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Sensors, Volume 8, Issue 9 (September 2008), Pages 5229-6124

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Open AccessArticle Diagnosis of Intoxication by the Organophosphate VX: Comparison Between an Electrochemical Sensor and Ellman´s Photometric Method
Sensors 2008, 8(9), 5229-5237; doi:10.3390/s8095229
Received: 22 July 2008 / Revised: 27 August 2008 / Accepted: 28 August 2008 / Published: 1 September 2008
Cited by 20 | PDF Full-text (92 KB) | HTML Full-text | XML Full-text
Abstract
An electrochemical sensor is introduced as a tool applicable for diagnosis of intoxication by cholinesterase inhibitors caused by the well-known nerve agent VX. The traditional Ellman method was chosen for comparison with the sensor's analytical parameters. Both methods are based on estimation [...] Read more.
An electrochemical sensor is introduced as a tool applicable for diagnosis of intoxication by cholinesterase inhibitors caused by the well-known nerve agent VX. The traditional Ellman method was chosen for comparison with the sensor's analytical parameters. Both methods are based on estimation of blood cholinesterase inhibition as a marker of intoxication. While Ellman´s method provided a limit of detection of 5.2´10-7 M for blood containing VX, the electrochemical sensor was able to detect 4.0´10-7 M. Good correlation between both methods was observed (R = 0.92). The electrochemical sensor could be considered a convenient tool for a fast yet accurate method, easily available for field as well as laboratory use. Time and cost savings are key features of the sensor-based assay. Full article
Open AccessArticle Retrieval Algorithms for Road Surface Modelling Using Laser-Based Mobile Mapping
Sensors 2008, 8(9), 5238-5249; doi:10.3390/s8095238
Received: 11 July 2008 / Revised: 26 August 2008 / Accepted: 27 August 2008 / Published: 1 September 2008
Cited by 77 | PDF Full-text (573 KB) | HTML Full-text | XML Full-text
Abstract
Automated processing of the data provided by a laser-based mobile mapping system will be a necessity due to the huge amount of data produced. In the future, vehiclebased laser scanning, here called mobile mapping, should see considerable use for road environment modelling. [...] Read more.
Automated processing of the data provided by a laser-based mobile mapping system will be a necessity due to the huge amount of data produced. In the future, vehiclebased laser scanning, here called mobile mapping, should see considerable use for road environment modelling. Since the geometry of the scanning and point density is different from airborne laser scanning, new algorithms are needed for information extraction. In this paper, we propose automatic methods for classifying the road marking and kerbstone points and modelling the road surface as a triangulated irregular network. On the basis of experimental tests, the mean classification accuracies obtained using automatic method for lines, zebra crossings and kerbstones were 80.6%, 92.3% and 79.7%, respectively. Full article
(This article belongs to the Special Issue LiDAR for 3D City Modeling)
Open AccessArticle Sodium Gill Potential as a Tool to Monitor Valve Closure Behavior in Freshwater Clam Corbicula fluminea in Response to Copper
Sensors 2008, 8(9), 5250-5269; doi:10.3390/s8095250
Received: 2 July 2008 / Revised: 14 August 2008 / Accepted: 28 August 2008 / Published: 1 September 2008
Cited by 2 | PDF Full-text (512 KB) | HTML Full-text | XML Full-text
Abstract
Valve closure behavior in freshwater clam Corbicula fluminea is a biologically sensitive endpoint. The purpose of this paper was to derive an electrophysiological response model of C. fluminea to assess copper (Cu)-sodium (Na) interactions in gill membrane, whereby valve closure behavior and [...] Read more.
Valve closure behavior in freshwater clam Corbicula fluminea is a biologically sensitive endpoint. The purpose of this paper was to derive an electrophysiological response model of C. fluminea to assess copper (Cu)-sodium (Na) interactions in gill membrane, whereby valve closure behavior and Cu toxicity could be monitored. The proposed model was based on the integration of Cu bioavailability, Na and Cu internalizations, and electrochemically-based gill potentials. Based on Na active transport under non-equilibrium conditions, predicted gill potential of -8.2 mV agreed reasonably well with published the measured transepithelial potential of -7 mV in C. fluminea. Our proposed framework captured the general features observed in model applications including: (i) 50% inhibitory Cu2+ activities for Na membrane potential (ENa) and uptake rate (JNa) were estimated to be 0.072 and 0.043 mM, respectively, with a stoichiometry of 3Cu2+: 1ENa and 1JNa; (ii) the external Cu2+-dependent internal Na concentration could be parsimoniously estimated, and (iii) the site-specific clam gill potentials could be monitored. Here we provided a new approach to monitor waterborne metal toxicity to reduce the nationwide economic losses due to bans on harvesting of contaminated clam and the potential risks to the health of clams. Full article
Open AccessArticle Deriving Vegetation Dynamics of Natural Terrestrial Ecosystems from MODIS NDVI/EVI Data over Turkey
Sensors 2008, 8(9), 5270-5302; doi:10.3390/s8095270
Received: 30 July 2008 / Revised: 25 August 2008 / Accepted: 28 August 2008 / Published: 1 September 2008
Cited by 16 | PDF Full-text (3565 KB) | HTML Full-text | XML Full-text
Abstract
The 16-day composite MODIS vegetation indices (VIs) at 500-m resolution for the period between 2000 to 2007 were seasonally averaged on the basis of the estimated distribution of 16 potential natural terrestrial ecosystems (NTEs) across Turkey. Graphical and statistical analyses of the [...] Read more.
The 16-day composite MODIS vegetation indices (VIs) at 500-m resolution for the period between 2000 to 2007 were seasonally averaged on the basis of the estimated distribution of 16 potential natural terrestrial ecosystems (NTEs) across Turkey. Graphical and statistical analyses of the time-series VIs for the NTEs spatially disaggregated in terms of biogeoclimate zones and land cover types included descriptive statistics, correlations, discrete Fourier transform (DFT), time-series decomposition, and simple linear regression (SLR) models. Our spatio-temporal analyses revealed that both MODIS VIs, on average, depicted similar seasonal variations for the NTEs, with the NDVI values having higher mean and SD values. The seasonal VIs were most correlated in decreasing order for: barren/sparsely vegetated land > grassland > shrubland/woodland > forest; (sub)nival > warm temperate > alpine > cool temperate > boreal = Mediterranean; and summer > spring > autumn > winter. Most pronounced differences between the MODIS VI responses over Turkey occurred in boreal and Mediterranean climate zones and forests, and in winter (the senescence phase of the growing season). Our results showed the potential of the time-series MODIS VI datasets in the estimation and monitoring of seasonal and interannual ecosystem dynamics over Turkey that needs to be further improved and refined through systematic and extensive field measurements and validations across various biomes. Full article
Open AccessArticle Amperometric Biosensors for Real Time Assays of Organophosphates
Sensors 2008, 8(9), 5303-5312; doi:10.3390/s8095303
Received: 30 July 2008 / Revised: 27 August 2008 / Accepted: 28 August 2008 / Published: 1 September 2008
Cited by 30 | PDF Full-text (101 KB) | HTML Full-text | XML Full-text
Abstract
An amperometric biosensor based on acetylcholinesterase (AChE) immobilized in gelatin was used to develop an assay for the organophosphate paraoxon. The more traditional manner employing preincubation was used for comparison between measurement procedures, although the aim of the study was to examine [...] Read more.
An amperometric biosensor based on acetylcholinesterase (AChE) immobilized in gelatin was used to develop an assay for the organophosphate paraoxon. The more traditional manner employing preincubation was used for comparison between measurement procedures, although the aim of the study was to examine the performance of the biosensor for real time monitoring of organophosphates. The biosensor was immersed in a reaction chamber and paraoxon was injected inside. We were able to detect 200 pg of paraoxon within one minute or 2.5 ppb when the biosensor was preincubed in the sample solution for 15 minutes. The practical impact and expectations are discussed. Full article
Open AccessArticle Monolithic Active Pixel Sensors (MAPS) in a Quadruple Well Technology for Nearly 100% Fill Factor and Full CMOS Pixels
Sensors 2008, 8(9), 5336-5351; doi:10.3390/s8095336
Received: 14 July 2008 / Revised: 1 September 2008 / Accepted: 1 September 2008 / Published: 2 September 2008
Cited by 31 | PDF Full-text (456 KB) | HTML Full-text | XML Full-text
Abstract
In this paper we present a novel, quadruple well process developed in a modern 0.18 mm CMOS technology called INMAPS. On top of the standard process, we have added a deep P implant that can be used to form a deep P-well [...] Read more.
In this paper we present a novel, quadruple well process developed in a modern 0.18 mm CMOS technology called INMAPS. On top of the standard process, we have added a deep P implant that can be used to form a deep P-well and provide screening of N-wells from the P-doped epitaxial layer. This prevents the collection of radiation-induced charge by unrelated N-wells, typically ones where PMOS transistors are integrated. The design of a sensor specifically tailored to a particle physics experiment is presented, where each 50 mm pixel has over 150 PMOS and NMOS transistors. The sensor has been fabricated in the INMAPS process and first experimental evidence of the effectiveness of this process on charge collection is presented, showing a significant improvement in efficiency. Full article
(This article belongs to the Special Issue Integrated High-performance Imagers)
Open AccessArticle Neuromorphic VLSI Models of Selective Attention: From Single Chip Vision Sensors to Multi-chip Systems
Sensors 2008, 8(9), 5352-5375; doi:10.3390/s8095352
Received: 30 June 2008 / Revised: 1 September 2008 / Accepted: 2 September 2008 / Published: 3 September 2008
Cited by 16 | PDF Full-text (1013 KB) | HTML Full-text | XML Full-text
Abstract
Biological organisms perform complex selective attention operations continuously and effortlessly. These operations allow them to quickly determine the motor actions to take in response to combinations of external stimuli and internal states, and to pay attention to subsets of sensory inputs suppressing [...] Read more.
