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Sensors, Volume 10, Issue 1 (January 2010), Pages 1-1011

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Open AccessArticle An Efficient Pipeline Wavefront Phase Recovery for the CAFADIS Camera for Extremely Large Telescopes
Sensors 2010, 10(1), 1-15; doi:10.3390/s100100001
Received: 30 November 2009 / Revised: 22 December 2009 / Accepted: 23 December 2009 / Published: 24 December 2009
Cited by 4 | PDF Full-text (310 KB) | HTML Full-text | XML Full-text
Abstract
In this paper we show a fast, specialized hardware implementation of the wavefront phase recovery algorithm using the CAFADIS camera. The CAFADIS camera is a new plenoptic sensor patented by the Universidad de La Laguna (Canary Islands, Spain): international patent PCT/ES2007/000046 (WIPO publication
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In this paper we show a fast, specialized hardware implementation of the wavefront phase recovery algorithm using the CAFADIS camera. The CAFADIS camera is a new plenoptic sensor patented by the Universidad de La Laguna (Canary Islands, Spain): international patent PCT/ES2007/000046 (WIPO publication number WO/2007/082975). It can simultaneously measure the wavefront phase and the distance to the light source in a real-time process. The pipeline algorithm is implemented using Field Programmable Gate Arrays (FPGA). These devices present architecture capable of handling the sensor output stream using a massively parallel approach and they are efficient enough to resolve several Adaptive Optics (AO) problems in Extremely Large Telescopes (ELTs) in terms of processing time requirements. The FPGA implementation of the wavefront phase recovery algorithm using the CAFADIS camera is based on the very fast computation of two dimensional fast Fourier Transforms (FFTs). Thus we have carried out a comparison between our very novel FPGA 2D-FFTa and other implementations. Full article
(This article belongs to the Special Issue State-of-the-Art Sensors Technology in Spain)
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Open AccessArticle Electronic Nose for Quality Control of Colombian Coffee through the Detection of Defects in “Cup Tests”
Sensors 2010, 10(1), 36-46; doi:10.3390/s100100036
Received: 30 October 2009 / Revised: 26 November 2009 / Accepted: 2 December 2009 / Published: 24 December 2009
Cited by 22 | PDF Full-text (748 KB) | HTML Full-text | XML Full-text
Abstract
Electronic noses (ENs), are used for many applications, but we must emphasize the importance of their application to foodstuffs like coffee. This paper presents a research study about the analysis of Colombian coffee samples for the detection and classification of defects (i.e.
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Electronic noses (ENs), are used for many applications, but we must emphasize the importance of their application to foodstuffs like coffee. This paper presents a research study about the analysis of Colombian coffee samples for the detection and classification of defects (i.e., using “Cup Tests”), which was conducted at the Almacafé quality control laboratory in Cúcuta, Colombia. The results obtained show that the application of an electronic nose called “A-NOSE”, may be used in the coffee industry for the cupping tests. The results show that e-nose technology can be a useful tool for quality control to evaluate the excellence of the Colombian coffee produced by National Federation of Coffee Growers. Full article
(This article belongs to the Section Chemical Sensors)
Open AccessArticle A Focusing Method in the Calibration Process of Image Sensors Based on IOFBs
Sensors 2010, 10(1), 47-60; doi:10.3390/s100100047
Received: 29 October 2009 / Revised: 14 November 2009 / Accepted: 27 November 2009 / Published: 24 December 2009
Cited by 3 | PDF Full-text (705 KB) | HTML Full-text | XML Full-text
Abstract
A focusing procedure in the calibration process of image sensors based on Incoherent Optical Fiber Bundles (IOFBs) is described using the information extracted from fibers. These procedures differ from any other currently known focusing method due to the non spatial in-out correspondence between
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A focusing procedure in the calibration process of image sensors based on Incoherent Optical Fiber Bundles (IOFBs) is described using the information extracted from fibers. These procedures differ from any other currently known focusing method due to the non spatial in-out correspondence between fibers, which produces a natural codification of the image to transmit. Focus measuring is essential prior to carrying out calibration in order to guarantee accurate processing and decoding. Four algorithms have been developed to estimate the focus measure; two methods based on mean grey level, and the other two based on variance. In this paper, a few simple focus measures are defined and compared. Some experimental results referred to the focus measure and the accuracy of the developed methods are discussed in order to demonstrate its effectiveness. Full article
(This article belongs to the Special Issue State-of-the-Art Sensors Technology in Spain)
Open AccessArticle RAC-Multi: Reader Anti-Collision Algorithm for Multichannel Mobile RFID Networks
Sensors 2010, 10(1), 84-96; doi:10.3390/s100100084
Received: 29 October 2009 / Revised: 1 December 2009 / Accepted: 4 December 2009 / Published: 24 December 2009
Cited by 11 | PDF Full-text (190 KB) | HTML Full-text | XML Full-text
Abstract
At present, RFID is installed on mobile devices such as mobile phones or PDAs and provides a means to obtain information about objects equipped with an RFID tag over a multi-channeled telecommunication networks. To use mobile RFIDs, reader collision problems should be addressed
[...] Read more.
At present, RFID is installed on mobile devices such as mobile phones or PDAs and provides a means to obtain information about objects equipped with an RFID tag over a multi-channeled telecommunication networks. To use mobile RFIDs, reader collision problems should be addressed given that readers are continuously moving. Moreover, in a multichannel environment for mobile RFIDs, interference between adjacent channels should be considered. This work first defines a new concept of a reader collision problem between adjacent channels and then suggests a novel reader anti-collision algorithm for RFID readers that use multiple channels. To avoid interference with adjacent channels, the suggested algorithm separates data channels into odd and even numbered channels and allocates odd-numbered channels first to readers. It also sets an unused channel between the control channel and data channels to ensure that control messages and the signal of the adjacent channel experience no interference. Experimental results show that suggested algorithm shows throughput improvements ranging from 29% to 46% for tag identifications compared to the GENTLE reader anti-collision algorithm for multichannel RFID networks. Full article
(This article belongs to the Section Chemical Sensors)
Open AccessArticle Tracking Control of Shape-Memory-Alloy Actuators Based on Self-Sensing Feedback and Inverse Hysteresis Compensation
Sensors 2010, 10(1), 112-127; doi:10.3390/s100100112
Received: 18 November 2009 / Revised: 15 December 2009 / Accepted: 16 December 2009 / Published: 28 December 2009
Cited by 29 | PDF Full-text (470 KB) | HTML Full-text | XML Full-text
Abstract
Shape memory alloys (SMAs) offer a high power-to-weight ratio, large recovery strain, and low driving voltages, and have thus attracted considerable research attention. The difficulty of controlling SMA actuators arises from their highly nonlinear hysteresis and temperature dependence. This paper describes a combination
[...] Read more.
Shape memory alloys (SMAs) offer a high power-to-weight ratio, large recovery strain, and low driving voltages, and have thus attracted considerable research attention. The difficulty of controlling SMA actuators arises from their highly nonlinear hysteresis and temperature dependence. This paper describes a combination of self-sensing and model-based control, where the model includes both the major and minor hysteresis loops as well as the thermodynamics effects. The self-sensing algorithm uses only the power width modulation (PWM) signal and requires no heavy equipment. The method can achieve high-accuracy servo control and is especially suitable for miniaturized applications. Full article
(This article belongs to the Special Issue Advances in Actuators)
Open AccessArticle Chip-Oriented Fluorimeter Design and Detection System Development for DNA Quantification in Nano-Liter Volumes
Sensors 2010, 10(1), 146-166; doi:10.3390/s100100146
Received: 23 November 2009 / Revised: 11 December 2009 / Accepted: 22 December 2009 / Published: 28 December 2009
Cited by 2 | PDF Full-text (850 KB) | HTML Full-text | XML Full-text
Abstract
The chip-based polymerase chain reaction (PCR) system has been developed in recent years to achieve DNA quantification. Using a microstructure and miniature chip, the volume consumption for a PCR can be reduced to a nano-liter. With high speed cycling and a low reaction
[...] Read more.
The chip-based polymerase chain reaction (PCR) system has been developed in recent years to achieve DNA quantification. Using a microstructure and miniature chip, the volume consumption for a PCR can be reduced to a nano-liter. With high speed cycling and a low reaction volume, the time consumption of one PCR cycle performed on a chip can be reduced. However, most of the presented prototypes employ commercial fluorimeters which are not optimized for fluorescence detection of such a small quantity sample. This limits the performance of DNA quantification, especially low experiment reproducibility. This study discusses the concept of a chip-oriented fluorimeter design. Using the analytical model, the current study analyzes the sensitivity and dynamic range of the fluorimeter to fit the requirements for detecting fluorescence in nano-liter volumes. Through the optimized processes, a real-time PCR on a chip system with only one nano-liter volume test sample is as sensitive as the commercial real-time PCR machine using the sample with twenty micro-liter volumes. The signal to noise (S/N) ratio of a chip system for DNA quantification with hepatitis B virus (HBV) plasmid samples is 3 dB higher. DNA quantification by the miniature chip shows higher reproducibility compared to the commercial machine with respect to samples of initial concentrations from 103 to 105 copies per reaction. Full article
(This article belongs to the Special Issue DNA Sensors and Biosensors)
Open AccessArticle 1-Hydroxypyrene–A Biochemical Marker for PAH Pollution Assessment of Aquatic Ecosystem
Sensors 2010, 10(1), 203-217; doi:10.3390/s100100203
Received: 4 December 2009 / Revised: 17 December 2009 / Accepted: 22 December 2009 / Published: 28 December 2009
Cited by 3 | PDF Full-text (423 KB) | HTML Full-text | XML Full-text
Abstract
The aim of the present study was to assess aquatic contamination by polycyclic aromatic hydrocarbons (PAH), using the 1-hydroxypyrene (1-OHP) content in fish bile as a biochemical marker. A total of 71 chub (Leuciscus cephalus L.) were collected from seven locations on the
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The aim of the present study was to assess aquatic contamination by polycyclic aromatic hydrocarbons (PAH), using the 1-hydroxypyrene (1-OHP) content in fish bile as a biochemical marker. A total of 71 chub (Leuciscus cephalus L.) were collected from seven locations on the Svitava and Svratka rivers in and around the industrial city of Brno, Czech Republic. The levels of 1-OHP were determined by reverse phase HPLC with fluorescence detection after deconjugation. Normalising the molar concentration of the biliary 1-OHP to the biliary protein content reduced sample variation. The content of 1-OHP was correlated with the PAH level in bottom sediment and semi-permeable membrane devices (SPMD), which was analyzed by a combination of HPLC/FLD and GC/MS methods. The highest mean values of 1-OHP were found in fish caught at the Svratka River at locations Modrice (169.2 ± 99.7 ng•mg-1 protein) and Rajhradice (152.2 ± 79.7 ng•mg-1 protein), which are located downstream from Brno. These values were significantly (P < 0.05) higher than those obtained from localities Knínicky (98.4 ± 66.1 ng•mg-1 protein) and Bílovice nad Svitavou (64.1 ± 31.4 ng•mg-1 protein). The lowest contents of PAH in sediment and SPMD were found at location Knínicky (1.5 mg•kg-1 dry mass and 19.4 ng•L-1, respectively). The highest contents of PAH in sediment and SPMD were found in Rajhradice (26.0 mg•kg-1 dry mass) and Svitava before junction (65.4 ng•L-1), respectively. A Spearman correlation test was applied to determine the relationship between biliary 1-OHP and the sum of PAH in sediment and SPMD. A positive, but no statistically significant correlation was found. The main impact sources of elevated level of PAHs in sites located downstream from Brno are most probably intensive industrial and agricultural activities and domestic waste. Full article
Open AccessArticle Design, Control and in Situ Visualization of Gas Nitriding Processes
Sensors 2010, 10(1), 218-240; doi:10.3390/s100100218
Received: 16 November 2009 / Revised: 15 December 2009 / Accepted: 20 December 2009 / Published: 28 December 2009
Cited by 7 | PDF Full-text (3620 KB) | HTML Full-text | XML Full-text
Abstract
The article presents a complex system of design, in situ visualization and control of the commonly used surface treatment process: the gas nitriding process. In the computer design conception, analytical mathematical models and artificial intelligence methods were used. As a result, possibilities were
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The article presents a complex system of design, in situ visualization and control of the commonly used surface treatment process: the gas nitriding process. In the computer design conception, analytical mathematical models and artificial intelligence methods were used. As a result, possibilities were obtained of the poly-optimization and poly-parametric simulations of the course of the process combined with a visualization of the value changes of the process parameters in the function of time, as well as possibilities to predict the properties of nitrided layers. For in situ visualization of the growth of the nitrided layer, computer procedures were developed which make use of the results of the correlations of direct and differential voltage and time runs of the process result sensor (magnetic sensor), with the proper layer growth stage. Computer procedures make it possible to combine, in the duration of the process, the registered voltage and time runs with the models of the process. Full article
