algorithm for routing in WSNs, called Multi-MAF, that adapts its behavior autonomously in response to the variation of network conditions. In particular, the proposed algorithm applies both reactive and proactive strategies for routing infrastructure creation, and uses an event-detection estimation model to change between the strategies and save energy. To show the advantages of the proposed approach, it is evaluated through simulations. Comparisons with independent reactive and proactive algorithms show improvements on energy consumption. Full article
(This article belongs to the Special Issue Sensor Algorithms)
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Review
Semiconductor Quantum Dots in Chemical Sensors and Biosensors
Sensors 2009, 9(9), 7266-7286; https://doi.org/10.3390/s90907266 - 10 Sep 2009
Cited by 342 | Viewed by 16998
Abstract
Quantum dots are nanometre-scale semiconductor crystals with unique optical properties that are advantageous for the development of novel chemical sensors and biosensors. The surface chemistry of luminescent quantum dots has encouraged the development of multiple probes based on linked recognition molecules such as [...] Read more.
Quantum dots are nanometre-scale semiconductor crystals with unique optical properties that are advantageous for the development of novel chemical sensors and biosensors. The surface chemistry of luminescent quantum dots has encouraged the development of multiple probes based on linked recognition molecules such as peptides, nucleic acids or small-molecule ligands. This review overviews the design of sensitive and selective nanoprobes, ranging from the type of target molecules to the optical transduction scheme. Representative examples of quantum dot-based optical sensors from this fast-moving field have been selected and are discussed towards the most promising directions for future research. Full article
(This article belongs to the Special Issue Nanotechnological Advances in Biosensors)
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Article
Bistatic Radar Configuration for Soil Moisture Retrieval: Analysis of the Spatial Coverage
Sensors 2009, 9(9), 7250-7265; https://doi.org/10.3390/s90907250 - 10 Sep 2009
Cited by 11 | Viewed by 8658
Abstract
Some outcomes of a feasibility analysis of a spaceborne bistatic radar mission for soil moisture retrieval are presented in this paper. The study starts from the orbital design of the configuration suitable for soil moisture estimation identified in a previous study. This configuration [...] Read more.
Some outcomes of a feasibility analysis of a spaceborne bistatic radar mission for soil moisture retrieval are presented in this paper. The study starts from the orbital design of the configuration suitable for soil moisture estimation identified in a previous study. This configuration is refined according to the results of an analysis of the spatial resolution. The paper focuses on the assessment of the spatial coverage i.e., on the verification that an adequate overlap between the footprints of the antennas is ensured and on the duty cycle, that is the fraction of orbital period during which the bistatic data are acquired. A non-cooperating system is considered, in which the transmitter is the C-band Advanced Synthetic Aperture Radar aboard Envisat. The best performances in terms of duty cycle are achieved if the transmitter operates in Wide Swath Mode. The higher resolution Image Swath Modes that comply with the selected configuration have a duty cycle that is never less than 12% and can exceed 21%. When Envisat operates in Wide Swath Mode, the bistatic system covers a wide latitude range across the equator, while in some of the Image Swath Modes, the bistatic measurements, collected from the same orbit, cover mid-latitude areas. In the latter case, it might be possible to achieve full coverage in an Envisat orbit repeat cycle, while, for a very large latitude range such as that covered in Wide Swath Mode, bistatic acquisitions could be obtained over about 65% of the area. Full article
(This article belongs to the Special Issue Sensor Configuration and Smart Sensors)
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Article
Detection and Classification of Human Body Odor Using an Electronic Nose
Sensors 2009, 9(9), 7234-7249; https://doi.org/10.3390/s90907234 - 09 Sep 2009
Cited by 86 | Viewed by 15739
Abstract
An electronic nose (E-nose) has been designed and equipped with software that can detect and classify human armpit body odor. An array of metal oxide sensors was used for detecting volatile organic compounds. The measurement circuit employs a voltage divider resistor to measure [...] Read more.
An electronic nose (E-nose) has been designed and equipped with software that can detect and classify human armpit body odor. An array of metal oxide sensors was used for detecting volatile organic compounds. The measurement circuit employs a voltage divider resistor to measure the sensitivity of each sensor. This E-nose was controlled by in-house developed software through a portable USB data acquisition card with a principle component analysis (PCA) algorithm implemented for pattern recognition and classification. Because gas sensor sensitivity in the detection of armpit odor samples is affected by humidity, we propose a new method and algorithms combining hardware/software for the correction of the humidity noise. After the humidity correction, the E-nose showed the capability of detecting human body odor and distinguishing the body odors from two persons in a relative manner. The E-nose is still able to recognize people, even after application of deodorant. In conclusion, this is the first report of the application of an E-nose for armpit odor recognition. Full article
(This article belongs to the Special Issue Sensor Algorithms)
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Article
Sensing Landscape History with an Interactive Location Based Service
Sensors 2009, 9(9), 7217-7233; https://doi.org/10.3390/s90907217 - 09 Sep 2009
Cited by 5 | Viewed by 11119
Abstract
This paper introduces the STEAD approach for interpreting data acquired by a “human sensor”, who uses an informal interactive location-based service (iLBS) to sense cultural-historic facts and anecdotes of, and in the landscape. This user-generated data is collected outdoors and in situ. [...] Read more.