Biological organisms perform complex selective attention operations continuously and effortlessly. These operations allow them to quickly determine the motor actions to take in response to combinations of external stimuli and internal states, and to pay attention to subsets of sensory inputs suppressing non salient ones. Selective attention strategies are extremely effective in both natural and artificial systems which have to cope with large amounts of input data and have limited computational resources. One of the main computational primitives used to perform these selection operations is the Winner-Take-All (WTA) network. These types of networks are formed by arrays of coupled computational nodes that selectively amplify the strongest input signals, and suppress the weaker ones. Neuromorphic circuits are an optimal medium for constructing WTA networks and for implementing efficient hardware models of selective attention systems. In this paper we present an overview of selective attention systems based on neuromorphic WTA circuits ranging from single-chip vision sensors for selecting and tracking the position of salient features, to multi-chip systems implement saliency-map based models of selective attention. Full article
(This article belongs to the Special Issue State-of-the-Art Sensors Technology in Switzerland)
Open AccessArticle Verifying Pressure of Water on Dams, a Case Study
Sensors 2008, 8(9), 5376-5385; doi:10.3390/s8095376
Received: 10 July 2008 / Revised: 19 August 2008 / Accepted: 19 August 2008 / Published: 3 September 2008
Cited by 2 | PDF Full-text (154 KB) | HTML Full-text | XML Full-text
Abstract
Sensing and monitoring deformation pattern of dams is often one of the most effective ways to understand their safety status. The main objective of the present study is to find the extent to which rising reservoir level affects the mechanism of deformation [...] Read more.
Sensing and monitoring deformation pattern of dams is often one of the most effective ways to understand their safety status. The main objective of the present study is to find the extent to which rising reservoir level affects the mechanism of deformation of the Yamula dam under certain changes in the reservoir level conditions during the first filling period. A new dynamic deformation analysis technique was developed to analyze four geodetic monitoring records consisting of vertical and horizontal displacements of nine object points established on the dam and six reference points surrounding it, to see whether the rising reservoir level is responsible for the vertical and horizontal deformations during the first filling period. The largest displacements were determined in the middle points of the dam construction. There is an apparent linear relationship between the dam subsidence and the reservoir level. The dynamic deformation model was developed to model this situation. The model infers a causative relationship between the reservoir level and the dam deformations. The analysis of the results determines the degree of the correlation between the change in the reservoir level and the observed structural deformation of the dam. Full article
Open AccessArticle Drift and Hysteresis Characteristics of Drug Sensors Based on Ruthenium Dioxide Membrane
Sensors 2008, 8(9), 5386-5396; doi:10.3390/s8095386
Received: 1 July 2008 / Revised: 14 August 2008 / Accepted: 29 August 2008 / Published: 3 September 2008
Cited by 3 | PDF Full-text (126 KB) | HTML Full-text | XML Full-text
Abstract
The drug sensing properties of procaine and berberine drug sensors based on ruthenium dioxide thin film were investigated. Ruthenium dioxide (RuO2) membrane prepared using a sputtering method was used as substrates for the drug sensors. The procaine and berberine drug [...] Read more.
The drug sensing properties of procaine and berberine drug sensors based on ruthenium dioxide thin film were investigated. Ruthenium dioxide (RuO2) membrane prepared using a sputtering method was used as substrates for the drug sensors. The procaine and berberine drug sensors were prepared using a drug-sensitive membrane that measured the procaine and berberine concentration in a linear range from 1×10-2 M to 1×10-6 M and from 1×10-2 M to 1×10-7 M, respectively. The drift rates and hyteresis widths of these ruthenium dioxide based drug sensors were also investigated. Full article
Open AccessArticle Long-term Satellite NDVI Data Sets: Evaluating Their Ability to Detect Ecosystem Functional Changes in South America
Sensors 2008, 8(9), 5397-5425; doi:10.3390/s8095397
Received: 15 July 2008 / Revised: 1 September 2008 / Accepted: 2 September 2008 / Published: 3 September 2008
Cited by 46 | PDF Full-text (1558 KB) | HTML Full-text | XML Full-text
Abstract
In the last decades, South American ecosystems underwent important functional modifications due to climate alterations and direct human intervention on land use and land cover. Among remotely sensed data sets, NOAA-AVHRR “Normalized Difference Vegetation Index” (NDVI) represents one of the most powerful [...] Read more.
In the last decades, South American ecosystems underwent important functional modifications due to climate alterations and direct human intervention on land use and land cover. Among remotely sensed data sets, NOAA-AVHRR “Normalized Difference Vegetation Index” (NDVI) represents one of the most powerful tools to evaluate these changes thanks to their extended temporal coverage. In this paper we explored the possibilities and limitations of three commonly used NOAA-AVHRR NDVI series (PAL, GIMMS and FASIR) to detect ecosystem functional changes in the South American continent. We performed pixel-based linear regressions for four NDVI variables (average annual, maximum annual, minimum annual and intra-annual coefficient of variation) for the 1982-1999 period and (1) analyzed the convergences and divergences of significant multi-annual trends identified across all series, (2) explored the degree of aggregation of the trends using the O-ring statistic, and (3) evaluated observed trends using independent information on ecosystem functional changes in five focal regions. Several differences arose in terms of the patterns of change (the sign, localization and total number of pixels with changes). FASIR presented the highest proportion of changing pixels (32.7%) and GIMMS the lowest (16.2%). PAL and FASIR data sets showed the highest agreement, with a convergence of detected trends on 71.2% of the pixels. Even though positive and negative changes showed substantial spatial aggregation, important differences in the scale of aggregation emerged among the series, with GIMMS showing the smaller scale (≤11 pixels). The independent evaluations suggest higher accuracy in the detection of ecosystem changes among PAL and FASIR series than with GIMMS, as they detected trends that match expected shifts. In fact, this last series eliminated most of the long term patterns over the continent. For example, in the “Eastern Paraguay” and “Uruguay River margins” focal regions, the extensive changes due to land use and land cover change expansion were detected by PAL and FASIR, but completely ignored by GIMMS. Although the technical explanation of the differences remains unclear and needs further exploration, we found that the evaluation of this type of remote sensing tools should not only be focused at the level of assumptions (i.e. physical or mathematical aspects of image processing), but also at the level of results (i.e. contrasting observed patterns with independent proofs of change). We finally present the online collaborative initiative “Land ecosystem change utility for South America”, which facilitates this type of evaluations and helps to identify the most important functional changes of the continent. Full article
Open AccessArticle Analyzing Land Use Changes in the Metropolitan Jilin City of Northeastern China Using Remote Sensing and GIS
Sensors 2008, 8(9), 5449-5465; doi:10.3390/s8095449
Received: 20 July 2008 / Revised: 1 September 2008 / Accepted: 1 September 2008 / Published: 3 September 2008
Cited by 1 | PDF Full-text (471 KB) | HTML Full-text | XML Full-text
Abstract
Remote sensing and GIS have been widely employed to study temporal and spatial urban land use changes in southern and southeastern China. However, few studies have been conducted in northeastern regions. This study analyzed land use change and spatial patterns of urban [...] Read more.
Remote sensing and GIS have been widely employed to study temporal and spatial urban land use changes in southern and southeastern China. However, few studies have been conducted in northeastern regions. This study analyzed land use change and spatial patterns of urban expansion in the metropolitan area of Jilin City, located on the extension of Changbai Mountain, based on aerial photos from 1989 and 2005 Spot images. The results indicated that urban land and transportation land increased dramatically (by 94.04% and 211.20%, respectively); isolated industrial and mining land decreased moderately (by 29.54%); rural residential land increased moderately (by 26.48%); dry land and paddy fields increased slightly (by 15.68% and 11.78%, respectively); forest and orchards decreased slightly (by 5.27% and 4.61%, respectively); grasslands and unused land decreased dramatically (by 99.12% and 86.04%, respectively). Sloped dry land (more than 4 degrees) was mainly distributed on the land below 10 degrees with an east, southeastern and south sunny direction aspect, and most sloped dry land transformed to forest was located on an east aspect lower than 12 degrees, while forest changed to dry land were mainly distributed on east and south aspects lower than 10 degrees. A spatial dependency analysis of land use change showed that the increased urban land was a logarithmic function of distance to the Songhua River. This study also provided some data with spatial details about the uneven land development in the upstream areas of Songhua River basin. Full article
(This article belongs to the Special Issue Sensors for Urban Environmental Monitoring)
Open AccessArticle Mid-Infrared Tunable Resonant Cavity Enhanced Detectors
Sensors 2008, 8(9), 5466-5478; doi:10.3390/s8095466
Received: 17 July 2008 / Revised: 1 September 2008 / Accepted: 1 September 2008 / Published: 4 September 2008
Cited by 7 | PDF Full-text (945 KB) | HTML Full-text | XML Full-text
Abstract
Mid-infrared detectors that are sensitive only in a tunable narrow spectral band are presented. They are based on the Resonant Cavity Enhanced Detector (RCED) principle and employing a thin active region using IV-VI narrow gap semiconductor layers. A Fabry-Pérot cavity is formed [...] Read more.