(This article belongs to the Special Issue Sensor Algorithms)
Open AccessArticle A Multi-Fault Diagnosis Method for Sensor Systems Based on Principle Component Analysis
Sensors 2010, 10(1), 241-253; doi:10.3390/s100100241
Received: 10 October 2009 / Revised: 30 November 2009 / Accepted: 4 December 2009 / Published: 29 December 2009
Cited by 26 | PDF Full-text (436 KB) | HTML Full-text | XML Full-text
Abstract
A model based on PCA (principal component analysis) and a neural network is proposed for the multi-fault diagnosis of sensor systems. Firstly, predicted values of sensors are computed by using historical data measured under fault-free conditions and a PCA model. Secondly, the squared
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A model based on PCA (principal component analysis) and a neural network is proposed for the multi-fault diagnosis of sensor systems. Firstly, predicted values of sensors are computed by using historical data measured under fault-free conditions and a PCA model. Secondly, the squared prediction error (SPE) of the sensor system is calculated. A fault can then be detected when the SPE suddenly increases. If more than one sensor in the system is out of order, after combining different sensors and reconstructing the signals of combined sensors, the SPE is calculated to locate the faulty sensors. Finally, the feasibility and effectiveness of the proposed method is demonstrated by simulation and comparison studies, in which two sensors in the system are out of order at the same time. Full article
(This article belongs to the Section Chemical Sensors)
Open AccessArticle Spectroscopic and Chromatographic Characterization of Wastewater Organic Matter from a Biological Treatment Plant
Sensors 2010, 10(1), 254-265; doi:10.3390/s100100254
Received: 2 November 2009 / Revised: 27 November 2009 / Accepted: 23 December 2009 / Published: 29 December 2009
Cited by 10 | PDF Full-text (252 KB) | HTML Full-text | XML Full-text
Abstract
Spectroscopic and chromatographic changes in dissolved organic matter (DOM) characteristics of influent and treated sewage were investigated for a wastewater treatment plant (WWTP) with a biological advanced process. Refractory DOM (R-DOM) was defined as the dissolved organic carbon concentrations of the samples after
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Spectroscopic and chromatographic changes in dissolved organic matter (DOM) characteristics of influent and treated sewage were investigated for a wastewater treatment plant (WWTP) with a biological advanced process. Refractory DOM (R-DOM) was defined as the dissolved organic carbon concentrations of the samples after 28-day incubation for this study. Specific UV absorbance (SUVA), hydrophobicity, synchronous fluorescence spectra and molecular weight (MW) distributions were selected as DOM characteristics. The percent distribution of R-DOM for the effluent was much higher than that of the influent, indicating that biodegradable DOM was selectively removed during the process. Comparison of the influent versus the effluent sewage revealed that SUVA, fulvic-like fluorescence (FLF), humic-like fluorescence (HLF), the apparent MW values were enhanced during the treatment. This suggests that more aromatic and humic-like compounds were enriched during the biological process. No significant difference in the DOM characteristics was observed between the original effluent (i.e., prior to the incubation) and the influent sewage after the incubation. This result suggests that the major changes in wastewater DOM characteristics occurring during the biological advanced process were similar to those for simple microbial incubation. Full article
(This article belongs to the Section Chemical Sensors)
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Open AccessArticle Field Map Reconstruction in Magnetic Resonance Imaging Using Bayesian Estimation
Sensors 2010, 10(1), 266-279; doi:10.3390/s100100266
Received: 30 October 2009 / Revised: 24 December 2009 / Accepted: 25 December 2009 / Published: 30 December 2009
Cited by 19 | PDF Full-text (529 KB) | HTML Full-text | XML Full-text
Abstract
Field inhomogeneities in Magnetic Resonance Imaging (MRI) can cause blur or image distortion as they produce off-resonance frequency at each voxel. These effects can be corrected if an accurate field map is available. Field maps can be estimated starting from the phase of
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Field inhomogeneities in Magnetic Resonance Imaging (MRI) can cause blur or image distortion as they produce off-resonance frequency at each voxel. These effects can be corrected if an accurate field map is available. Field maps can be estimated starting from the phase of multiple complex MRI data sets. In this paper we present a technique based on statistical estimation in order to reconstruct a field map exploiting two or more scans. The proposed approach implements a Bayesian estimator in conjunction with the Graph Cuts optimization method. The effectiveness of the method has been proven on simulated and real data. Full article
(This article belongs to the Special Issue Image Sensors)
Open AccessArticle A Novel Biosensor for Evaluation of Apoptotic or Necrotic Effects of Nitrogen Dioxide during Acute Pancreatitis in Rat
Sensors 2010, 10(1), 280-291; doi:10.3390/s100100280
Received: 4 November 2009 / Revised: 30 November 2009 / Accepted: 23 December 2009 / Published: 30 December 2009
Cited by 8 | PDF Full-text (3091 KB) | HTML Full-text | XML Full-text
Abstract
The direct and accurate estimation of nitric dioxide levels is an extremely laborious and technically demanding procedure in the molecular diagnostics of inflammatory processes. The aim of this work is to demonstrate that a stop-flow technique utilizing a specific spectroscopic biosensor can be
[...] Read more.
The direct and accurate estimation of nitric dioxide levels is an extremely laborious and technically demanding procedure in the molecular diagnostics of inflammatory processes. The aim of this work is to demonstrate that a stop-flow technique utilizing a specific spectroscopic biosensor can be used for detection of nanomolar quantities of NO2 in biological milieu. The use of novel compound cis-[Cr(C2O4)(AaraNH2)(OH2)2]+ increases NO2 estimation accuracy by slowing down the rate of NO2 uptake. In this study, an animal model of pancreatitis, where nitrosative stress is induced by either 3g/kg bw or 1.5 g/kg bw dose of L-arginine, was used. Biochemical parameters and morphological characteristics of acute pancreatitis were monitored, specifically assessing pancreatic acinar cell death mode, NO2 generation and cellular glutathione level. The severity of the process correlated positively with NO2 levels in pancreatic acinar cell cytosol samples, and negatively with cellular glutathione levels. Full article
(This article belongs to the Section Biosensors)
Open AccessArticle PIYAS-Proceeding to Intelligent Service Oriented Memory Allocation for Flash Based Data Centric Sensor Devices in Wireless Sensor Networks
Sensors 2010, 10(1), 292-312; doi:10.3390/s100100292
Received: 11 November 2009 / Revised: 12 December 2009 / Accepted: 20 December 2009 / Published: 30 December 2009
Cited by 8 | PDF Full-text (427 KB) | HTML Full-text | XML Full-text
Abstract
Flash memory has become a more widespread storage medium for modern wireless devices because of its effective characteristics like non-volatility, small size, light weight, fast access speed, shock resistance, high reliability and low power consumption. Sensor nodes are highly resource constrained in terms
[...] Read more.
Flash memory has become a more widespread storage medium for modern wireless devices because of its effective characteristics like non-volatility, small size, light weight, fast access speed, shock resistance, high reliability and low power consumption. Sensor nodes are highly resource constrained in terms of limited processing speed, runtime memory, persistent storage, communication bandwidth and finite energy. Therefore, for wireless sensor networks supporting sense, store, merge and send schemes, an efficient and reliable file system is highly required with consideration of sensor node constraints. In this paper, we propose a novel log structured external NAND flash memory based file system, called Proceeding to Intelligent service oriented memorY Allocation for flash based data centric Sensor devices in wireless sensor networks (PIYAS). This is the extended version of our previously proposed PIYA [1]. The main goals of the PIYAS scheme are to achieve instant mounting and reduced SRAM space by keeping memory mapping information to a very low size of and to provide high query response throughput by allocation of memory to the sensor data by network business rules. The scheme intelligently samples and stores the raw data and provides high in-network data availability by keeping the aggregate data for a longer period of time than any other scheme has done before. We propose effective garbage collection and wear-leveling schemes as well. The experimental results show that PIYAS is an optimized memory management scheme allowing high performance for wireless sensor networks. Full article
Open AccessArticle Improving the Response of Accelerometers for Automotive Applications by Using LMS Adaptive Filters
Sensors 2010, 10(1), 313-329; doi:10.3390/s100100313
Received: 9 December 2009 / Revised: 29 December 2009 / Accepted: 30 December 2009 / Published: 31 December 2009
Cited by 9 | PDF Full-text (941 KB) | HTML Full-text | XML Full-text
Abstract
In this paper, the least-mean-squares (LMS) algorithm was used to eliminate noise corrupting the important information coming from a piezoresisitive accelerometer for automotive applications. This kind of accelerometer is designed to be easily mounted in hard to reach places on vehicles under test,
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In this paper, the least-mean-squares (LMS) algorithm was used to eliminate noise corrupting the important information coming from a piezoresisitive accelerometer for automotive applications. This kind of accelerometer is designed to be easily mounted in hard to reach places on vehicles under test, and they usually feature ranges from 50 to 2,000 g (where is the gravitational acceleration, 9.81 m/s2) and frequency responses to 3,000 Hz or higher, with DC response, durable cables, reliable performance and relatively low cost. However, here we show that the response of the sensor under test had a lot of noise and we carried out the signal processing stage by using both conventional and optimal adaptive filtering. Usually, designers have to build their specific analog and digital signal processing circuits, and this fact increases considerably the cost of the entire sensor system and the results are not always satisfactory, because the relevant signal is sometimes buried in a broad-band noise background where the unwanted information and the relevant signal sometimes share a very similar frequency band. Thus, in order to deal with this problem, here we used the LMS adaptive filtering algorithm and compare it with others based on the kind of filters that are typically used for automotive applications. The experimental results are satisfactory. Full article
Open AccessArticle An Evolution Based Biosensor Receptor DNA Sequence Generation Algorithm
Sensors 2010, 10(1), 330-341; doi:10.3390/s100100330
Received: 9 November 2009 / Revised: 30 November 2009 / Accepted: 21 December 2009 / Published: 31 December 2009
PDF Full-text (572 KB) | HTML Full-text | XML Full-text
Abstract
A biosensor is composed of a bioreceptor, an associated recognition molecule, and a signal transducer that can selectively detect target substances for analysis. DNA based biosensors utilize receptor molecules that allow hybridization with the target analyte. However, most DNA biosensor research uses oligonucleotides
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A biosensor is composed of a bioreceptor, an associated recognition molecule, and a signal transducer that can selectively detect target substances for analysis. DNA based biosensors utilize receptor molecules that allow hybridization with the target analyte. However, most DNA biosensor research uses oligonucleotides as the target analytes and does not address the potential problems of real samples. The identification of recognition molecules suitable for real target analyte samples is an important step towards further development of DNA biosensors. This study examines the characteristics of DNA used as bioreceptors and proposes a hybrid evolution-based DNA sequence generating algorithm, based on DNA computing, to identify suitable DNA bioreceptor recognition molecules for stable hybridization with real target substances. The Traveling Salesman Problem (TSP) approach is applied in the proposed algorithm to evaluate the safety and fitness of the generated DNA sequences. This approach improves efficiency and stability for enhanced and variable-length DNA sequence generation and allows extension to generation of variable-length DNA sequences with diverse receptor recognition requirements. Full article
(This article belongs to the Special Issue Microbial Sensors and Biosensors)
Open AccessArticle Infiltration Route Analysis Using Thermal Observation Devices (TOD) and Optimization Techniques in a GIS Environment
Sensors 2010, 10(1), 342-360; doi:10.3390/s100100342
Received: 17 December 2009 / Revised: 27 December 2009 / Accepted: 28 December 2009 / Published: 4 January 2010
Cited by 4 | PDF Full-text (1947 KB) | HTML Full-text | XML Full-text
Abstract
Infiltration-route analysis is a military application of geospatial information system (GIS) technology. In order to find susceptible routes, optimal-path-searching algorithms are applied to minimize the cost function, which is the summed result of detection probability. The cost function was determined according to the
[...] Read more.