This paper introduces the STEAD approach for interpreting data acquired by a “human sensor”, who uses an informal interactive location-based service (iLBS) to sense cultural-historic facts and anecdotes of, and in the landscape. This user-generated data is collected outdoors and in situ. The approach consists of four related facets (who, what, where, when). Three of the four facets are discussed and illustrated by user generated data collected during a Dutch survey in 2008. These data represent the personal cultural-historic knowledge and anecdotes of 150 people using a customized iLBS for experiencing the cultural history of a landscape. The “who” facet shows three dominant mentality groups (cosmopolitans, modern materialists and post modern hedonists) that generated user content. The “what” facet focuses on three subject types of pictures and four picture framing classes. Pictures of the place type showed to be dominant and foreground framing class was slightly favourite. The “where” facet is explored via density, distribution, and distance of the pictures made. The illustrations of the facets indirectly show the role of the “human sensor” with respect to the domain of interest. The STEAD approach needs further development of the when-facet and of the relations between the four facets. Finally the results of the approach may support data archives of iLBS applications. Full article
(This article belongs to the Special Issue Workshop Sensing A Changing World)
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Article
Thick-Film Carbon Dioxide Sensor via Anodic Adsorbate Stripping Technique and Its Structural Dependence
Sensors 2009, 9(9), 7203-7216; https://doi.org/10.3390/s90907203 - 09 Sep 2009
Cited by 5 | Viewed by 7700
Abstract
A three-electrode based CO2 sensor was fabricated using thick-film technology. The performance of this sensor was further enhanced by incorporating platinum nanoparticles onto the working electrode surface. An eight-fold increase in the signal output was obtained from the electrode with the platinum [...] Read more.
A three-electrode based CO2 sensor was fabricated using thick-film technology. The performance of this sensor was further enhanced by incorporating platinum nanoparticles onto the working electrode surface. An eight-fold increase in the signal output was obtained from the electrode with the platinum nanoparticles. The sensing output was linearly related to the CO2 presented. Stability measurements demonstrated that the decline of the active surface area and the sensitivity of the sensor were 8% and 13%, respectively, over a two week period of time. The sensor response appeared to be a structural dependence of the crystallographic orientation of platinum electrode. Full article
(This article belongs to the Section Chemical Sensors)
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Article
Game and Balance Multicast Architecture Algorithms for Sensor Grid
Sensors 2009, 9(9), 7177-7202; https://doi.org/10.3390/s90907177 - 09 Sep 2009
Cited by 7 | Viewed by 8852
Abstract
We propose a scheme to attain shorter multicast delay and higher efficiency in the data transfer of sensor grid. Our scheme, in one cluster, seeks the central node, calculates the space and the data weight vectors. Then we try to find a new [...] Read more.
We propose a scheme to attain shorter multicast delay and higher efficiency in the data transfer of sensor grid. Our scheme, in one cluster, seeks the central node, calculates the space and the data weight vectors. Then we try to find a new vector composed by linear combination of the two old ones. We use the equal correlation coefficient between the new and old vectors to find the point of game and balance of the space and data factorsbuild a binary simple equation, seek linear parameters, and generate a least weight path tree. We handled the issue from a quantitative way instead of a qualitative way. Based on this idea, we considered the scheme from both the space and data factor, then we built the mathematic model, set up game and balance relationship and finally resolved the linear indexes, according to which we improved the transmission efficiency of sensor grid. Extended simulation results indicate that our scheme attains less average multicast delay and number of links used compared with other well-known existing schemes. Full article
(This article belongs to the Special Issue Sensor Algorithms)
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Article
Prediction of Force Measurements of a Microbend Sensor Based on an Artificial Neural Network
Sensors 2009, 9(9), 7167-7176; https://doi.org/10.3390/s90907167 - 09 Sep 2009
Cited by 24 | Viewed by 7007
Abstract
Artificial neural network (ANN) based prediction of the response of a microbend fiber optic sensor is presented. To the best of our knowledge no similar work has been previously reported in the literature. Parallel corrugated plates with three deformation cycles, 6 mm thickness [...] Read more.
Artificial neural network (ANN) based prediction of the response of a microbend fiber optic sensor is presented. To the best of our knowledge no similar work has been previously reported in the literature. Parallel corrugated plates with three deformation cycles, 6 mm thickness of the spacer material and 16 mm mechanical periodicity between deformations were used in the microbend sensor. Multilayer Perceptron (MLP) with different training algorithms, Radial Basis Function (RBF) network and General Regression Neural Network (GRNN) are used as ANN models in this work. All of these models can predict the sensor responses with considerable errors. RBF has the best performance with the smallest mean square error (MSE) values of training and test results. Among the MLP algorithms and GRNN the Levenberg-Marquardt algorithm has good results. These models successfully predict the sensor responses, hence ANNs can be used as useful tool in the design of more robust fiber optic sensors. Full article
(This article belongs to the Special Issue Neural Networks and Sensors)
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Article
A Non-Intrusive GMA Welding Process Quality Monitoring System Using Acoustic Sensing
Sensors 2009, 9(9), 7150-7166; https://doi.org/10.3390/s90907150 - 09 Sep 2009
Cited by 24 | Viewed by 8679
Abstract
Most of the inspection methods used for detection and localization of welding disturbances are based on the evaluation of some direct measurements of welding parameters. This direct measurement requires an insertion of sensors during the welding process which could somehow alter the behavior [...] Read more.