Mid-infrared detectors that are sensitive only in a tunable narrow spectral band are presented. They are based on the Resonant Cavity Enhanced Detector (RCED) principle and employing a thin active region using IV-VI narrow gap semiconductor layers. A Fabry-Pérot cavity is formed by two mirrors. The active layer is grown onto one mirror, while the second mirror can be displaced. This changes the cavity length thus shifting the resonances where the detector is sensitive. Using electrostatically actuated MEMS micromirrors, a very compact tunable detector system has been fabricated. Mirror movements of more than 3 μm at 30V are obtained. With these mirrors, detectors with a wavelength tuning range of about 0.7 μm have been realized. Single detectors can be used in mid-infrared micro spectrometers, while a detector arrangement in an array makes it possible to realize Adaptive Focal Plane Arrays (AFPA). Full article
(This article belongs to the Special Issue State-of-the-Art Sensors Technology in Switzerland)
Open AccessArticle Impact of Soil Moisture Dynamics on ASAR σo Signatures and Its Spatial Variability Observed over the Tibetan Plateau
Sensors 2008, 8(9), 5479-5491; doi:10.3390/s8095479
Received: 30 June 2008 / Revised: 20 August 2008 / Accepted: 28 August 2008 / Published: 3 September 2008
Cited by 11 | PDF Full-text (821 KB) | HTML Full-text | XML Full-text
Abstract
This paper reports on the analysis of a 2.5 year-long time series of ASAR wide swath mode (WSM) observations for characterizing the soil moisture dynamics. The employed ASAR WSM data set consists of 152 VV-polarized scenes acquired in the period between April [...] Read more.
This paper reports on the analysis of a 2.5 year-long time series of ASAR wide swath mode (WSM) observations for characterizing the soil moisture dynamics. The employed ASAR WSM data set consists of 152 VV-polarized scenes acquired in the period between April 2005 and September 2007 over the Naqu river basin located on the Tibetan Plateau. For four different spatial domains, with areas of 30x30 km2, 5x5 km2 and (two domains of) 1x1 km2, the mean backscatter (σo) and the standard deviation (stdev) have been computed for each ASAR acquisition. Comparison of the mean σo values with the stdev values results in a specific triangular distribution of data points for all spatial domains. Analysis of the mean σo and stdev with respect to in-situ soil moisture measurements demonstrates that this triangular shaped distribution can be explained by soil moisture dynamics during monsoon and winter periods. This shows that the relationship between the spatial mean soil moisture and variability is not uniquely defined and may change throughout seasons. Downscaling of coarse resolution soil moisture products should, therefore, be ideally based on additional near real time data sources. In this context, the presented results could form a basis for the development of SAR-based soil moisture downscaling methodologies. Full article
Open AccessArticle An Amperometric Biosensor for Uric Acid Determination Prepared From Uricase Immobilized in Polyaniline-Polypyrrole Film
Sensors 2008, 8(9), 5492-5500; doi:10.3390/s8095492
Received: 17 July 2008 / Revised: 14 August 2008 / Accepted: 26 August 2008 / Published: 4 September 2008
Cited by 53 | PDF Full-text (216 KB) | HTML Full-text | XML Full-text
Abstract
A new amperometric uric acid biosensor was developed by immobilizing uricase by a glutaraldehyde crosslinking procedure on polyaniline-polypyrrole (pani-ppy) composite film on the surface of a platinum electrode. Determination of uric acid was performed by the oxidation of enzymatically generated H2 [...] Read more.
A new amperometric uric acid biosensor was developed by immobilizing uricase by a glutaraldehyde crosslinking procedure on polyaniline-polypyrrole (pani-ppy) composite film on the surface of a platinum electrode. Determination of uric acid was performed by the oxidation of enzymatically generated H2O2 at 0.4 V vs. Ag/AgCl. The linear working range of the biosensor was 2.5×10-6 – 8.5×10-5 M and the response time was about 70 s. The effects of pH, temperature were investigated and optimum parameters were found to be 9.0, 55 oC, respectively. The stability and reproducibility of the enzyme electrode have been also studied. Full article
Open AccessArticle Integrated Design and Implementation of Embedded Control Systems with Scilab
Sensors 2008, 8(9), 5501-5515; doi:10.3390/s8095501
Received: 2 June 2008 / Revised: 25 August 2008 / Accepted: 1 September 2008 / Published: 5 September 2008
Cited by 12 | PDF Full-text (329 KB) | HTML Full-text | XML Full-text
Abstract
Embedded systems are playing an increasingly important role in control engineering. Despite their popularity, embedded systems are generally subject to resource constraints and it is therefore difficult to build complex control systems on embedded platforms. Traditionally, the design and implementation of control [...] Read more.
Embedded systems are playing an increasingly important role in control engineering. Despite their popularity, embedded systems are generally subject to resource constraints and it is therefore difficult to build complex control systems on embedded platforms. Traditionally, the design and implementation of control systems are often separated, which causes the development of embedded control systems to be highly timeconsuming and costly. To address these problems, this paper presents a low-cost, reusable, reconfigurable platform that enables integrated design and implementation of embedded control systems. To minimize the cost, free and open source software packages such as Linux and Scilab are used. Scilab is ported to the embedded ARM-Linux system. The drivers for interfacing Scilab with several communication protocols including serial, Ethernet, and Modbus are developed. Experiments are conducted to test the developed embedded platform. The use of Scilab enables implementation of complex control algorithms on embedded platforms. With the developed platform, it is possible to perform all phases of the development cycle of embedded control systems in a unified environment, thus facilitating the reduction of development time and cost. Full article
Open AccessArticle A Role for Adenosine A1 Receptors in GABA and NMDA-Receptor Mediated Modulation of Dopamine Release: Studies Using Fast Cyclic Voltammetry
Sensors 2008, 8(9), 5516-5534; doi:10.3390/s8095516
Received: 16 June 2008 / Revised: 1 September 2008 / Accepted: 2 September 2008 / Published: 5 September 2008
Cited by 2 | PDF Full-text (1528 KB) | HTML Full-text | XML Full-text
Abstract
In the striatum many neurotransmitters including GABA, glutamate, acetylcholine, dopamine, nitric oxide and adenosine interact to regulate synaptic transmission. Dopamine release in the striatum is regulated by a number of pre- and postsynaptic receptors including adenosine. We have recently shown using isolated [...] Read more.
In the striatum many neurotransmitters including GABA, glutamate, acetylcholine, dopamine, nitric oxide and adenosine interact to regulate synaptic transmission. Dopamine release in the striatum is regulated by a number of pre- and postsynaptic receptors including adenosine. We have recently shown using isolated rat striatal slices, and the technique of fast cyclic voltammetry, that adenosine A1 receptor-mediated inhibition of dopamine release is modulated by dopamine D1 receptors. In the present study we have investigated the influence of NMDA and GABA receptor activation on the modulation of electrically stimulated dopamine release by adenosine. Application of the adenosine A1 receptor agonist, N6-cyclopentyladenosine (CPA), concentration-dependently inhibited dopamine release to a maxiumum of 50%. Perfusion of the glutamate receptor agonist, NMDA, in low magnesium, caused a rapid and concentration-dependent inhibition of dopamine release. Prior perfusion with the adenosine A1 receptor antagonist, DPCPX, significantly reduced the effect of 5 mM and 10 mM NMDA on dopamine release. The GABAA receptor agonist, isoguvacine, had a significant concentration-dependent inhibitory effect on dopamine release which was reversed by prior application of the GABAA receptor antagonist, picrotoxin, but not DPCPX. Finally inhibition of dopamine release by CPA (1mM) was significantly enhanced by prior perfusion with picrotoxin. These data demonstrate an important role for GABA, NMDA and adenosine in the modulation of dopamine release. Full article
Open AccessArticle The Graphical Cadastre Problem in Turkey: The Case of Trabzon Province
Sensors 2008, 8(9), 5560-5575; doi:10.3390/s8095560
Received: 28 May 2008 / Revised: 19 August 2008 / Accepted: 2 September 2008 / Published: 11 September 2008
Cited by 12 | PDF Full-text (370 KB) | HTML Full-text | XML Full-text
Abstract
Cadastral projects in Turkey have been accelerated in recent years by the involvement of the private sector. These projects aim at completing the country’s cadastre, along with producing bases in standards that could be a foundation for Land Registry and Cadastre Information [...] Read more.