Infiltration-route analysis is a military application of geospatial information system (GIS) technology. In order to find susceptible routes, optimal-path-searching algorithms are applied to minimize the cost function, which is the summed result of detection probability. The cost function was determined according to the thermal observation device (TOD) detection probability, the viewshed analysis results, and two feature layers extracted from the vector product interim terrain data. The detection probability is computed and recorded for an individual cell (50 m × 50 m), and the optimal infiltration routes are determined with A* algorithm by minimizing the summed costs on the routes from a start point to an end point. In the present study, in order to simulate the dynamic nature of a realworld problem, one thousand cost surfaces in the GIS environment were generated with randomly located TODs and randomly selected infiltration start points. Accordingly, one thousand sets of vulnerable routes for infiltration purposes could be found, which could be accumulated and presented as an infiltration vulnerability map. This application can be further utilized for both optimal infiltration routing and surveillance network design. Indeed, dynamic simulation in the GIS environment is considered to be a powerful and practical solution for optimization problems. A similar approach can be applied to the dynamic optimal routing for civil infrastructure, which requires consideration of terrain-related constraints and cost functions. Full article
(This article belongs to the Section Chemical Sensors)
Open AccessArticle Binary Fingerprints at Fluctuation-Enhanced Sensing
Sensors 2010, 10(1), 361-373; doi:10.3390/s100100361
Received: 8 December 2009 / Revised: 23 December 2009 / Accepted: 28 December 2009 / Published: 5 January 2010
Cited by 10 | PDF Full-text (437 KB) | HTML Full-text | XML Full-text
Abstract
We have developed a simple way to generate binary patterns based on spectral slopes in different frequency ranges at fluctuation-enhanced sensing. Such patterns can be considered as binary "fingerprints" of odors. The method has experimentally been demonstrated with a commercial semiconducting metal oxide
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We have developed a simple way to generate binary patterns based on spectral slopes in different frequency ranges at fluctuation-enhanced sensing. Such patterns can be considered as binary "fingerprints" of odors. The method has experimentally been demonstrated with a commercial semiconducting metal oxide (Taguchi) sensor exposed to bacterial odors (Escherichia coli and Anthrax-surrogate Bacillus subtilis) and processing their stochastic signals. With a single Taguchi sensor, the situations of empty chamber, tryptic soy agar (TSA) medium, or TSA with bacteria could be distinguished with 100% reproducibility. The bacterium numbers were in the range of 2.5 × 104-106. To illustrate the relevance for ultra-low power consumption, we show that this new type of signal processing and pattern recognition task can be implemented by a simple analog circuitry and a few logic gates with total power consumption in the microWatts range. Full article
(This article belongs to the Special Issue Metal-Oxide Based Nanosensors)
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Open AccessArticle Building Intelligent Communication Systems for Handicapped Aphasiacs
Sensors 2010, 10(1), 374-387; doi:10.3390/s100100374
Received: 12 November 2009 / Revised: 10 December 2009 / Accepted: 15 December 2009 / Published: 5 January 2010
PDF Full-text (390 KB) | HTML Full-text | XML Full-text
Abstract
This paper presents an intelligent system allowing handicapped aphasiacs to perform basic communication tasks. It has the following three key features: (1) A 6-sensor data glove measures the finger gestures of a patient in terms of the bending degrees of his fingers. (2)
[...] Read more.
This paper presents an intelligent system allowing handicapped aphasiacs to perform basic communication tasks. It has the following three key features: (1) A 6-sensor data glove measures the finger gestures of a patient in terms of the bending degrees of his fingers. (2) A finger language recognition subsystem recognizes language components from the finger gestures. It employs multiple regression analysis to automatically extract proper finger features so that the recognition model can be fast and correctly constructed by a radial basis function neural network. (3) A coordinate-indexed virtual keyboard allows the users to directly access the letters on the keyboard at a practical speed. The system serves as a viable tool for natural and affordable communication for handicapped aphasiacs through continuous finger language input. Full article
(This article belongs to the Section Chemical Sensors)
Open AccessArticle Characterization, Modeling and Design Parameters Identification of Silicon Carbide Junction Field Effect Transistor for Temperature Sensor Applications
Sensors 2010, 10(1), 388-399; doi:10.3390/s100100388
Received: 6 November 2009 / Revised: 30 November 2009 / Accepted: 21 December 2009 / Published: 5 January 2010
Cited by 8 | PDF Full-text (603 KB) | HTML Full-text | XML Full-text
Abstract
Sensor technology is moving towards wide-band-gap semiconductors providing high temperature capable devices. Indeed, the higher thermal conductivity of silicon carbide, (three times more than silicon), permits better heat dissipation and allows better cooling and temperature management. Though many temperature sensors have already been
[...] Read more.
Sensor technology is moving towards wide-band-gap semiconductors providing high temperature capable devices. Indeed, the higher thermal conductivity of silicon carbide, (three times more than silicon), permits better heat dissipation and allows better cooling and temperature management. Though many temperature sensors have already been published, little endeavours have been invested in the study of silicon carbide junction field effect devices (SiC-JFET) as a temperature sensor. SiC-JFETs devices are now mature enough and it is close to be commercialized. The use of its specific properties versus temperatures is the major focus of this paper. The SiC-JFETs output current-voltage characteristics are characterized at different temperatures. The saturation current and its on-resistance versus temperature are successfully extracted. It is demonstrated that these parameters are proportional to the absolute temperature. A physics-based model is also presented. Relationships between on-resistance and saturation current versus temperature are introduced. A comparative study between experimental data and simulation results is conducted. Important to note, the proposed model and the experimental results reflect a successful agreement as far as a temperature sensor is concerned. Full article
(This article belongs to the Section Chemical Sensors)
Open AccessArticle Collaborative Localization in Wireless Sensor Networks via Pattern Recognition in Radio Irregularity Using Omnidirectional Antennas
Sensors 2010, 10(1), 400-427; doi:10.3390/s100100400
Received: 27 October 2009 / Revised: 11 December 2009 / Accepted: 4 January 2010 / Published: 6 January 2010
Cited by 12 | PDF Full-text (888 KB) | HTML Full-text | XML Full-text
Abstract
In recent years, various received signal strength (RSS)-based localization estimation approaches for wireless sensor networks (WSNs) have been proposed. RSS-based localization is regarded as a low-cost solution for many location-aware applications in WSNs. In previous studies, the radiation patterns of all sensor nodes
[...] Read more.
In recent years, various received signal strength (RSS)-based localization estimation approaches for wireless sensor networks (WSNs) have been proposed. RSS-based localization is regarded as a low-cost solution for many location-aware applications in WSNs. In previous studies, the radiation patterns of all sensor nodes are assumed to be spherical, which is an oversimplification of the radio propagation model in practical applications. In this study, we present an RSS-based cooperative localization method that estimates unknown coordinates of sensor nodes in a network. Arrangement of two external low-cost omnidirectional dipole antennas is developed by using the distance-power gradient model. A modified robust regression is also proposed to determine the relative azimuth and distance between a sensor node and a fixed reference node. In addition, a cooperative localization scheme that incorporates estimations from multiple fixed reference nodes is presented to improve the accuracy of the localization. The proposed method is tested via computer-based analysis and field test. Experimental results demonstrate that the proposed low-cost method is a useful solution for localizing sensor nodes in unknown or changing environments. Full article
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Open AccessArticle Reliability Testing Procedure for MEMS IMUs Applied to Vibrating Environments
Sensors 2010, 10(1), 456-474; doi:10.3390/s100100456
Received: 10 December 2009 / Revised: 24 December 2009 / Accepted: 28 December 2009 / Published: 7 January 2010
Cited by 8 | PDF Full-text (1017 KB) | HTML Full-text | XML Full-text
Abstract
The diffusion of micro electro-mechanical systems (MEMS) technology applied to navigation systems is rapidly increasing, but currently, there is a lack of knowledge about the reliability of this typology of devices, representing a serious limitation to their use in aerospace vehicles and other
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The diffusion of micro electro-mechanical systems (MEMS) technology applied to navigation systems is rapidly increasing, but currently, there is a lack of knowledge about the reliability of this typology of devices, representing a serious limitation to their use in aerospace vehicles and other fields with medium and high requirements. In this paper, a reliability testing procedure for inertial sensors and inertial measurement units (IMU) based on MEMS for applications in vibrating environments is presented. The sensing performances were evaluated in terms of signal accuracy, systematic errors, and accidental errors; the actual working conditions were simulated by means of an accelerated dynamic excitation. A commercial MEMS-based IMU was analyzed to validate the proposed procedure. The main weaknesses of the system have been localized by providing important information about the relationship between the reliability levels of the system and individual components. Full article
(This article belongs to the Special Issue Modeling, Testing and Reliability Issues in MEMS Engineering - 2009)
Open AccessArticle Optimal Clinical Time for Reliable Measurement of Transcutaneous CO2 with Ear Probes: Counterbalancing Overshoot and the Vasodilatation Effect
Sensors 2010, 10(1), 491-500; doi:10.3390/s100100491
Received: 23 November 2009 / Revised: 20 December 2009 / Accepted: 21 December 2009 / Published: 11 January 2010
Cited by 1 | PDF Full-text (67 KB) | HTML Full-text | XML Full-text
Abstract
OBJECTIVES: To determine the optimal clinical reading time for the transcutaneous measurement of oxygen saturation (SpO) and transcutaneous CO2 (TcPCO2) in awake spontaneously breathing individuals, considering the overshoot phenomenon (transient overestimation of arterial PaCO2). EXPERIMENTAL SECTION: Observational
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OBJECTIVES: To determine the optimal clinical reading time for the transcutaneous measurement of oxygen saturation (SpO ) and transcutaneous CO2 (TcPCO2) in awake spontaneously breathing individuals, considering the overshoot phenomenon (transient overestimation of arterial PaCO2). EXPERIMENTAL SECTION: Observational study of 91 (75 men) individuals undergoing forced spirometry, measurement of SpO2 and TcPCO2 with the SenTec monitor every two minutes until minute 20 and arterial blood gas (ABG) analysis. Overshoot severity: (a) mild (0.1–1.9 mm Hg); (b) moderate (2–4.9 mm Hg); (c) severe: (>5 mm Hg). The mean difference was calculated for SpO2 and TcPCO2 and arterial values of PaCO2 and SpO2. The intraclass correlation coefficient (ICC) between monitor readings and blood values was calculated as a measure of agreement. RESULTS: The mean age was 63.1 ± 11.8 years. Spirometric values: FVC: 75.4 ± 6.2%; FEV1: 72.9 ± 23.9%; FEV1/FVC: 70 ± 15.5%. ABG: PaO2: 82.6 ± 13.2; PaCO2: 39.9.1 ± 4.8 mmHg; SaO2: 95.3 ± 4.4%. Overshoot analysis: overshoot was mild in 33 (36.3%) patients, moderate in 20 (22%) and severe in nine (10%); no overshoot was observed in 29 (31%) patients. The lowest mean differences between arterial blood gas and TcPCO2 was –0.57 mmHg at minute 10, although the highest ICC was obtained at minutes 12 and 14 (>0.8). The overshoot lost its influence after minute 12. For SpO2, measurements were reliable at minute 2. CONCLUSIONS: The optimal clinical reading measurement recommended for the ear lobe TcPCO2 measurement ranges between minute 12 and 14. The SpO2 measurement can be performed at minute 2. Full article
(This article belongs to the Section Chemical Sensors)
Open AccessArticle SBMAC: Smart Blocking MAC Mechanism for Variable UW-ASN (Underwater Acoustic Sensor Network) Environment
Sensors 2010, 10(1), 501-525; doi:10.3390/s100100501
Received: 10 November 2009 / Revised: 14 December 2009 / Accepted: 1 January 2010 / Published: 12 January 2010
Cited by 15 | PDF Full-text (626 KB) | HTML Full-text | XML Full-text
Abstract
In this paper, several MAC scheduling methods applicable to an underwater environment are proposed. Besides, a new marine communication system model was proposed to improve the reliability of the proposed SBMAC method. The scheme minimizes transmission of control frames except for data transmission
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In this paper, several MAC scheduling methods applicable to an underwater environment are proposed. Besides, a new marine communication system model was proposed to improve the reliability of the proposed SBMAC method. The scheme minimizes transmission of control frames except for data transmission and various transmission methods and ACK methods can be used together. Simulation models are set indices and analysis of the underwater environment is established to conduct reliable simulations. Consequently, the performance improvement of the proposed method is verified with respect to delay time, data transmission rate, memory utilization, energy efficiency, etc. Full article
(This article belongs to the Section Chemical Sensors)
Open AccessArticle Semiconductor Laser Multi-Spectral Sensing and Imaging
Sensors 2010, 10(1), 544-583; doi:10.3390/s100100544
Received: 23 November 2009 / Revised: 14 December 2009 / Accepted: 5 January 2010 / Published: 13 January 2010
Cited by 3 | PDF Full-text (2239 KB) | HTML Full-text | XML Full-text
Abstract
Multi-spectral laser imaging is a technique that can offer a combination of the laser capability of accurate spectral sensing with the desirable features of passive multispectral imaging. The technique can be used for detection, discrimination, and identification of objects by their spectral signature.