Most of the inspection methods used for detection and localization of welding disturbances are based on the evaluation of some direct measurements of welding parameters. This direct measurement requires an insertion of sensors during the welding process which could somehow alter the behavior of the metallic transference. An inspection method that evaluates the GMA welding process evolution using a non-intrusive process sensing would allow not only the identification of disturbances during welding runs and thus reduce inspection time, but would also reduce the interference on the process caused by the direct sensing. In this paper a nonintrusive method for weld disturbance detection and localization for weld quality evaluation is demonstrated. The system is based on the acoustic sensing of the welding electrical arc. During repetitive tests in welds without disturbances, the stability acoustic parameters were calculated and used as comparison references for the detection and location of disturbances during the weld runs. Full article
(This article belongs to the Section Chemical Sensors)
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Article
Image-Based Airborne Sensors: A Combined Approach for Spectral Signatures Classification through Deterministic Simulated Annealing
Sensors 2009, 9(9), 7132-7149; https://doi.org/10.3390/s90907132 - 08 Sep 2009
Cited by 4 | Viewed by 7901
Abstract
The increasing technology of high-resolution image airborne sensors, including those on board Unmanned Aerial Vehicles, demands automatic solutions for processing, either on-line or off-line, the huge amountds of image data sensed during the flights. The classification of natural spectral signatures in images is [...] Read more.
The increasing technology of high-resolution image airborne sensors, including those on board Unmanned Aerial Vehicles, demands automatic solutions for processing, either on-line or off-line, the huge amountds of image data sensed during the flights. The classification of natural spectral signatures in images is one potential application. The actual tendency in classification is oriented towards the combination of simple classifiers. In this paper we propose a combined strategy based on the Deterministic Simulated Annealing (DSA) framework. The simple classifiers used are the well tested supervised parametric Bayesian estimator and the Fuzzy Clustering. The DSA is an optimization approach, which minimizes an energy function. The main contribution of DSA is its ability to avoid local minima during the optimization process thanks to the annealing scheme. It outperforms simple classifiers used for the combination and some combined strategies, including a scheme based on the fuzzy cognitive maps and an optimization approach based on the Hopfield neural network paradigm. Full article
(This article belongs to the Special Issue Neural Networks and Sensors)
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Review
Ion-Sensitive Field-Effect Transistor for Biological Sensing
Sensors 2009, 9(9), 7111-7131; https://doi.org/10.3390/s90907111 - 07 Sep 2009
Cited by 306 | Viewed by 17481
Abstract
In recent years there has been great progress in applying FET-type biosensors for highly sensitive biological detection. Among them, the ISFET (ion-sensitive field-effect transistor) is one of the most intriguing approaches in electrical biosensing technology. Here, we review some of the main advances [...] Read more.
In recent years there has been great progress in applying FET-type biosensors for highly sensitive biological detection. Among them, the ISFET (ion-sensitive field-effect transistor) is one of the most intriguing approaches in electrical biosensing technology. Here, we review some of the main advances in this field over the past few years, explore its application prospects, and discuss the main issues, approaches, and challenges, with the aim of stimulating a broader interest in developing ISFET-based biosensors and extending their applications for reliable and sensitive analysis of various biomolecules such as DNA, proteins, enzymes, and cells. Full article
(This article belongs to the Special Issue ISFET Sensors)
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Review
Photocurable Polymers for Ion Selective Field Effect Transistors. 20 Years of Applications
Sensors 2009, 9(9), 7097-7110; https://doi.org/10.3390/s90907097 - 07 Sep 2009
Cited by 23 | Viewed by 10407
Abstract
Application of photocurable polymers for encapsulation of ion selective field effect transistors (ISFET) and for membrane formation in chemical sensitive field effect transistors (ChemFET) during the last 20 years is discussed. From a technological point of view these materials are quite interesting because [...] Read more.
Application of photocurable polymers for encapsulation of ion selective field effect transistors (ISFET) and for membrane formation in chemical sensitive field effect transistors (ChemFET) during the last 20 years is discussed. From a technological point of view these materials are quite interesting because they allow the use of standard photo-lithographic processes, which reduces significantly the time required for sensor encapsulation and membrane deposition and the amount of manual work required for this, all items of importance for sensor mass production. Problems associated with the application of this kind of polymers in sensors are analysed and estimation of future trends in this field of research are presented. Full article
(This article belongs to the Special Issue ISFET Sensors)
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