Cadastral projects in Turkey have been accelerated in recent years by the involvement of the private sector. These projects aim at completing the country’s cadastre, along with producing bases in standards that could be a foundation for Land Registry and Cadastre Information System (LRCIS). It is possible to produce cadastral data with today’s technological means. In this context, three dimensional cadastre data can be properly produced, especially in digital cadastre projects with the required point accuracy. Nevertheless this is not enough for LRCIS. The cadastre bases that have been produced so far by different methods with different scales and bases, with or without coordinates, should also be converted into digital form based on National Basic GPS Network of Turkey (NBGN) in required point-location accuracy. As the result of evaluation of graphical cadastre bases produced without coordinates, actual land measurements, and information obtained from sheets and field book data together, it was found out that there are significant base problems in the graphical maps. These bases, comprising 20% of Turkey’s cadastre constitutes the most important bottleneck of completing the country’s cadastre. In the scope of this paper, the possibilities of converting the field book measurement values of graphic cadastre bases into digital forms in national coordinate system by comparing them with actual land measurements are investigated, along with Turkey’s Cadastre and its problems. Full article
Open AccessArticle Quantitative Hyperspectral Reflectance Imaging
Sensors 2008, 8(9), 5576-5618; doi:10.3390/s8095576
Received: 31 July 2008 / Revised: 2 September 2008 / Accepted: 9 September 2008 / Published: 11 September 2008
Cited by 34 | PDF Full-text (3712 KB) | HTML Full-text | XML Full-text
Abstract
Hyperspectral imaging is a non-destructive optical analysis technique that can for instance be used to obtain information from cultural heritage objects unavailable with conventional colour or multi-spectral photography. This technique can be used to distinguish and recognize materials, to enhance the visibility [...] Read more.
Hyperspectral imaging is a non-destructive optical analysis technique that can for instance be used to obtain information from cultural heritage objects unavailable with conventional colour or multi-spectral photography. This technique can be used to distinguish and recognize materials, to enhance the visibility of faint or obscured features, to detect signs of degradation and study the effect of environmental conditions on the object. We describe the basic concept, working principles, construction and performance of a laboratory instrument specifically developed for the analysis of historical documents. The instrument measures calibrated spectral reflectance images at 70 wavelengths ranging from 365 to 1100 nm (near-ultraviolet, visible and near-infrared). By using a wavelength tunable narrow-bandwidth light-source, the light energy used to illuminate the measured object is minimal, so that any light-induced degradation can be excluded. Basic analysis of the hyperspectral data includes a qualitative comparison of the spectral images and the extraction of quantitative data such as mean spectral reflectance curves and statistical information from user-defined regions-of-interest. More sophisticated mathematical feature extraction and classification techniques can be used to map areas on the document, where different types of ink had been applied or where one ink shows various degrees of degradation. The developed quantitative hyperspectral imager is currently in use by the Nationaal Archief (National Archives of The Netherlands) to study degradation effects of artificial samples and original documents, exposed in their permanent exhibition area or stored in their deposit rooms. Full article
Open AccessArticle Amperometric Sensor for Detection of Chloride Ions
Sensors 2008, 8(9), 5619-5636; doi:10.3390/s8095619
Received: 31 July 2008 / Revised: 9 September 2008 / Accepted: 11 September 2008 / Published: 15 September 2008
Cited by 9 | PDF Full-text (3647 KB) | HTML Full-text | XML Full-text
Abstract
Chloride ion sensing is important in many fields such as clinical diagnosis, environmental monitoring and industrial applications. We have measured chloride ions at a carbon paste electrode (CPE) and at a CPE modified with solid AgNO3, a solution of AgNO [...] Read more.
Chloride ion sensing is important in many fields such as clinical diagnosis, environmental monitoring and industrial applications. We have measured chloride ions at a carbon paste electrode (CPE) and at a CPE modified with solid AgNO3, a solution of AgNO3 and/or solid silver particles. Detection limits (3 S/N) for chloride ions were 100 μM, 100 μM and 10 μM for solid AgNO3, solution of AgNO3 and/or solid silver particles, respectively. The CPE modified with silver particles is the most sensitive to the presence chloride ions. After that we approached to the miniaturization of the whole electrochemical instrument. Measurements were carried out on miniaturized instrument consisting of a potentiostat with dimensions 35 × 166 × 125 mm, screen printed electrodes, a peristaltic pump and a PC with control software. Under the most suitable experimental conditions (Britton-Robinson buffer, pH 1.8 and working electrode potential 550 mV) we estimated the limit of detection (3 S/N) as 500 nM. Full article
Open AccessArticle Immobilization of the Enzyme Glucose Oxidase on Both Bulk and Porous SiO2 Surfaces
Sensors 2008, 8(9), 5637-5648; doi:10.3390/s8095637
Received: 6 August 2008 / Revised: 26 August 2008 / Accepted: 10 September 2008 / Published: 15 September 2008
Cited by 19 | PDF Full-text (349 KB) | HTML Full-text | XML Full-text
Abstract
Silicon dioxide surfaces, both bulk and porous, were used to anchor the enzyme glucose oxidase. The immobilization protocol was optimized and the samples characterized using X-ray Photoelectron Spectroscopy, Energy Dispersive X-rays coupled to scanning electron microscopy and enzymatic activity measurements. We show [...] Read more.
Silicon dioxide surfaces, both bulk and porous, were used to anchor the enzyme glucose oxidase. The immobilization protocol was optimized and the samples characterized using X-ray Photoelectron Spectroscopy, Energy Dispersive X-rays coupled to scanning electron microscopy and enzymatic activity measurements. We show that a uniform layer was obtained by activating the oxide before immobilization. X-ray Photoelectron Spectroscopy measurements carried out on bulk oxide showed that the silicon substrate signal was fully screened after the enzyme deposition showing the absence of uncovered surface regions. The enzyme presence was detected monitoring both the C 1s and N 1s signals. Finally, enzymatic activity measurements confirmed that the glucose oxidase activity was preserved after immobilization and maintained after three months of shelf life if the sample was properly stored. The importance of using porous silicon oxide to maximize the surface area was also evidenced. Full article
Open AccessArticle Electrochemical Behaviors of Methylene Blue on DNA Modified Electrode and Its Application to the Detection of PCR Product from NOS Sequence
Sensors 2008, 8(9), 5649-5660; doi:10.3390/s8095649
Received: 17 July 2008 / Revised: 1 September 2008 / Accepted: 9 September 2008 / Published: 15 September 2008
Cited by 33 | PDF Full-text (117 KB) | HTML Full-text | XML Full-text
Abstract
An electrochemical DNA biosensor for the detection of NOS gene sequences from genetically modified organisms (GMOs) is presented in this paper. Single-stranded DNA (ssDNA) was covalently attached through the carboxylate ester formed by the 3’- hydroxy end of the DNA with the [...] Read more.
An electrochemical DNA biosensor for the detection of NOS gene sequences from genetically modified organisms (GMOs) is presented in this paper. Single-stranded DNA (ssDNA) was covalently attached through the carboxylate ester formed by the 3’- hydroxy end of the DNA with the carboxyl of a mercaptoacetic acid self-assembled monolayer-modified gold electrode using N-hydroxysuccinimide (NHS) and N-(3-dimethylaminopropyl)-N’-ethylcarbodiimide hydrochloride (EDC) as linkers. The electrochemical behavior of methylene blue (MB) on the ssDNA and dsDNA modified gold electrode were carefully studied. Compared with ssDNA/Au electrode, an increase of redox peak current of MB on dsDNA/Au electrode was found, which could be further used for monitoring the recognition of DNA hybridization. Based on this result, the polymerase chain reaction (PCR) product of the common inserts NOS terminator from real GMOs samples was detected successfully. Full article
Open AccessArticle An Immunosensing System Using Stilbene Glycoside as a Fluorogenic Substrate for an Enzymatic Reaction Model
Sensors 2008, 8(9), 5661-5672; doi:10.3390/s8095661
Received: 21 July 2008 / Revised: 4 September 2008 / Accepted: 11 September 2008 / Published: 15 September 2008
Cited by 1 | PDF Full-text (104 KB) | HTML Full-text | XML Full-text
Abstract
A natural product, stilbene glycoside (2,3,5,4’-tetrahydroxydiphenylethylene-2-O-glucoside, TBG), has been evaluated for the first time as a potential substrate for horseradish peroxidase (HRP)-catalyzed fluorogenic reactions. The properties of TBG as a fluorogenic substrate for HRP and its application in a fluorometric enzyme-linked immunosensing [...] Read more.
A natural product, stilbene glycoside (2,3,5,4’-tetrahydroxydiphenylethylene-2-O-glucoside, TBG), has been evaluated for the first time as a potential substrate for horseradish peroxidase (HRP)-catalyzed fluorogenic reactions. The properties of TBG as a fluorogenic substrate for HRP and its application in a fluorometric enzyme-linked immunosensing system were compared with commercially available substrates such as p-hydroxyphenylpropionic acid (pHPPA), chavicol and Amplex red using Brucella melitensis antibody (BrAb) as a model analyte. The immunosensing body based on HRP-BrAb was constructed by dispersing graphite, BrAg and paraffin wax at room temperature. In a competitive immunoassay procedure, the BrAb competed with HRP-BrAb to react with the immobilized BrAg. In the enzymatic reaction, the binding HRP-BrAb on the sensing body surface can catalyze the polymerization reaction of TBG by H2O2 forming fluorescent dimers and causing an increase in fluorescence intensity. TBG showed comparable ability for HRP detection and its enzyme-linked immunosensing reaction system, in a linear detection ranging of 3.5´10-8~7.6´10-6g/L and with a detection limit of 1.7´10-9 g/L. The immobilized biocomposite surface could be regenerated with excellent reproducibility (RSD=3.8%) by simply polishing with an alumina paper. The proposed immunosensing system has been used to determine the BrAb in rabbit serum samples with satisfactory results. Full article
Open AccessArticle Value Benefit Analysis Software and Its Application in Bolu-Lake Abant Natural Park
Sensors 2008, 8(9), 5745-5758; doi:10.3390/s8095745
Received: 12 August 2008 / Revised: 1 September 2008 / Accepted: 5 September 2008 / Published: 17 September 2008
Cited by 4 | PDF Full-text (370 KB) | HTML Full-text | XML Full-text
Abstract
Value benefit analysis (VBA) is a psychometric instrument for finding the best compromise in forestry multiple-use planning, when the multiple objectives cannot be expressed in the same physical or monetary unit. It insures a systematic assessment of the consequences of proposed alternatives [...] Read more.