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Multi-spectral laser imaging is a technique that can offer a combination of the laser capability of accurate spectral sensing with the desirable features of passive multispectral imaging. The technique can be used for detection, discrimination, and identification of objects by their spectral signature. This article describes and reviews the development and evaluation of semiconductor multi-spectral laser imaging systems. Although the method is certainly not specific to any laser technology, the use of semiconductor lasers is significant with respect to practicality and affordability. More relevantly, semiconductor lasers have their own characteristics; they offer excellent wavelength diversity but usually with modest power. Thus, system design and engineering issues are analyzed for approaches and trade-offs that can make the best use of semiconductor laser capabilities in multispectral imaging. A few systems were developed and the technique was tested and evaluated on a variety of natural and man-made objects. It was shown capable of high spectral resolution imaging which, unlike non-imaging point sensing, allows detecting and discriminating objects of interest even without a priori spectroscopic knowledge of the targets. Examples include material and chemical discrimination. It was also shown capable of dealing with the complexity of interpreting diffuse scattered spectral images and produced results that could otherwise be ambiguous with conventional imaging. Examples with glucose and spectral imaging of drug pills were discussed. Lastly, the technique was shown with conventional laser spectroscopy such as wavelength modulation spectroscopy to image a gas (CO). These results suggest the versatility and power of multi-spectral laser imaging, which can be practical with the use of semiconductor lasers. Full article
(This article belongs to the Special Issue Laser Spectroscopy and Sensing)
Open AccessArticle ELBARA II, an L-Band Radiometer System for Soil Moisture Research
Sensors 2010, 10(1), 584-612; doi:10.3390/s100100584
Received: 18 November 2009 / Revised: 9 December 2009 / Accepted: 15 December 2009 / Published: 13 January 2010
Cited by 31 | PDF Full-text (1202 KB) | HTML Full-text | XML Full-text | Supplementary Files
Abstract
L-band (1–2 GHz) microwave radiometry is a remote sensing technique that can be used to monitor soil moisture, and is deployed in the Soil Moisture and Ocean Salinity (SMOS) Mission of the European Space Agency (ESA). Performing ground-based radiometer campaigns before launch, during
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L-band (1–2 GHz) microwave radiometry is a remote sensing technique that can be used to monitor soil moisture, and is deployed in the Soil Moisture and Ocean Salinity (SMOS) Mission of the European Space Agency (ESA). Performing ground-based radiometer campaigns before launch, during the commissioning phase and during the operative SMOS mission is important for validating the satellite data and for the further improvement of the radiative transfer models used in the soil-moisture retrieval algorithms. To address these needs, three identical L-band radiometer systems were ordered by ESA. They rely on the proven architecture of the ETH L-Band radiometer for soil moisture research (ELBARA) with major improvements in the microwave electronics, the internal calibration sources, the data acquisition, the user interface, and the mechanics. The purpose of this paper is to describe the design of the instruments and the main characteristics that are relevant for the user. Full article
(This article belongs to the Section Remote Sensors)
Open AccessArticle Formation of Zwitterionic Fullerodendron Using a New DBN-Focal Dendron
Sensors 2010, 10(1), 613-624; doi:10.3390/s100100613
Received: 16 November 2009 / Revised: 30 December 2009 / Accepted: 6 January 2009 / Published: 14 January 2010
PDF Full-text (328 KB) | HTML Full-text | XML Full-text
Abstract
A new poly(amidoamine) dendron having 1,5-diazabicyclo[4.3.0]non-5-ene (DBN) at the focal point was synthesized. Interestingly, formation of zwitterionic fullerodendrons (λmax = 930 nm for C60 and 795 nm for C70) were observed by Vis-NIR spectroscopy upon the reaction of C
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A new poly(amidoamine) dendron having 1,5-diazabicyclo[4.3.0]non-5-ene (DBN) at the focal point was synthesized. Interestingly, formation of zwitterionic fullerodendrons (λmax = 930 nm for C60 and 795 nm for C70) were observed by Vis-NIR spectroscopy upon the reaction of C60 or C70 with the DBN-focal dendron. In particular, the C70 anion was effectively stabilized by the site isolation effect of the dendritic wedge. The half-life of fullerodendron 12b having C70 anion at the focal point reaches 7,345 min, which is 20 times longer than that of complex between C60 and pristine DBN. Furthermore, in order to confirm the structure of the zwitterionic complex, fullerodendron 12a was reprecipitated from benzonitrile/1,2,4-trimethylbenzene, and was observed using IR spectroscopy and APPI-MS. Full article
(This article belongs to the Special Issue Dendritic Sensors: From Dendrimer Molecules to Dendritic Cells)
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Open AccessArticle A Disposable Organophosphorus Pesticides Enzyme Biosensor Based on Magnetic Composite Nano-Particles Modified Screen Printed Carbon Electrode
Sensors 2010, 10(1), 625-638; doi:10.3390/s100100625
Received: 8 December 2009 / Revised: 4 January 2009 / Accepted: 11 January 2009 / Published: 15 January 2010
Cited by 35 | PDF Full-text (760 KB) | HTML Full-text | XML Full-text
Abstract
A disposable organophosphorus pesticides (OPs) enzyme biosensor based on magnetic composite nanoparticle-modified screen printed carbon electrodes (SPCE) has been developed. Firstly, an acetylcholinesterase (AChE)-coated Fe3O4/Au (GMP) magnetic nanoparticulate (GMP-AChE) was synthesized. Then, GMP-AChE was absorbed on the surface of
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A disposable organophosphorus pesticides (OPs) enzyme biosensor based on magnetic composite nanoparticle-modified screen printed carbon electrodes (SPCE) has been developed. Firstly, an acetylcholinesterase (AChE)-coated Fe3O4/Au (GMP) magnetic nanoparticulate (GMP-AChE) was synthesized. Then, GMP-AChE was absorbed on the surface of a SPCE modified by carbon nanotubes (CNTs)/nano-ZrO2/prussian blue (PB)/Nafion (Nf) composite membrane by an external magnetic field. Thus, the biosensor (SPCE|CNTs/ZrO2/PB/Nf|GMP-AChE) for OPs was fabricated. The surface of the biosensor was characterized by scanning electron micrography (SEM) and X-ray fluorescence spectrometery (XRFS) and its electrochemical properties were studied by cyclic voltammetry (CV) and differential pulse voltammetry (DPV). The degree of inhibition (A%) of the AChE by OPs was determined by measuring the reduction current of the PB generated by the AChE-catalyzed hydrolysis of acetylthiocholine (ATCh). In pH = 7.5 KNO3 solution, the A was related linearly to the concentration of dimethoate in the range from 1.0 × 10-3–10 ng•mL-1 with a detection limit of 5.6 × 10-4 ng•mL-1. The recovery rates in Chinese cabbage exhibited a range of 88%–105%. The results were consistent with the standard gas chromatography (GC) method. Compared with other enzyme biosensors the proposed biosensor exhibited high sensitivity, good selectivity with disposable, low consumption of sample. In particular its surface can be easily renewed by removal of the magnet. The convenient, fast and sensitive voltammetric measurement opens new opportunities for OPs analysis. Full article
(This article belongs to the Section Biosensors)
Open AccessArticle An Innovative Procedure for Calibration of Strapdown Electro-Optical Sensors Onboard Unmanned Air Vehicles
Sensors 2010, 10(1), 639-654; doi:10.3390/s100100639
Received: 23 October 2009 / Revised: 7 December 2009 / Accepted: 18 December 2009 / Published: 18 January 2010
Cited by 16 | PDF Full-text (606 KB) | HTML Full-text | XML Full-text
Abstract
This paper presents an innovative method for estimating the attitude of airborne electro-optical cameras with respect to the onboard autonomous navigation unit. The procedure is based on the use of attitude measurements under static conditions taken by an inertial unit and carrier-phase differential
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This paper presents an innovative method for estimating the attitude of airborne electro-optical cameras with respect to the onboard autonomous navigation unit. The procedure is based on the use of attitude measurements under static conditions taken by an inertial unit and carrier-phase differential Global Positioning System to obtain accurate camera position estimates in the aircraft body reference frame, while image analysis allows line-of-sight unit vectors in the camera based reference frame to be computed. The method has been applied to the alignment of the visible and infrared cameras installed onboard the experimental aircraft of the Italian Aerospace Research Center and adopted for in-flight obstacle detection and collision avoidance. Results show an angular uncertainty on the order of 0.1° (rms). Full article
(This article belongs to the Section Remote Sensors)
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Open AccessArticle Label-Free Toxin Detection by Means of Time-Resolved Electrochemical Impedance Spectroscopy
Sensors 2010, 10(1), 655-669; doi:10.3390/s100100655
Received: 20 November 2009 / Revised: 7 December 2009 / Accepted: 10 December 2009 / Published: 18 January 2010
Cited by 13 | PDF Full-text (587 KB) | HTML Full-text | XML Full-text
Abstract
The real-time detection of trace concentrations of biological toxins requires significant improvement of the detection methods from those reported in the literature. To develop a highly sensitive and selective detection device it is necessary to determine the optimal measuring conditions for the electrochemical
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The real-time detection of trace concentrations of biological toxins requires significant improvement of the detection methods from those reported in the literature. To develop a highly sensitive and selective detection device it is necessary to determine the optimal measuring conditions for the electrochemical sensor in three domains: time, frequency and polarization potential. In this work we utilized a time-resolved electrochemical impedance spectroscopy for the detection of trace concentrations of Staphylococcus enterotoxin B (SEB). An anti-SEB antibody has been attached to the nano-porous aluminum surface using 3-aminopropyltriethoxysilane/glutaraldehyde coupling system. This immobilization method allows fabrication of a highly reproducible and stable sensing device. Using developed immobilization procedure and optimized detection regime, it is possible to determine the presence of SEB at the levels as low as 10 pg/mL in 15 minutes. Full article
(This article belongs to the Section Chemical Sensors)
Open AccessArticle A Macroporous TiO2 Oxygen Sensor Fabricated Using Anodic Aluminium Oxide as an Etching Mask
Sensors 2010, 10(1), 670-683; doi:10.3390/s100100670
Received: 10 December 2009 / Revised: 1 January 2010 / Accepted: 12 January 2010 / Published: 19 January 2010
Cited by 21 | PDF Full-text (807 KB) | HTML Full-text | XML Full-text
Abstract
An innovative fabrication method to produce a macroporous Si surface by employing an anodic aluminium oxide (AAO) nanopore array layer as an etching template is presented. Combining AAO with a reactive ion etching (RIE) processes, a homogeneous and macroporous silicon surface can be
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An innovative fabrication method to produce a macroporous Si surface by employing an anodic aluminium oxide (AAO) nanopore array layer as an etching template is presented. Combining AAO with a reactive ion etching (RIE) processes, a homogeneous and macroporous silicon surface can be effectively configured by modulating AAO process parameters and alumina film thickness, thus hopefully replacing conventional photolithography and electrochemical etch methods. The hybrid process integration is considered fully CMOS compatible thanks to the low-temperature AAO and CMOS processes. The gas-sensing characteristics of 50 nm TiO2 nanofilms deposited on the macroporous surface are compared with those of conventional plain (or non-porous) nanofilms to verify reduced response noise and improved sensitivity as a result of their macroporosity. Our experimental results reveal that macroporous geometry of the TiO2 chemoresistive gas sensor demonstrates 2-fold higher (~33%) improved sensitivity than a non-porous sensor at different levels of oxygen exposure. In addition, the macroporous device exhibits excellent discrimination capability and significantly lessened response noise at 500 °C. Experimental results indicate that the hybrid process of such miniature and macroporous devices are compatible as well as applicable to integrated next generation bio-chemical sensors. Full article
(This article belongs to the Special Issue Metal-Oxide Based Nanosensors)
Open AccessArticle Fast Fourier Transform IR Characterization of Epoxy GY Systems Crosslinked with Aliphatic and Cycloaliphatic EH Polyamine Adducts
Sensors 2010, 10(1), 684-696; doi:10.3390/s100100684
Received: 22 December 2009 / Revised: 12 January 2010 / Accepted: 18 January 2010 / Published: 19 January 2010
Cited by 67 | PDF Full-text (158 KB) | HTML Full-text | XML Full-text
Abstract
The use of fast FT-IR spectroscopy as a sensitive method to estimate a change of the crosslinking kinetics of epoxy resin with polyamine adducts is described in this study. A new epoxy formulation based on the use of polyamine adducts as the hardeners
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The use of fast FT-IR spectroscopy as a sensitive method to estimate a change of the crosslinking kinetics of epoxy resin with polyamine adducts is described in this study. A new epoxy formulation based on the use of polyamine adducts as the hardeners was analyzed. Crosslinking reactions of the different stoichiometric mixtures of the unmodified GY250 epoxy resin with the aliphatic EH606 and the cycloaliphatic EH637 polyamine adducts were studied using mid FT-IR spectroscopic techniques. As the crosslinking proceeded, the primary amine groups in polyamine adduct are converted to secondary and the tertiary amines. The decrease in the IR band intensity of epoxy groups at about 915 cm-1, as well as at about 3,056 cm-1, was observed due to process. Mid IR spectral analysis was used to calculate the content of the epoxy groups as a function of crosslinking time and the crosslinking degree of resin. The amount of all the epoxy species was estimated from IR spectra to changes during the crosslinking kinetics of epichlorhydrin. Full article
(This article belongs to the Section Chemical Sensors)
Open AccessArticle Real-time PCR Machine System Modeling and a Systematic Approach for the Robust Design of a Real-time PCR-on-a-Chip System
Sensors 2010, 10(1), 697-718; doi:10.3390/s100100697
Received: 7 December 2009 / Revised: 8 January 2010 / Accepted: 12 January 2010 / Published: 19 January 2010
Cited by 5 | PDF Full-text (1036 KB) | HTML Full-text | XML Full-text
Abstract
Chip-based DNA quantification systems are widespread, and used in many point-of-care applications. However, instruments for such applications may not be maintained or calibrated regularly. Since machine reliability is a key issue for normal operation, this study presents a system model of the real-time
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Chip-based DNA quantification systems are widespread, and used in many point-of-care applications. However, instruments for such applications may not be maintained or calibrated regularly. Since machine reliability is a key issue for normal operation, this study presents a system model of the real-time Polymerase Chain Reaction (PCR) machine to analyze the instrument design through numerical experiments. Based on model analysis, a systematic approach was developed to lower the variation of DNA quantification and achieve a robust design for a real-time PCR-on-a-chip system. Accelerated lift testing was adopted to evaluate the reliability of the chip prototype. According to the life test plan, this proposed real-time PCR-on-a-chip system was simulated to work continuously for over three years with similar reproducibility in DNA quantification. This not only shows the robustness of the lab-on-a-chip system, but also verifies the effectiveness of our systematic method for achieving a robust design. Full article
(This article belongs to the Special Issue DNA Sensors and Biosensors)
Open AccessArticle Deflection of Cross-Ply Composite Laminates Induced by Piezoelectric Actuators
Sensors 2010, 10(1), 719-733; doi:10.3390/s100100719
Received: 7 December 2009 / Revised: 4 January 2010 / Accepted: 18 January 2010 / Published: 20 January 2010
Cited by 6 | PDF Full-text (593 KB) | HTML Full-text | XML Full-text
Abstract
The coupling effects between the mechanical and electric properties of piezoelectric materials have drawn significant attention for their potential applications as sensors and actuators. In this investigation, two piezoelectric actuators are symmetrically surface bonded on a cross-ply composite laminate. Electric voltages with the
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The coupling effects between the mechanical and electric properties of piezoelectric materials have drawn significant attention for their potential applications as sensors and actuators. In this investigation, two piezoelectric actuators are symmetrically surface bonded on a cross-ply composite laminate. Electric voltages with the same amplitude and opposite sign are applied to the two symmetric piezoelectric actuators, resulting in the bending effect on the laminated plate. The bending moment is derived by using the classical laminate theory and piezoelectricity. The analytical solution of the flexural displacement of the simply supported composite plate subjected to the bending moment is solved by using the plate theory. The analytical solution is compared with the finite element solution to show the validation of present approach. The effects of the size and location of the piezoelectric actuators on the response of the composite laminate are presented through a parametric study. A simple model incorporating the classical laminate theory and plate theory is presented to predict the deformed shape of the simply supported laminate plate. Full article
(This article belongs to the Special Issue Advances in Actuators)
Open AccessArticle Evaluation of Oil-Palm Fungal Disease Infestation with Canopy Hyperspectral Reflectance Data
Sensors 2010, 10(1), 734-747; doi:10.3390/s100100734
Received: 18 November 2009 / Revised: 28 December 2009 / Accepted: 18 January 2010 / Published: 20 January 2010
Cited by 15 | PDF Full-text (785 KB) | HTML Full-text | XML Full-text
Abstract
Fungal disease detection in perennial crops is a major issue in estate management and production. However, nowadays such diagnostics are long and difficult when only made from visual symptom observation, and very expensive and damaging when based on root or stem tissue chemical
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Fungal disease detection in perennial crops is a major issue in estate management and production. However, nowadays such diagnostics are long and difficult when only made from visual symptom observation, and very expensive and damaging when based on root or stem tissue chemical analysis. As an alternative, we propose in this study to evaluate the potential of hyperspectral reflectance data to help detecting the disease efficiently without destruction of tissues. This study focuses on the calibration of a statistical model of discrimination between several stages of Ganoderma attack on oil palm trees, based on field hyperspectral measurements at tree scale. Field protocol and measurements are first described. Then, combinations of pre-processing, partial least square regression and linear discriminant analysis are tested on about hundred samples to prove the efficiency of canopy reflectance in providing information about the plant sanitary status. A robust algorithm is thus derived, allowing classifying oil-palm in a 4-level typology, based on disease severity from healthy to critically sick stages, with a global performance close to 94%. Moreover, this model discriminates sick from healthy trees with a confidence level of almost 98%. Applications and further improvements of this experiment are finally discussed. Full article
(This article belongs to the Section Remote Sensors)
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Open AccessArticle Development of an Alcohol Dehydrogenase Biosensor for Ethanol Determination with Toluidine Blue O Covalently Attached to a Cellulose Acetate Modified Electrode
Sensors 2010, 10(1), 748-764; doi:10.3390/s100100748
Received: 18 November 2009 / Revised: 29 December 2009 / Accepted: 12 January 2010 / Published: 21 January 2010
Cited by 19 | PDF Full-text (577 KB) | HTML Full-text | XML Full-text
Abstract
In this work, a novel voltammetric ethanol biosensor was constructed using alcohol dehydrogenase (ADH). Firstly, alcohol dehydrogenase was immobilized on the surface of a glassy carbon electrode modified by cellulose acetate (CA) bonded to toluidine blue O (TBO). Secondly, the surface was covered
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In this work, a novel voltammetric ethanol biosensor was constructed using alcohol dehydrogenase (ADH). Firstly, alcohol dehydrogenase was immobilized on the surface of a glassy carbon electrode modified by cellulose acetate (CA) bonded to toluidine blue O (TBO). Secondly, the surface was covered by a glutaraldehyde/bovine serum albumin (BSA) cross-linking procedure to provide a new voltammetric sensor for the ethanol determination. In order to fabricate the biosensor, a new electrode matrix containing insoluble Toluidine Blue O (TBO) was obtained from the process, and enzyme/coenzyme was combined on the biosensor surface. The influence of various experimental conditions was examined for the characterization of the optimum analytical performance. The developed biosensor exhibited sensitive and selective determination of ethanol and showed a linear response between 1 × 10−5 M and 4 × 10−4 M ethanol. A detection limit calculated as three times the signal-to-noise ratio was 5.0 × 10−6 M. At the end of the 20th day, the biosensor still retained 50% of its initial activity. Full article
(This article belongs to the Section Chemical Sensors)
Open AccessArticle A Nanopore Structured High Performance Toluene Gas Sensor Made by Nanoimprinting Method
Sensors 2010, 10(1), 765-774; doi:10.3390/s100100765
Received: 24 November 2009 / Revised: 16 December 2009 / Accepted: 5 January 2010 / Published: 21 January 2010
Cited by 19 | PDF Full-text (401 KB) | HTML Full-text | XML Full-text
Abstract
Toluene gas was successfully measured at room temperature using a device microfabricated by a nanoimprinting method. A highly uniform nanoporous thin film was produced with a dense array of titania (TiO2) pores with a diameter of 70~80 nm using this method.