Value benefit analysis (VBA) is a psychometric instrument for finding the best compromise in forestry multiple-use planning, when the multiple objectives cannot be expressed in the same physical or monetary unit. It insures a systematic assessment of the consequences of proposed alternatives and thoroughly documents the decision process. The method leads to a ranking of alternatives based upon weighting of the objectives and evaluation of the contribution of each alternative to these objectives. The use of the method is illustrated with hypothetical data about Bolu-Lake Abant Natural Park (BLANP). In this study, in addition, computer software controlling the confidence was created. This software puts into practice the method proposed by Churchman and Ackoff, and determines the significance of the alternatives quickly and accurately. Full article
Open AccessArticle Electrical Characterization of Microelectromechanical Silicon Carbide Resonators
Sensors 2008, 8(9), 5759-5774; doi:10.3390/s8095759
Received: 14 July 2008 / Revised: 10 September 2008 / Accepted: 12 September 2008 / Published: 17 September 2008
Cited by 8 | PDF Full-text (724 KB) | HTML Full-text | XML Full-text
Abstract
This manuscript describes the findings of a study to investigate the performance of SiC MEMS resonators with respect to resonant frequency and quality factor under a variety of testing conditions, including various ambient pressures, AC drive voltages, bias potentials and temperatures. The [...] Read more.
This manuscript describes the findings of a study to investigate the performance of SiC MEMS resonators with respect to resonant frequency and quality factor under a variety of testing conditions, including various ambient pressures, AC drive voltages, bias potentials and temperatures. The sample set included both single-crystal and polycrystalline 3C-SiC lateral resonators. The experimental results show that operation at reduced pressures increases the resonant frequency as damping due to the gas-rarefaction effect becomes significant. Both DC bias and AC drive voltages result in nonlinearities, but the AC drive voltage is more sensitive to noise. The AC voltage has a voltage coefficient of 1~4ppm/V at a DC bias of 40V. The coefficient of DC bias is about -11ppm/V to - 21ppm/V for poly-SiC, which is more than a factor of two better than a similarly designed polysilicon resonator (-54 ppm/V). The effective stiffness of the resonator decreases (softens) as the bias potential is increased, but increases (hardens) as drive voltage increase when scan is from low to high frequency. The resonant frequency decreases slightly with increasing temperature, exhibiting a temperature coefficient of -22 ppm/oC, between 22oC and 60oC. The thermal expansion mismatch between the SiC device and the Si substrate could be a reason that thermal coefficient for these SiC resonators is about twofold higher than similar polysilicon resonators. However, the Qs appear to exhibit no temperature dependence in this range. Full article
Open AccessArticle Use of Fe3O4 Nanoparticles for Enhancement of Biosensor Response to the Herbicide 2,4-Dichlorophenoxyacetic Acid
Sensors 2008, 8(9), 5775-5791; doi:10.3390/s8095775
Received: 29 July 2008 / Revised: 30 August 2008 / Accepted: 10 September 2008 / Published: 18 September 2008
Cited by 27 | PDF Full-text (2469 KB) | HTML Full-text | XML Full-text
Abstract
Magnetic nanoparticles of Fe3O4 were synthesized and characterized using transmission electron microscopy and X-ray diffraction. The Fe3O4 nanoparticles were found to have an average diameter of 5.48 ±1.37 nm. An electrochemical biosensor based on immobilized alkaline [...] Read more.
Magnetic nanoparticles of Fe3O4 were synthesized and characterized using transmission electron microscopy and X-ray diffraction. The Fe3O4 nanoparticles were found to have an average diameter of 5.48 ±1.37 nm. An electrochemical biosensor based on immobilized alkaline phosphatase (ALP) and Fe3O4 nanoparticles was studied. The amperometric biosensor was based on the reaction of ALP with the substrate ascorbic acid 2-phosphate (AA2P). The incorporation of the Fe3O4 nanoparticles together with ALP into a sol gel/chitosan biosensor membrane has led to the enhancement of the biosensor response, with an improved linear response range to the substrate AA2P (5-120 μM) and increased sensitivity. Using the inhibition property of the ALP, the biosensor was applied to the determination of the herbicide 2,4-dichlorophenoxyacetic acid (2,4-D). The use of Fe3O4 nanoparticles gives a two-fold improvement in the sensitivity towards 2,4-D, with a linear response range of 0.5-30 μgL-1. Exposure of the biosensor to other toxicants such as heavy metals demonstrated only slight interference from metals such as Hg2+, Cu2+, Ag2+ and Pb2+. The biosensor was shown to be useful for the determination of the herbicide 2, 4-D because good recovery of 95-100 percent was obtained, even though the analysis was performed in water samples with a complex matrix. Furthermore, the results from the analysis of 2,4-D in water samples using the biosensor correlated well with a HPLC method. Full article
Open AccessArticle Electrochemical Preparation of a Molecularly Imprinted Polypyrrole-modified Pencil Graphite Electrode for Determination of Ascorbic Acid
Sensors 2008, 8(9), 5792-5805; doi:10.3390/s8095792
Received: 10 August 2008 / Revised: 30 August 2008 / Accepted: 12 September 2008 / Published: 18 September 2008
Cited by 66 | PDF Full-text (136 KB) | HTML Full-text | XML Full-text
Abstract
A molecularly imprinted polymer (MIP) polypyrrole (PPy)-based film was fabricated for the determination of ascorbic acid. The film was prepared by incorporation of a template molecule (ascorbic acid) during the electropolymerization of pyrrole onto a pencil graphite electrode (PGE) in aqueous solution [...] Read more.
A molecularly imprinted polymer (MIP) polypyrrole (PPy)-based film was fabricated for the determination of ascorbic acid. The film was prepared by incorporation of a template molecule (ascorbic acid) during the electropolymerization of pyrrole onto a pencil graphite electrode (PGE) in aqueous solution using a cyclic voltammetry method. The performance of the imprinted and non-imprinted (NIP) films was evaluated by differential pulse voltammetry (DPV). The effect of pH, monomer and template concentrations, electropolymerization cycles and interferents on the performance of the MIP electrode was investigated and optimized. The molecularly imprinted film exhibited a high selectivity and sensitivity toward ascorbic acid. The DPV peak current showed a linear dependence on the ascorbic acid concentration and a linear calibration curve was obtained in the range of 0.25 to 7.0 mM of ascorbic acid with a correlation coefficient of 0.9946. The detection limit (3σ) was determined as 7.4x10-5 M (S/N=3). The molecularly-imprinted polypyrrole-modified pencil graphite electrode showed a stable and reproducible response, without any influence of interferents commonly existing in pharmaceutical samples. The proposed method is simple and quick. The PPy electrodes have a low response time, good mechanical stability and are disposable simple to construct. Full article
Open AccessArticle Voltammetric Detection of Urea on an Ag-Modified Zeolite-Expanded Graphite-Epoxy Composite Electrode
Sensors 2008, 8(9), 5806-5819; doi:10.3390/s8095806
Received: 23 August 2008 / Revised: 13 September 2008 / Accepted: 18 September 2008 / Published: 22 September 2008
Cited by 20 | PDF Full-text (454 KB) | HTML Full-text | XML Full-text
Abstract
In this paper, a modified expanded graphite composite electrode based on natural zeolitic volcanic tuff modified with silver (EG-Ag-Z-Epoxy) was developed. Cyclic voltammetry measurements revealed a reasonably fast electron transfer and a good stability of the electrode in 0.1 M NaOH supporting [...] Read more.
In this paper, a modified expanded graphite composite electrode based on natural zeolitic volcanic tuff modified with silver (EG-Ag-Z-Epoxy) was developed. Cyclic voltammetry measurements revealed a reasonably fast electron transfer and a good stability of the electrode in 0.1 M NaOH supporting electrolyte. This modified electrode exhibited moderate electrocatalytic effect towards urea oxidation, allowing its determination in aqueous solution. The linear dependence of the current versus urea concentration was reached using square-wave voltammetry in the concentrations range of urea between 0.2 to 1.4 mM, with a relatively low limit of detection of 0.05 mM. A moderate enhancement of electroanalytical sensitivity for the determination of urea at EG-Ag-Z-Epoxy electrode was reached by applying a chemical preconcentration step prior to voltammetric/amperometric quantification. Full article
Open AccessArticle Remote Water Temperature Measurements Based on Brillouin Scattering with a Frequency Doubled Pulsed Yb:doped Fiber Amplifier
Sensors 2008, 8(9), 5820-5831; doi:10.3390/s8095820
Received: 14 August 2008 / Revised: 4 September 2008 / Accepted: 17 September 2008 / Published: 22 September 2008
Cited by 15 | PDF Full-text (1222 KB) | HTML Full-text | XML Full-text
Abstract
Temperature profiles of the ocean are of interest for weather forecasts, climate studies and oceanography in general. Currently, mostly in situ techniques such as fixed buoys or bathythermographs deliver oceanic temperature profiles. A LIDAR method based on Brillouin scattering is an attractive [...] Read more.