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Toluene gas was successfully measured at room temperature using a device microfabricated by a nanoimprinting method. A highly uniform nanoporous thin film was produced with a dense array of titania (TiO2) pores with a diameter of 70~80 nm using this method. This thin film had a Pd/TiO2 nanoporous/SiO2/Si MIS layered structure with Pd-TiO2 as the catalytic sensing layer. The nanoimprinting method was useful in expanding the TiO2 surface area by about 30%, as confirmed using AFM and SEM imaging. The measured toluene concentrations ranged from 50 ppm to 200 ppm. The toluene was easily detected by changing the Pd/TiO2 interface work function, resulting in a change in the I-V characteristics. Full article
(This article belongs to the Special Issue Gas Sensors 2009)
Open AccessArticle The Non-linear Relationship between Muscle Voluntary Activation Level and Voluntary Force Measured by the Interpolated Twitch Technique
Sensors 2010, 10(1), 796-807; doi:10.3390/s100100796
Received: 4 December 2009 / Revised: 8 January 2010 / Accepted: 15 January 2010 / Published: 21 January 2010
Cited by 6 | PDF Full-text (258 KB) | HTML Full-text | XML Full-text
Abstract
Interpolated twitch technique (ITT) is a non-invasive method for assessing the completeness of muscle activation in clinical settings. Voluntary activation level (VA), measured by ITT and estimated by a conventional linear model, was reported to have a non-linear relationship with true voluntary contraction
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Interpolated twitch technique (ITT) is a non-invasive method for assessing the completeness of muscle activation in clinical settings. Voluntary activation level (VA), measured by ITT and estimated by a conventional linear model, was reported to have a non-linear relationship with true voluntary contraction force at higher activation levels. The relationship needs to be further clarified for the correct use by clinicians and researchers. This study was to established a modified voluntary activation (modified VA) and define a valid range by fitting a non-linear logistic growth model. Eight healthy male adults participated in this study. Each subject performed three sets of voluntary isometric ankle plantar flexions at 20, 40, 60, 80 and 100% maximal voluntary contraction (MVC) with real-time feedback on a computer screen. A supramaximal electrical stimulation was applied on tibia nerve at rest and during contractions. The estimated VA was calculated for each contraction. The relationship between the estimated VA and the actual voluntary contraction force was fitted by a logistic growth model. The result showed that according to the upper and lower limit points of the logistic curve, the valid range was between the 95.16% and 10.55% MVC. The modified VA estimated by this logistic growth model demonstrated less error than the conventional model. This study provided a transfer function for the voluntary activation level and defined the valid range which would provide useful information in clinical applications. Full article
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Open AccessArticle Effective Route Maintenance and Restoration Schemes in Mobile Ad Hoc Networks
Sensors 2010, 10(1), 808-821; doi:10.3390/s100100808
Received: 13 January 2010 / Revised: 18 January 2010 / Accepted: 20 January 2010 / Published: 21 January 2010
Cited by 9 | PDF Full-text (567 KB) | HTML Full-text | XML Full-text
Abstract
This study proposes a location-based hybrid routing protocol to improve data packet delivery and to reduce control message overhead in mobile ad hoc networks. In mobile environments, where nodes move continuously at a high speed, it is generally difficult to maintain and restore
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This study proposes a location-based hybrid routing protocol to improve data packet delivery and to reduce control message overhead in mobile ad hoc networks. In mobile environments, where nodes move continuously at a high speed, it is generally difficult to maintain and restore route paths. Therefore, this study suggests a new flooding mechanism to control route paths. The essence of the proposed scheme is its effective tracking of the destination’s location based on the beacon messages of the main route nodes. Through experiments based on an NS-2 simulator, the proposed scheme shows improvements in the data packet delivery ratio and reduces the amount of routing control message overhead compared with existing routing protocols such as AODV, LAR, ZRP and AODV-DFR. Full article
(This article belongs to the Section Chemical Sensors)
Open AccessArticle Intelligent Sensors Security
Sensors 2010, 10(1), 822-859; doi:10.3390/s100100822
Received: 16 December 2009 / Revised: 19 January 2010 / Accepted: 19 January 2010 / Published: 22 January 2010
Cited by 7 | PDF Full-text (778 KB) | HTML Full-text | XML Full-text
Abstract
The paper is focused on the security issues of sensors provided with processors and software and used for high-risk applications. Common IT related threats may cause serious consequences for sensor system users. To improve their robustness, sensor systems should be developed in a
[...] Read more.
The paper is focused on the security issues of sensors provided with processors and software and used for high-risk applications. Common IT related threats may cause serious consequences for sensor system users. To improve their robustness, sensor systems should be developed in a restricted way that would provide them with assurance. One assurance creation methodology is Common Criteria (ISO/IEC 15408) used for IT products and systems. The paper begins with a primer on the Common Criteria, and then a general security model of the intelligent sensor as an IT product is discussed. The paper presents how the security problem of the intelligent sensor is defined and solved. The contribution of the paper is to provide Common Criteria (CC) related security design patterns and to improve the effectiveness of the sensor development process. Full article
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Open AccessArticle Vision-Based Traffic Data Collection Sensor for Automotive Applications
Sensors 2010, 10(1), 860-875; doi:10.3390/s100100860
Received: 1 December 2009 / Revised: 19 January 2010 / Accepted: 20 January 2010 / Published: 22 January 2010
Cited by 10 | PDF Full-text (1260 KB) | HTML Full-text | XML Full-text
Abstract
This paper presents a complete vision sensor onboard a moving vehicle which collects the traffic data in its local area in daytime conditions. The sensor comprises a rear looking and a forward looking camera. Thus, a representative description of the traffic conditions in
[...] Read more.
This paper presents a complete vision sensor onboard a moving vehicle which collects the traffic data in its local area in daytime conditions. The sensor comprises a rear looking and a forward looking camera. Thus, a representative description of the traffic conditions in the local area of the host vehicle can be computed. The proposed sensor detects the number of vehicles (traffic load), their relative positions and their relative velocities in a four-stage process: lane detection, candidates selection, vehicles classification and tracking. Absolute velocities (average road speed) and global positioning are obtained after combining the outputs provided by the vision sensor with the data supplied by the CAN Bus and a GPS sensor. The presented experiments are promising in terms of detection performance and accuracy in order to be validated for applications in the context of the automotive industry. Full article
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Open AccessArticle Fluorescence-based Sensing of 2,4,6-Trinitrotoluene (TNT) Using a Multi-channeled Poly(methyl methacrylate) (PMMA) Microimmunosensor
Sensors 2010, 10(1), 876-889; doi:10.3390/s100100876
Received: 31 December 2009 / Revised: 15 January 2010 / Accepted: 19 January 2010 / Published: 22 January 2010
Cited by 18 | PDF Full-text (344 KB) | HTML Full-text | XML Full-text
Abstract
Fluorescence immunoassays employing monoclonal antibodies directed against the explosive 2,4,6-trinitrotoluene (TNT) were conducted in a multi-channel microimmunosensor. The multi-channel microimmunosensor was prepared in poly (methyl methacrylate) (PMMA) via hot embossing from a brass molding tool. The multi-channeled microfluidic device was sol-gel coated to
[...] Read more.
Fluorescence immunoassays employing monoclonal antibodies directed against the explosive 2,4,6-trinitrotoluene (TNT) were conducted in a multi-channel microimmunosensor. The multi-channel microimmunosensor was prepared in poly (methyl methacrylate) (PMMA) via hot embossing from a brass molding tool. The multi-channeled microfluidic device was sol-gel coated to generate a siloxane surface that provided a scaffold for antibody immobilization. AlexaFluor-cadaverine-trinitrobenzene (AlexaFluor-Cad-TNB) was used as the reporter molecule in a displacement immunoassay. The limit of detection was 1-10 ng/mL (ppb) with a linear dynamic range that covered three orders of magnitude. In addition, antibody crossreactivity was investigated using hexahydro-1,3,5-triazine (RDX), HMX, 2,4-dinitrotoluene (DNT), 4-nitrotoluene (4-NT) and 2-amino-4,6-DNT. Full article
(This article belongs to the Special Issue Fluorescent Chemosensors)
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Open AccessArticle Pterins as Sensors of Response to the Application of Fe3+-Dextran in Piglets
Sensors 2010, 10(1), 890-900; doi:10.3390/s100100890
Received: 16 November 2009 / Revised: 30 December 2009 / Accepted: 14 January 2010 / Published: 22 January 2010
Cited by 8 | PDF Full-text (156 KB) | HTML Full-text | XML Full-text
Abstract
The aim of the presented study was to assess the effect of a single administration of Fe3+-dextran on immune cell counts and pterin biomolecule production as novel sensors of the piglets' immune system activation, and to determine concentrations of cortisol, a
[...] Read more.
The aim of the presented study was to assess the effect of a single administration of Fe3+-dextran on immune cell counts and pterin biomolecule production as novel sensors of the piglets' immune system activation, and to determine concentrations of cortisol, a traditional hormonal biosensor of the stress response. Pterins (neopterin and biopterin) in the piglets' blood serum were analyzed by separation using reversed-phase HPLC. A single dose of Fe3+-dextran produced a special stress situation in the piglets' organism which manifested itself by an increased production of neopterin (p < 0.05) and biopterin (p < 0.01) in the experimental piglets. Changes in cortisol concentrations and leukocyte counts were influenced by handling stress and were not specifically correlated to iron dextran application. Iron concentrations in the internal environment of the experimental piglets’ group were higher by an order of magnitude compared with the controls, and the highest serum concentrations of iron (p < 0.01) were reached 24 h following Fe3+-dextran administration. The data presented offer a new perspective on the evaluation of stress situations in the animal organism and, not least importantly, extends the rather modest current list of references on the role of pterins in livestock animals. Full article
Open AccessArticle Microencapsulation of Flavors in Carnauba Wax
Sensors 2010, 10(1), 901-912; doi:10.3390/s100100901
Received: 29 October 2009 / Revised: 1 December 2009 / Accepted: 25 December 2009 / Published: 25 January 2010
Cited by 18 | PDF Full-text (429 KB) | HTML Full-text | XML Full-text
Abstract
The subject of this study is the development of flavor wax formulations aimed for food and feed products. The melt dispersion technique was applied for the encapsulation of ethyl vanillin in wax microcapsules. The surface morphology of microparticles was investigated using scanning electron
[...] Read more.
The subject of this study is the development of flavor wax formulations aimed for food and feed products. The melt dispersion technique was applied for the encapsulation of ethyl vanillin in wax microcapsules. The surface morphology of microparticles was investigated using scanning electron microscope (SEM), while the loading content was determined by HPLC measurements. This study shows that the decomposition process under heating proceeds in several steps: vanilla evaporation occurs at around 200 °C, while matrix degradation starts at 250 °C and progresses with maxima at around 360, 440 and 520 °C. The results indicate that carnauba wax is an attractive material for use as a matrix for encapsulation of flavours in order to improve their functionality and stability in products. Full article
(This article belongs to the Section Chemical Sensors)
Open AccessArticle Analysis of Large Scale Spatial Variability of Soil Moisture Using a Geostatistical Method
Sensors 2010, 10(1), 913-932; doi:10.3390/s100100913
Received: 28 December 2009 / Revised: 11 January 2010 / Accepted: 19 January 2010 / Published: 25 January 2010
Cited by 16 | PDF Full-text (484 KB) | HTML Full-text | XML Full-text
Abstract
Spatial and temporal soil moisture dynamics are critically needed to improve the parameterization for hydrological and meteorological modeling processes. This study evaluates the statistical spatial structure of large-scale observed and simulated estimates of soil moisture under pre- and post-precipitation event conditions. This large
[...] Read more.
Spatial and temporal soil moisture dynamics are critically needed to improve the parameterization for hydrological and meteorological modeling processes. This study evaluates the statistical spatial structure of large-scale observed and simulated estimates of soil moisture under pre- and post-precipitation event conditions. This large scale variability is a crucial in calibration and validation of large-scale satellite based data assimilation systems. Spatial analysis using geostatistical approaches was used to validate modeled soil moisture by the Agriculture Meteorological (AGRMET) model using in situ measurements of soil moisture from a state-wide environmental monitoring network (Oklahoma Mesonet). The results show that AGRMET data produces larger spatial decorrelation compared to in situ based soil moisture data. The precipitation storms drive the soil moisture spatial structures at large scale, found smaller decorrelation length after precipitation. This study also evaluates the geostatistical approach for mitigation for quality control issues within in situ soil moisture network to estimates at soil moisture at unsampled stations. Full article
(This article belongs to the Section Remote Sensors)
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Open AccessArticle A Device for Automatically Measuring and Supervising the Critical Care Patient’S Urine Output
Sensors 2010, 10(1), 934-951; doi:10.3390/s100100934
Received: 14 December 2009 / Revised: 15 January 2010 / Accepted: 18 January 2010 / Published: 26 January 2010
Cited by 8 | PDF Full-text (713 KB) | HTML Full-text | XML Full-text
Abstract
Critical care units are equipped with commercial monitoring devices capable of sensing patients’ physiological parameters and supervising the achievement of the established therapeutic goals. This avoids human errors in this task and considerably decreases the workload of the healthcare staff. However, at present
[...] Read more.
Critical care units are equipped with commercial monitoring devices capable of sensing patients’ physiological parameters and supervising the achievement of the established therapeutic goals. This avoids human errors in this task and considerably decreases the workload of the healthcare staff. However, at present there still is a very relevant physiological parameter that is measured and supervised manually by the critical care units’ healthcare staff: urine output. This paper presents a patent-pending device capable of automatically recording and supervising the urine output of a critical care patient. A high precision scale is used to measure the weight of a commercial urine meter. On the scale’s pan there is a support frame made up of Bosch profiles that isolates the scale from force transmission from the patient’s bed, and guarantees that the urine flows properly through the urine meter input tube. The scale’s readings are sent to a PC via Bluetooth where an application supervises the achievement of the therapeutic goals. The device is currently undergoing tests at a research unit associated with the University Hospital of Getafe in Spain. Full article
(This article belongs to the Special Issue State-of-the-Art Sensors Technology in Spain)
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Open AccessArticle Improving the Response of Accelerometers for Automotive Applications by Using LMS Adaptive Filters: Part II
Sensors 2010, 10(1), 952-962; doi:10.3390/s100100952
Received: 22 December 2009 / Revised: 15 January 2010 / Accepted: 25 January 2010 / Published: 26 January 2010
Cited by 3 | PDF Full-text (1381 KB) | HTML Full-text | XML Full-text
Abstract
In this paper, the fast least-mean-squares (LMS) algorithm was used to both eliminate noise corrupting the important information coming from a piezoresisitive accelerometer for automotive applications, and improve the convergence rate of the filtering process based on the conventional LMS algorithm. The response
[...] Read more.
In this paper, the fast least-mean-squares (LMS) algorithm was used to both eliminate noise corrupting the important information coming from a piezoresisitive accelerometer for automotive applications, and improve the convergence rate of the filtering process based on the conventional LMS algorithm. The response of the accelerometer under test was corrupted by process and measurement noise, and the signal processing stage was carried out by using both conventional filtering, which was already shown in a previous paper, and optimal adaptive filtering. The adaptive filtering process relied on the LMS adaptive filtering family, which has shown to have very good convergence and robustness properties, and here a comparative analysis between the results of the application of the conventional LMS algorithm and the fast LMS algorithm to solve a real-life filtering problem was carried out. In short, in this paper the piezoresistive accelerometer was tested for a multi-frequency acceleration excitation. Due to the kind of test conducted in this paper, the use of conventional filtering was discarded and the choice of one adaptive filter over the other was based on the signal-to-noise ratio improvement and the convergence rate. Full article
Open AccessArticle A Novel Bioinspired PVDF Micro/Nano Hair Receptor for a Robot Sensing System
Sensors 2010, 10(1), 994-1011; doi:10.3390/s100100994
Received: 1 December 2009 / Revised: 15 December 2009 / Accepted: 11 January 2010 / Published: 26 January 2010
Cited by 18 | PDF Full-text (828 KB) | HTML Full-text | XML Full-text
Abstract
This paper describes the concept and design of a novel artificial hair receptor for the sensing system of micro intelligent robots such as a cricket-like jumping mini robot. The concept is inspired from the natural hair receptor of animals, also called cilium or
[...] Read more.
This paper describes the concept and design of a novel artificial hair receptor for the sensing system of micro intelligent robots such as a cricket-like jumping mini robot. The concept is inspired from the natural hair receptor of animals, also called cilium or filiform hair by different research groups, which is usually used as a vibration receptor or a flow detector by insects, mammals and fishes. The suspended fiber model is firstly built and the influence of scaling down is analyzed theoretically. The design of this artificial hair receptor is based on aligned suspended PVDF (polyvinylidene fluoride) fibers, manufactures with a novel method called thermo-direct drawing technique, and aligned suspended submicron diameter fibers are thus successfully fabricated on a flexible Kapton. In the post process step, some key problems such as separated electrodes deposition along with the fiber drawing direction and poling of micro/nano fibers to impart them with good piezoeffective activity have been presented. The preliminary validation experiments show that the artificial hair receptor has a reliable response with good sensibility to external pressure variation and, medium flow as well as its prospects in the application on sensing system of mini/micro bio-robots. Full article
(This article belongs to the Special Issue Advances in Actuators)

Review

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Open AccessReview Toward 100 Mega-Frames per Second: Design of an Ultimate Ultra-High-Speed Image Sensor
Sensors 2010, 10(1), 16-35; doi:10.3390/s100100016
Received: 3 November 2009 / Revised: 3 December 2009 / Accepted: 8 December 2009 / Published: 24 December 2009
Cited by 19 | PDF Full-text (4509 KB) | HTML Full-text | XML Full-text
Abstract
Our experiencein the design of an ultra-high speed image sensor targeting the theoretical maximum frame rate is summarized. The imager is the backside illuminated in situ storage image sensor (BSI ISIS). It is confirmed that the critical factor limiting the highest frame rate
[...] Read more.
Our experiencein the design of an ultra-high speed image sensor targeting the theoretical maximum frame rate is summarized. The imager is the backside illuminated in situ storage image sensor (BSI ISIS). It is confirmed that the critical factor limiting the highest frame rate is the signal electron transit time from the generation layer at the back side of each pixel to the input gate to the in situ storage area on the front side. The theoretical maximum frame rate is estimated at 100 Mega-frames per second (Mfps) by transient simulation study. The sensor has a spatial resolution of 140,800 pixels with 126 linear storage elements installed in each pixel. The very high sensitivity is ensured by application of backside illumination technology and cooling. The ultra-high frame rate is achieved by the in situ storage image sensor (ISIS) structure on the front side. In this paper, we summarize technologies developed to achieve the theoretical maximum frame rate, including: (1) a special p-well design by triple injections to generate a smooth electric field backside towards the collection gate on the front side, resulting in much shorter electron transit time; (2) design technique to reduce RC delay by employing an extra metal layer exclusively to electrodes responsible for ultra-high speed image capturing; (3) a CCD specific complementary on-chip inductance minimization technique with a couple of stacked differential bus lines. Full article
(This article belongs to the Special Issue Image Sensors)
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Open AccessReview ISFET Based Microsensors for Environmental Monitoring
Sensors 2010, 10(1), 61-83; doi:10.3390/s100100061
Received: 6 November 2009 / Revised: 3 December 2009 / Accepted: 4 December 2009 / Published: 24 December 2009
Cited by 60 | PDF Full-text (388 KB) | HTML Full-text | XML Full-text
Abstract
The use of microsensors for in-field monitoring of environmental parameters is gaining interest due to their advantages over conventional sensors. Among them microsensors based on semiconductor technology offer additional advantages such as small size, robustness, low output impedance and rapid response. Besides, the
[...] Read more.
The use of microsensors for in-field monitoring of environmental parameters is gaining interest due to their advantages over conventional sensors. Among them microsensors based on semiconductor technology offer additional advantages such as small size, robustness, low output impedance and rapid response. Besides, the technology used allows integration of circuitry and multiple sensors in the same substrate and accordingly they can be implemented in compact probes for particular applications e.g., in situ monitoring and/or on-line measurements. In the field of microsensors for environmental applications, Ion Selective Field Effect Transistors (ISFETs) have a special interest. They are particularly helpful for measuring pH and other ions in small volumes and they can be integrated in compact flow cells for continuous measurements. In this paper the technologies used to fabricate ISFETs and a review of the role of ISFETs in the environmental field are presented. Full article
(This article belongs to the Special Issue ISFET Sensors)
Open AccessReview The Inflammasome in Host Defense
Sensors 2010, 10(1), 97-111; doi:10.3390/s100100097
Received: 2 December 2009 / Revised: 17 December 2009 / Accepted: 18 December 2009 / Published: 28 December 2009
Cited by 9 | PDF Full-text (719 KB) | HTML Full-text | XML Full-text
Abstract
Nod-like receptors have emerged as an important family of sensors in host defense. These receptors are expressed in macrophages, dendritic cells and monocytes and play an important role in microbial immunity. Some Nod-like receptors form the inflammasome, a protein complex that activates caspase-1
[...] Read more.
Nod-like receptors have emerged as an important family of sensors in host defense. These receptors are expressed in macrophages, dendritic cells and monocytes and play an important role in microbial immunity. Some Nod-like receptors form the inflammasome, a protein complex that activates caspase-1 in response to several stimuli. Caspase-1 activation leads to processing and secretion of pro-inflammatory cytokines such as interleukin (IL)-1β and IL-18. Here, we discuss recent advances in the inflammasome field with an emphasis on host defense. We also compare differential requirements for inflammasome activation in dendritic cells, macrophages and monocytes. Full article
(This article belongs to the Special Issue Dendritic Sensors: From Dendrimer Molecules to Dendritic Cells)
Open AccessReview A Study of MAC Protocols for WBANs
Sensors 2010, 10(1), 128-145; doi:10.3390/s100100128
Received: 26 November 2009 / Revised: 7 December 2009 / Accepted: 20 December 2009 / Published: 28 December 2009
Cited by 48 | PDF Full-text (358 KB) | HTML Full-text | XML Full-text
Abstract
The seamless integration of low-power, miniaturised, invasive/non-invasive lightweight sensor nodes have contributed to the development of a proactive and unobtrusive Wireless Body Area Network (WBAN). A WBAN provides long-term health monitoring of a patient without any constraint on his/her normal dailylife activities. This
[...] Read more.