Temperature profiles of the ocean are of interest for weather forecasts, climate studies and oceanography in general. Currently, mostly in situ techniques such as fixed buoys or bathythermographs deliver oceanic temperature profiles. A LIDAR method based on Brillouin scattering is an attractive alternative for remote sensing of such water temperature profiles. It makes it possible to deliver cost-effective on-line data covering an extended region of the ocean. The temperature measurement is based on spontaneous Brillouin scattering in water. In this contribution, we present the first water temperature measurements using a Yb:doped pulsed fiber amplifier. The fiber amplifier is a custom designed device which can be operated in a vibrational environment while emitting narrow bandwidth laser pulses. The device shows promising performance and demonstrates the feasibility of this approach. Furthermore, the current status of the receiver is briefly discussed; it is based on an excited state Faraday anomalous dispersion optical filter. Full article
(This article belongs to the Special Issue Ocean Remote Sensing)
Open AccessArticle A Voltammetric Biosensor Based on Glassy Carbon Electrodes Modified with Single-Walled Carbon Nanotubes/Hemoglobin for Detection of Acrylamide in Water Extracts from Potato Crisps
Sensors 2008, 8(9), 5832-5844; doi:10.3390/s8095832
Received: 1 August 2008 / Revised: 12 September 2008 / Accepted: 18 September 2008 / Published: 23 September 2008
Cited by 17 | PDF Full-text (200 KB) | HTML Full-text | XML Full-text
Abstract
The presence of toxic acrylamide in a wide range of food products such as potato crisps, French fries or bread has been confirmed by Swedish scientists from Stockholm University. The neurotoxicity, possible carcinogenicity of this compound and its metabolites compels us to [...] Read more.
The presence of toxic acrylamide in a wide range of food products such as potato crisps, French fries or bread has been confirmed by Swedish scientists from Stockholm University. The neurotoxicity, possible carcinogenicity of this compound and its metabolites compels us to control them by quantitative and qualitative assays. Acrylamide forms adduct with hemoglobin (Hb) as a result of the reaction the -NH2 group of the Nterminal valine with acrylamide. In this work we present the use of glassy carbon electrodes coated with single-walled carbon nanotubes (SWCNTs) and Hb for voltammetric detection of acrylamide in water solutions. The electrodes presented a very low detection limit (1.0×10-9 M). The validation made in the matrix obtained by water extraction of potato crisps showed that the electrodes presented are suitable for the direct determination of acrylamide in food samples. Full article
Open AccessArticle Fabrication of Pillar Shaped Electrode Arrays for Artificial Retinal Implants
Sensors 2008, 8(9), 5845-5856; doi:10.3390/s8095845
Received: 21 August 2008 / Revised: 22 September 2008 / Accepted: 23 September 2008 / Published: 24 September 2008
Cited by 12 | PDF Full-text (1553 KB) | HTML Full-text | XML Full-text
Abstract
Polyimide has been widely applied to neural prosthetic devices, such as the retinal implants, due to its well-known biocompatibility and ability to be micropatterned. However, planar films of polyimide that are typically employed show a limited ability in reducing the distance between [...] Read more.
Polyimide has been widely applied to neural prosthetic devices, such as the retinal implants, due to its well-known biocompatibility and ability to be micropatterned. However, planar films of polyimide that are typically employed show a limited ability in reducing the distance between electrodes and targeting cell layers, which limits site resolution for effective multi-channel stimulation. In this paper, we report a newly designed device with a pillar structure that more effectively interfaces with the target. Electrode arrays were successfully fabricated and safely implanted inside the rabbit eye in suprachoroidal space. Optical Coherence Tomography (OCT) showed well-preserved pillar structures of the electrode without damage. Bipolar stimulation was applied through paired sites (6:1) and the neural responses were successfully recorded from several regions in the visual cortex. Electrically evoked cortical potential by the pillar electrode array stimulation were compared to visual evoked potential under full-field light stimulation. Full article
Open AccessArticle Determination of the Content of Heavy Metals in Pyrite Contaminated Soil and Plants
Sensors 2008, 8(9), 5857-5865; doi:10.3390/s8095857
Received: 3 July 2008 / Revised: 7 July 2008 / Accepted: 8 July 2008 / Published: 24 September 2008
Cited by 9 | PDF Full-text (68 KB) | HTML Full-text | XML Full-text
Abstract
Determination of a pyrite contaminated soil texture, content of heavy metals in the soil and soil pH, was the aim in the investigation. Acidification of damaged soil was corrected by calcium carbonate. Mineral nutrients and organic matter (NPK, dung, earthworm cast, straw [...] Read more.
Determination of a pyrite contaminated soil texture, content of heavy metals in the soil and soil pH, was the aim in the investigation. Acidification of damaged soil was corrected by calcium carbonate. Mineral nutrients and organic matter (NPK, dung, earthworm cast, straw and coal dust) were added to damaged soil. Afterwards, the soil was used for oat production. Determination of total heavy metal contents (Cu, Pb, Zn, Fe) in soil was performed by atomic absorption spectrofotometry. Plant material (stems, seeds ) was analysed, too. Total concentration of the heavy metals in the plant material were greater than in crop obtained in unaffected soil. Full article
Open AccessArticle A New Approach for Structural Monitoring of Large Dams with a Three-Dimensional Laser Scanner
Sensors 2008, 8(9), 5866-5883; doi:10.3390/s8095866
Received: 29 August 2008 / Revised: 19 September 2008 / Accepted: 23 September 2008 / Published: 24 September 2008
Cited by 38 | PDF Full-text (674 KB) | HTML Full-text | XML Full-text
Abstract
Driven by progress in sensor technology, computer methods and data processing capabilities, 3D laser scanning has found a wide range of new application fields in recent years. Particularly, monitoring the static and dynamic behaviour of large dams has always been a topic [...] Read more.
Driven by progress in sensor technology, computer methods and data processing capabilities, 3D laser scanning has found a wide range of new application fields in recent years. Particularly, monitoring the static and dynamic behaviour of large dams has always been a topic of great importance, due to the impact these structures have on the whole landscape where they are built. The main goal of this paper is to show the relevance and novelty of the laserscanning methodology developed, which incorporates different statistical and modelling approaches not considered until now. As a result, the methods proposed in this paper have provided the measurement and monitoring of the large “Las Cogotas” dam (Avila, Spain). Full article
Open AccessArticle Tomographic Imaging of a Forested Area By Airborne Multi-Baseline P-Band SAR
Sensors 2008, 8(9), 5884-5896; doi:10.3390/s8095884
Received: 30 May 2008 / Revised: 29 August 2008 / Accepted: 18 September 2008 / Published: 24 September 2008
Cited by 16 | PDF Full-text (9604 KB) | HTML Full-text | XML Full-text
Abstract
In recent years, various attempts have been undertaken to obtain information about the structure of forested areas from multi-baseline synthetic aperture radar data. Tomographic processing of such data has been demonstrated for airborne L-band data but the quality of the focused tomographic [...] Read more.
In recent years, various attempts have been undertaken to obtain information about the structure of forested areas from multi-baseline synthetic aperture radar data. Tomographic processing of such data has been demonstrated for airborne L-band data but the quality of the focused tomographic images is limited by several factors. In particular, the common Fourierbased focusing methods are susceptible to irregular and sparse sampling, two problems, that are unavoidable in case of multi-pass, multi-baseline SAR data acquired by an airborne system. In this paper, a tomographic focusing method based on the time-domain back-projection algorithm is proposed, which maintains the geometric relationship between the original sensor positions and the imaged target and is therefore able to cope with irregular sampling without introducing any approximations with respect to the geometry. The tomographic focusing quality is assessed by analysing the impulse response of simulated point targets and an in-scene corner reflector. And, in particular, several tomographic slices of a volume representing a forested area are given. The respective P-band tomographic data set consisting of eleven flight tracks has been acquired by the airborne E-SAR sensor of the German Aerospace Center (DLR). Full article
(This article belongs to the Special Issue Synthetic Aperture Radar (SAR))
Open AccessArticle Structural Simulation of a Bone-Prosthesis System of the Knee Joint
Sensors 2008, 8(9), 5897-5926; doi:10.3390/s8095897
Received: 14 July 2008 / Revised: 19 September 2008 / Accepted: 22 September 2008 / Published: 24 September 2008
Cited by 3 | PDF Full-text (2362 KB) | HTML Full-text | XML Full-text
Abstract
In surgical knee replacement, the damaged knee joint is replaced with artificial prostheses. An accurate clinical evaluation must be carried out before applying knee prostheses to ensure optimal outcome from surgical operations and to reduce the probability of having long-term problems. [...] Read more.
In surgical knee replacement, the damaged knee joint is replaced with artificial prostheses. An accurate clinical evaluation must be carried out before applying knee prostheses to ensure optimal outcome from surgical operations and to reduce the probability of having long-term problems. Useful information can be inferred from estimates of the stress acting onto the bone-prosthesis system of the knee joint. This information can be exploited to tailor the prosthesis to the patient’s anatomy. We present a compound system for pre-operative surgical planning based on structural simulation of the bone-prosthesis system, exploiting patient-specific data. Full article
(This article belongs to the Special Issue Medical Images Processing)
Open AccessArticle Influence of Fluid Cell Design on the Frequency Response of AFM Microcantilevers in Liquid Media
Sensors 2008, 8(9), 5927-5941; doi:10.3390/s8095927
Received: 5 August 2008 / Revised: 10 September 2008 / Accepted: 12 September 2008 / Published: 25 September 2008
Cited by 10 | PDF Full-text (328 KB) | HTML Full-text | XML Full-text
Abstract
A study of the frequency response of AFM microcantilevers in liquid media contained in a commercial fluid cell is presented. Such systems exhibit complicated dynamics which are often not well described by available theories. Their dynamic behavior has a direct effect on [...] Read more.