The seamless integration of low-power, miniaturised, invasive/non-invasive lightweight sensor nodes have contributed to the development of a proactive and unobtrusive Wireless Body Area Network (WBAN). A WBAN provides long-term health monitoring of a patient without any constraint on his/her normal dailylife activities. This monitoring requires the low-power operation of invasive/non-invasive sensor nodes. In other words, a power-efficient Medium Access Control (MAC) protocol is required to satisfy the stringent WBAN requirements, including low-power consumption. In this paper, we first outline the WBAN requirements that are important for the design of a low-power MAC protocol. Then we study low-power MAC protocols proposed/investigated for a WBAN with emphasis on their strengths and weaknesses. We also review different power-efficient mechanisms for a WBAN. In addition, useful suggestions are given to help the MAC designers to develop a low-power MAC protocol that will satisfy the stringent requirements. Full article
(This article belongs to the Section Chemical Sensors)
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Open AccessReview Recent Advances in Sensing Oropharyngeal Swallowing Function in Japan
Sensors 2010, 10(1), 176-202; doi:10.3390/s100100176
Received: 1 November 2009 / Revised: 30 November 2009 / Accepted: 11 December 2009 / Published: 28 December 2009
Cited by 11 | PDF Full-text (3556 KB) | HTML Full-text | XML Full-text
Abstract
Dysphagia (difficulty in swallowing) is an important issue in the elderly because it causes aspiration pneumonia, which is the second largest cause of death in this group. It also causes decline in activities of daily living and quality of life. The oral phase
[...] Read more.
Dysphagia (difficulty in swallowing) is an important issue in the elderly because it causes aspiration pneumonia, which is the second largest cause of death in this group. It also causes decline in activities of daily living and quality of life. The oral phase of swallowing has been neglected, despite its importance in the evaluation of dysphagia, because adequate protocols and measuring devices are unavailable. However, recent advances in sensor technology have enabled straightforward, non-invasive measurement of the movement of important swallowing-related organs such as the lips and tongue, as well as the larynx. In this article, we report the present state and possibility of clinical application of such systems developed in Japan. Full article
(This article belongs to the Special Issue State-of-the-Art Sensors Technology in Japan)
Open AccessReview Nanotechnology for Early Cancer Detection
Sensors 2010, 10(1), 428-455; doi:10.3390/s100100428
Received: 10 November 2009 / Revised: 14 December 2009 / Accepted: 29 December 2009 / Published: 6 January 2010
Cited by 90 | PDF Full-text (3131 KB) | HTML Full-text | XML Full-text
Abstract
Vast numbers of studies and developments in the nanotechnology area have been conducted and many nanomaterials have been utilized to detect cancers at early stages. Nanomaterials have unique physical, optical and electrical properties that have proven to be very useful in sensing. Quantum
[...] Read more.
Vast numbers of studies and developments in the nanotechnology area have been conducted and many nanomaterials have been utilized to detect cancers at early stages. Nanomaterials have unique physical, optical and electrical properties that have proven to be very useful in sensing. Quantum dots, gold nanoparticles, magnetic nanoparticles, carbon nanotubes, gold nanowires and many other materials have been developed over the years, alongside the discovery of a wide range of biomarkers to lower the detection limit of cancer biomarkers. Proteins, antibody fragments, DNA fragments, and RNA fragments are the base of cancer biomarkers and have been used as targets in cancer detection and monitoring. It is highly anticipated that in the near future, we might be able to detect cancer at a very early stage, providing a much higher chance of treatment. Full article
(This article belongs to the Special Issue DNA Based Sensors)
Open AccessReview Ultramicroelectrode Array Based Sensors: A Promising Analytical Tool for Environmental Monitoring
Sensors 2010, 10(1), 475-490; doi:10.3390/s100100475
Received: 4 December 2009 / Revised: 16 December 2009 / Accepted: 24 December 2009 / Published: 7 January 2010
Cited by 20 | PDF Full-text (780 KB) | HTML Full-text | XML Full-text
Abstract
The particular analytical performance of ultramicroelectrode arrays (UMEAs) has attracted a high interest by the research community and has led to the development of a variety of electroanalytical applications. UMEA-based approaches have demonstrated to be powerful, simple, rapid and cost-effective analytical tools for
[...] Read more.
The particular analytical performance of ultramicroelectrode arrays (UMEAs) has attracted a high interest by the research community and has led to the development of a variety of electroanalytical applications. UMEA-based approaches have demonstrated to be powerful, simple, rapid and cost-effective analytical tools for environmental analysis compared to available conventional electrodes and standardised analytical techniques. An overview of the fabrication processes of UMEAs, their characterization and applications carried out by the Spanish scientific community is presented. A brief explanation of theoretical aspects that highlight their electrochemical behavior is also given. Finally, the applications of this transducer platform in the environmental field are discussed. Full article
(This article belongs to the Special Issue State-of-the-Art Sensors Technology in Spain)
Open AccessReview Nano-Bio-Technology and Sensing Chips: New Systems for Detection in Personalized Therapies and Cell Biology
Sensors 2010, 10(1), 526-543; doi:10.3390/s100100526
Received: 24 November 2009 / Revised: 30 December 2009 / Accepted: 5 January 2010 / Published: 12 January 2010
Cited by 23 | PDF Full-text (525 KB) | HTML Full-text | XML Full-text
Abstract
Further advances in molecular medicine and cell biology also require new electrochemical systems to detect disease biomarkers and therapeutic compounds. Microelectronic technology offers powerful circuits and systems to develop innovative and miniaturized biochips for sensing at the molecular level. However, microelectronic biochips proposed
[...] Read more.
Further advances in molecular medicine and cell biology also require new electrochemical systems to detect disease biomarkers and therapeutic compounds. Microelectronic technology offers powerful circuits and systems to develop innovative and miniaturized biochips for sensing at the molecular level. However, microelectronic biochips proposed in the literature often do not show the right specificity, sensitivity, and reliability required by biomedical applications. Nanotechnology offers new materials and solutions to improve the surface properties of sensing probes. The aim of the present paper is to review the most recent progress in Nano-Bio-Technology in the area of the development of new electrochemical systems for molecular detection in personalized therapy and cell culture monitoring. Full article
(This article belongs to the Special Issue Delft Workshop 2008-2009—Sensors and Imagers: a VLSI Perspective)
Open AccessReview Statistical Modeling of SAR Images: A Survey
Sensors 2010, 10(1), 775-795; doi:10.3390/s100100775
Received: 23 November 2009 / Revised: 5 January 2010 / Accepted: 6 January 2010 / Published: 21 January 2010
Cited by 73 | PDF Full-text (288 KB) | HTML Full-text | XML Full-text
Abstract
Statistical modeling is essential to SAR (Synthetic Aperture Radar) image interpretation. It aims to describe SAR images through statistical methods and reveal the characteristics of these images. Moreover, statistical modeling can provide a technical support for a comprehensive understanding of terrain scattering mechanism,
[...] Read more.
Statistical modeling is essential to SAR (Synthetic Aperture Radar) image interpretation. It aims to describe SAR images through statistical methods and reveal the characteristics of these images. Moreover, statistical modeling can provide a technical support for a comprehensive understanding of terrain scattering mechanism, which helps to develop algorithms for effective image interpretation and creditable image simulation. Numerous statistical models have been developed to describe SAR image data, and the purpose of this paper is to categorize and evaluate these models. We first summarize the development history and the current researching state of statistical modeling, then different SAR image models developed from the product model are mainly discussed in detail. Relevant issues are also discussed. Several promising directions for future research are concluded at last. Full article
Open AccessReview Nanomaterials as Analytical Tools for Genosensors
Sensors 2010, 10(1), 963-993; doi:10.3390/s100100963
Received: 12 December 2009 / Revised: 8 January 2010 / Accepted: 11 January 2010 / Published: 26 January 2010
Cited by 37 | PDF Full-text (361 KB) | HTML Full-text | XML Full-text
Abstract
Nanomaterials are being increasingly used for the development of electrochemical DNA biosensors, due to the unique electrocatalytic properties found in nanoscale materials. They offer excellent prospects for interfacing biological recognition events with electronic signal transduction and for designing a new generation of bioelectronic
[...] Read more.
Nanomaterials are being increasingly used for the development of electrochemical DNA biosensors, due to the unique electrocatalytic properties found in nanoscale materials. They offer excellent prospects for interfacing biological recognition events with electronic signal transduction and for designing a new generation of bioelectronic devices exhibiting novel functions. In particular, nanomaterials such as noble metal nanoparticles (Au, Pt), carbon nanotubes (CNTs), magnetic nanoparticles, quantum dots and metal oxide nanoparticles have been actively investigated for their applications in DNA biosensors, which have become a new interdisciplinary frontier between biological detection and material science. In this article, we address some of the main advances in this field over the past few years, discussing the issues and challenges with the aim of stimulating a broader interest in developing nanomaterial-based biosensors and improving their applications in disease diagnosis and food safety examination. Full article
(This article belongs to the Special Issue DNA Sensors and Biosensors)

Other

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Open AccessTechnical Note Microfabrication of Microchannels for Fuel Cell Plates
Sensors 2010, 10(1), 167-175; doi:10.3390/s100100167
Received: 21 October 2009 / Revised: 14 December 2009 / Accepted: 22 December 2009 / Published: 28 December 2009
Cited by 12 | PDF Full-text (290 KB) | HTML Full-text | XML Full-text
Abstract
Portable electronic devices such as notebook computers, PDAs, cellular phones, etc., are being widely used, and they increasingly need cheap, efficient, and lightweight power sources. Fuel cells have been proposed as possible power sources to address issues that involve energy production and
[...] Read more.
Portable electronic devices such as notebook computers, PDAs, cellular phones, etc., are being widely used, and they increasingly need cheap, efficient, and lightweight power sources. Fuel cells have been proposed as possible power sources to address issues that involve energy production and the environment. In particular, a small type of fuel-cell system is known to be suitable for portable electronic devices. The development of micro fuel cell systems can be achieved by the application of microchannel technology. In this study, the conventional method of chemical etching and the mechanical machining method of micro end milling were used for the microfabrication of microchannel for fuel cell separators. The two methods were compared in terms of their performance in the fabrication with regards to dimensional errors, flatness, straightness, and surface roughness. Following microchannel fabrication, the powder blasting technique is introduced to improve the coating performance of the catalyst on the surface of the microchannel. Experimental results show that end milling can remarkably increase the fabrication performance and that surface treatment by powder blasting can improve the performance of catalyst coating. Full article
(This article belongs to the Special Issue Modeling, Testing and Reliability Issues in MEMS Engineering - 2009)
Open AccessCorrection Correction: Dong, J. et al. Integrated Evaluation of Urban Development Suitability Based on Remote Sensing and GIS Techniques–A Case Study in Jingjinji Area, China. Sensors 2008, 8, 5975–5986
Sensors 2010, 10(1), 933; doi:10.3390/s100100933
Received: 25 January 2010 / Accepted: 25 January 2010 / Published: 25 January 2010
PDF Full-text (27 KB) | HTML Full-text | XML Full-text
Abstract We found that formula (1) was incorrect in our paper published in Sensors in 2008 [1]. [...] Full article

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