A study of the frequency response of AFM microcantilevers in liquid media contained in a commercial fluid cell is presented. Such systems exhibit complicated dynamics which are often not well described by available theories. Their dynamic behavior has a direct effect on the use of the AFM in dynamic mode while imaging in liquid or while extracting the rheological properties of the fluid. We explore the issues related to the design of the cantilever holder/fluid cell and propose an approach for evaluating, minimizing and recognizing the ultimate limitations of commercial cantilever holders. A technique for estimating the frequency response spectrum of the fluid cell itself from experimental data is presented. This spectrum can then be used to evaluate whether or not the fluid cell is suited for the desired purpose. Full article
Open AccessArticle Color Changes of UHT Milk During Storage
Sensors 2008, 8(9), 5961-5974; doi:10.3390/s8095961
Received: 17 July 2008 / Revised: 19 September 2008 / Accepted: 20 September 2008 / Published: 25 September 2008
Cited by 9 | PDF Full-text (440 KB) | HTML Full-text | XML Full-text
Abstract
In this study measurements of color parameters of UHT milk were performed, by using a MOM-color 100 photoelectric tristimulus colorimeter. Colors of UHT milk samples containing 3.2% and 1.6% milk fat, processed under industrial conditions, packed in polyethylene terephtalate (PET) based packages, and stored for 0, 15, 30, 45, 60 and 90 days at ambient temperature (20±5°C) were examined. Results are shown in four different systems that define measurement of color parameters expressed in: CIE, CIE L*a*b*, Hünter and ANLAB – Adams Nickerson systems. Average value of mean reflectance of UHT milk determined in CIE system statistically is highly significantly changed, (p < 0.01) depending on duration of storaging, percentage of milk fat, as well as on the interaction of the mentioned factors. For the UHT milk with 1.6% milk fat statistically significant (p < 0.05) decrease of psychometric chroma b* occurs after 60 days, and for milk with 3.2% milk fat established on 45th day of storage. Full article
Open AccessArticle Integrated Evaluation of Urban Development Suitability Based on Remote Sensing and GIS Techniques – A Case Study in Jingjinji Area, China
Sensors 2008, 8(9), 5975-5986; doi:10.3390/s8095975
Received: 27 July 2008 / Revised: 15 September 2008 / Accepted: 20 September 2008 / Published: 25 September 2008
Cited by 19 | PDF Full-text (220 KB) | HTML Full-text | XML Full-text | Correction | Supplementary Files
Abstract
Jingjinji area (namely Beijing, Tianjin and He Bei Province) is one of the three largest regional economic communities in China. Urban expansion has sped up in the past 20 years in this area due to the rapid economic and population growth. Evaluating [...] Read more.
Jingjinji area (namely Beijing, Tianjin and He Bei Province) is one of the three largest regional economic communities in China. Urban expansion has sped up in the past 20 years in this area due to the rapid economic and population growth. Evaluating the landuse suitability for urban growth on a regional scale is an urgent need, because the most suitable areas and the most suitable scale of urban growth can thus be determined accordingly. In order to meet this requirement, remote sensing and geographic information system (GIS) techniques were adopted, and an integrated evaluating model was developed supported by AHP method. The integrated urban development suitability index (UDSI) was calculated using this model. According to the UDSI result, the spatial distribution of urban development suitability and its driving forces were analyzed. Urban boundaries in 1995, 2000 and 2005, which were derived from Landsat TM/ETM+ satellite data, were overlaid on the UDSI map, and the suitable urban develop tendency in this area were discussed. The result of this study indicated that integrated evaluation of urban development could be conducted in an operational way using remote sensing data, GIS spatial analysis technique and AHP modeling method. Full article
(This article belongs to the Special Issue Sensors for Urban Environmental Monitoring)
Open AccessArticle Electrochemical Assay of Human Islet Amyloid Polypeptide and Its Aggregation
Sensors 2008, 8(9), 5987-5995; doi:10.3390/s8095987
Received: 14 August 2008 / Revised: 11 September 2008 / Accepted: 22 September 2008 / Published: 25 September 2008
Cited by 7 | PDF Full-text (120 KB) | HTML Full-text | XML Full-text
Abstract
Square wave voltammetry is used in this work to detect human islet amyloid polypeptide (hIAPP) by using the oxidized signal of the tyrosine residue in hIAPP. A detection limit of 1×10-6 M for hIAPP has been obtained. A kinetic study of [...] Read more.
Square wave voltammetry is used in this work to detect human islet amyloid polypeptide (hIAPP) by using the oxidized signal of the tyrosine residue in hIAPP. A detection limit of 1×10-6 M for hIAPP has been obtained. A kinetic study of the aggregation process has been carried out according to the relationship between the anodic peak current in the square wave voltammograms of hIAPP and the incubation period. The results show that the nucleation starts in the first hour of incubation and then, during the next two hours, aggregation may occur rapidly. hIAPP can therefore be monitored with a label-free electrochemical method with low detection limit and high sensitivity. This electrochemical method can be also utilized to study the kinetics of hIAPP aggregation, and it may be also employed to study the conformational changes of the polypeptide. Full article
Open AccessArticle Programming an Artificial Neural Network Tool for Spatial Interpolation in GIS - A Case Study for Indoor Radio Wave Propagation of WLAN
Sensors 2008, 8(9), 5996-6014; doi:10.3390/s8095996
Received: 31 July 2008 / Revised: 3 September 2008 / Accepted: 11 September 2008 / Published: 25 September 2008
Cited by 6 | PDF Full-text (536 KB) | HTML Full-text | XML Full-text
Abstract
Wireless communication networks offer subscribers the possibilities of free mobility and access to information anywhere at any time. Therefore, electromagnetic coverage calculations are important for wireless mobile communication systems, especially in Wireless Local Area Networks (WLANs). Before any propagation computation is performed, [...] Read more.
Wireless communication networks offer subscribers the possibilities of free mobility and access to information anywhere at any time. Therefore, electromagnetic coverage calculations are important for wireless mobile communication systems, especially in Wireless Local Area Networks (WLANs). Before any propagation computation is performed, modeling of indoor radio wave propagation needs accurate geographical information in order to avoid the interruption of data transmissions. Geographic Information Systems (GIS) and spatial interpolation techniques are very efficient for performing indoor radio wave propagation modeling. This paper describes the spatial interpolation of electromagnetic field measurements using a feed-forward back-propagation neural network programmed as a tool in GIS. The accuracy of Artificial Neural Networks (ANN) and geostatistical Kriging were compared by adjusting procedures. The feedforward back-propagation ANN provides adequate accuracy for spatial interpolation, but the predictions of Kriging interpolation are more accurate than the selected ANN. The proposed GIS ensures indoor radio wave propagation model and electromagnetic coverage, the number, position and transmitter power of access points and electromagnetic radiation level. Pollution analysis in a given propagation environment was done and it was demonstrated that WLAN (2.4 GHz) electromagnetic coverage does not lead to any electromagnetic pollution due to the low power levels used. Example interpolated electromagnetic field values for WLAN system in a building of Yildiz Technical University, Turkey, were generated using the selected network architectures to illustrate the results with an ANN. Full article
Open AccessArticle Fabrication of a Novel Conductometric Biosensor for Detecting Mycobacterium avium subsp. paratuberculosis Antibodies
Sensors 2008, 8(9), 6015-6025; doi:10.3390/s8096015
Received: 2 September 2008 / Revised: 18 September 2008 / Accepted: 22 September 2008 / Published: 26 September 2008
Cited by 9 | PDF Full-text (89 KB) | HTML Full-text | XML Full-text
Abstract
Johne’s disease (JD) is one of the most costly bacterial diseases in cattle. In the U.S., economic losses from the disease have been estimated to exceed $1,500,000,000 per year, mainly from the effects of reduced milk production. Current diagnostic tests for JD [...] Read more.
Johne’s disease (JD) is one of the most costly bacterial diseases in cattle. In the U.S., economic losses from the disease have been estimated to exceed $1,500,000,000 per year, mainly from the effects of reduced milk production. Current diagnostic tests for JD are laboratory based and many of those tests require specialized equipment and training. Development of rapid and inexpensive diagnostic assays, which are adapted for point-ofcare applications, would aid in the control of JD. In this study, a polyaniline (Pani)-based conductometric biosensor, in an immunomigration format, was fabricated for the detection of serum antibody (IgG) against the causal organism of JD, Mycobacterium avium subsp. paratuberculosis (MAP). Immobilized Mycobacterium avium purified proteins in the capture membrane were used to detect MAP IgG, previously bound with Pani/anti-bovine IgG* conjugate in the conjugate membrane. After detection, the Pani in the sandwiched captured complex bridges an electrical circuit between the silver electrodes, flanking the capture membrane. The electrical conductance, caused by Pani, was measured as drop in electrical resistance. Testing of the biosensor with known JD positive and negative serum samples demonstrated a significant difference in the mean resistance observed between the groups. This proof-of-concept study demonstrated that a conductometric biosensor could detect MAP IgG in 2 minutes. The biosensor’s speed of detection and the equipment involved would, among other things, support its application towards the various point-ofcare opportunities aimed at JD management and control. Full article
(This article belongs to the Special Issue Biosensors for Point-of-Care Applications)
Open AccessArticle Surface Heat Balance Analysis of Tainan City on March 6, 2001 Using ASTER and Formosat-2 Data
Sensors 2008, 8(9), 6026-6044; doi:10.3390/s8096026
Received: 1 September 2008 / Revised: 18 September 2008 / Accepted: 24 September 2008 / Published: 26 September 2008
Cited by 9 | PDF Full-text (2862 KB) | HTML Full-text | XML Full-text
Abstract
The urban heat island phenomenon occurs as a mixed result of anthropogenic heat discharge, decreased vegetation, and increased artificial impervious surfaces. To clarify the contribution of each factor to the urban heat island, it is necessary to evaluate the surface heat balance. [...] Read more.
The urban heat island phenomenon occurs as a mixed result of anthropogenic heat discharge, decreased vegetation, and increased artificial impervious surfaces. To clarify the contribution of each factor to the urban heat island, it is necessary to evaluate the surface heat balance. Satellite remote sensing data of Tainan City, Taiwan, obtained from Terra ASTER and Formosat-2 were used to estimate surface heat balance in this study. ASTER data is suitable for analyzing heat balance because of the wide spectral range. We used Formosat-2 multispectral data to classify the land surface, which was used to interpolate some surface parameters for estimating heat fluxes. Because of the high spatial resolution of the Formosat-2 image, more roads, open spaces and small vegetation areas could be distinguished from buildings in urban areas; however, misclassifications of land cover in such areas using ASTER data would overestimate the sensible heat flux. On the other hand, the small vegetated areas detected from the Formosat-2 image slightly increased the estimation of latent heat flux. As a result, the storage heat flux derived from Formosat-2 is higher than that derived from ASTER data in most areas. From these results, we can conclude that the higher resolution land coverage map increases accuracy of the heat balance analysis. Storage heat flux occupies about 60 to 80% of the net radiation in most of the artificial surface areas in spite of their usages. Because of the homogeneity of the building roof materials, there is no contrast between the storage heat flux in business and residential areas. In sparsely vegetated urban areas, more heat is stored and latent heat is smaller than that in the forested suburbs. This result implies that density of vegetation has a significant influence in decreasing temperatures. Full article
(This article belongs to the Special Issue Sensors for Urban Environmental Monitoring)
Open AccessArticle An Evaluation of Radarsat-1 and ASTER Data for Mapping Veredas (Palm Swamps)
Sensors 2008, 8(9), 6055-6076; doi:10.3390/s8096055
Received: 6 August 2008 / Revised: 10 September 2008 / Accepted: 22 September 2008 / Published: 26 September 2008
Cited by 6 | PDF Full-text (913 KB) | HTML Full-text | XML Full-text
Abstract
Veredas (palm swamps) are wetland complexes associated with the Brazilian savanna (cerrado) that often represent the only available source of water for the ecosystem during the dry months. Their extent and condition are mainly unknown and their cartography is an [...] Read more.
Veredas (palm swamps) are wetland complexes associated with the Brazilian savanna (cerrado) that often represent the only available source of water for the ecosystem during the dry months. Their extent and condition are mainly unknown and their cartography is an essential issue for their protection. This research article evaluates some of the fine resolution satellite data both in the radar (Radarsat-1) and optical domain (ASTER) for the delineation and characterization of veredas. Two separate approaches are evaluated. First, given the known potential of Radarsat-1 images for wetland inventories, the automatic delineation of veredas is tested using only Radarsat-1 data and a Markov random fields region-based segmentation. In this case, to increase performance, processing is limited to a buffer zone around the river network. Then, characterization of their type is attempted using traditional classification methods of ASTER optical data combined with Radarsat-1 data. The automatic classification of Radarsat data yielded results with an overall accuracy between 62 and 69%, that proved reliable enough for delineating wide and very humid veredas. Scenes from the wet season and with a smaller angle of incidence systematically yielded better results. For the classification of the main vegetation types, better results (overall success of 78.8%) were obtained by using only the visible and near infrared (VNIR) bands of the ASTER image. Radarsat data did not bring any improvement to these classification results. In fact, when using solely the Radarsat data from two different angle of incidence and two different dates, the classification results were low (50.8%) but remained powerful for delineating the permanently moist riparian forest portion of the veredas with an accuracy better than 75% in most cases. These results are considered good given the width of some types often less than 50 m wide compared with the resolution of the images (12.5 - 15 m). Comparing the classification results with the Radarsat-generated delineation allows an understanding of the relation between synthetic aperture radar (SAR) backscattering and vegetation types of the veredas. Full article
(This article belongs to the Special Issue Synthetic Aperture Radar (SAR))
Open AccessArticle Spectral-Based Blind Image Restoration Method for Thin TOMBO Imagers
Sensors 2008, 8(9), 6108-6124; doi:10.3390/s8096108
Received: 1 July 2008 / Revised: 7 September 2008 / Accepted: 8 September 2008 / Published: 26 September 2008
Cited by 8 | PDF Full-text (733 KB) | HTML Full-text | XML Full-text
Abstract
With the recent advances in microelectronic fabrication technology, it becomes now possible to fabricate thin imagers, less than half a millimeter thick. Dubbed TOMBO (an acronym for thin observation module by bound optics), a thin camera-on-a-chip integrates micro-optics and photo-sensing elements, together [...] Read more.
With the recent advances in microelectronic fabrication technology, it becomes now possible to fabricate thin imagers, less than half a millimeter thick. Dubbed TOMBO (an acronym for thin observation module by bound optics), a thin camera-on-a-chip integrates micro-optics and photo-sensing elements, together with advanced processing circuitry, all on a single silicon chip. Modeled after the compound-eye found in insects and many other arthropods, the TOMBO imager captures simultaneously a mosaic of low resolution images. In this paper, we describe and analyze a novel spectral-based blind algorithm that enables the restoration of a high resolution image from the captured low resolution images.The proposed blind restoration method does not require prior information about the imaging system nor the original scene. Furthermore, it alleviates the need for conventional de-shading and rearrangement processing techniques. Experimental results demonstrate that the proposed method can restore images for SNER lower than 3dB. Full article
(This article belongs to the Special Issue Integrated High-performance Imagers)

Review

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Open AccessReview Extended Calix[4]arene-Based Receptors for Molecular Recognition and Sensing
Sensors 2008, 8(9), 5313-5335; doi:10.3390/s8095313
Received: 1 July 2008 / Revised: 28 August 2008 / Accepted: 29 August 2008 / Published: 1 September 2008
Cited by 27 | PDF Full-text (1391 KB) | HTML Full-text | XML Full-text
Abstract
Recent advances in the area of recognition and sensing have shown that artificial receptors derived from extended calix[4]arenes bearing multiple π-conjugated fluorophoric or chromophoric systems have found useful to enhance binding affinity, selectivity and sensitivity for recognition and sensing of a targeted [...] Read more.
Recent advances in the area of recognition and sensing have shown that artificial receptors derived from extended calix[4]arenes bearing multiple π-conjugated fluorophoric or chromophoric systems have found useful to enhance binding affinity, selectivity and sensitivity for recognition and sensing of a targeted ion or molecule. A comprehensive review of various π-conjugation-extended calyx[4]arene-based receptors with the highlight on the design and binding characterization for recognition and sensing is presented. Full article
(This article belongs to the Special Issue Molecular Recognition and Sensors, Including Molecular Imprinting)
Open AccessReview Atmospheric Effects on InSAR Measurements and Their Mitigation
Sensors 2008, 8(9), 5426-5448; doi:10.3390/s8095426
Received: 28 July 2008 / Revised: 29 August 2008 / Accepted: 29 August 2008 / Published: 3 September 2008
Cited by 60 | PDF Full-text (1695 KB) | HTML Full-text | XML Full-text
Abstract
Interferometric Synthetic Aperture Radar (InSAR) is a powerful technology for observing the Earth surface, especially for mapping the Earth's topography and deformations. InSAR measurements are however often significantly affected by the atmosphere as the radar signals propagate through the atmosphere whose state [...] Read more.
Interferometric Synthetic Aperture Radar (InSAR) is a powerful technology for observing the Earth surface, especially for mapping the Earth's topography and deformations. InSAR measurements are however often significantly affected by the atmosphere as the radar signals propagate through the atmosphere whose state varies both in space and in time. Great efforts have been made in recent years to better understand the properties of the atmospheric effects and to develop methods for mitigating the effects. This paper provides a systematic review of the work carried out in this area. The basic principles of atmospheric effects on repeat-pass InSAR are first introduced. The studies on the properties of the atmospheric effects, including the magnitudes of the effects determined in the various parts of the world, the spectra of the atmospheric effects, the isotropic properties and the statistical distributions of the effects, are then discussed. The various methods developed for mitigating the atmospheric effects are then reviewed, including the methods that are based on PSInSAR processing, the methods that are based on interferogram modeling, and those that are based on external data such as GPS observations, ground meteorological data, and satellite data including those from the MODIS and MERIS. Two examples that use MODIS and MERIS data respectively to calibrate atmospheric effects on InSAR are also given. Full article
(This article belongs to the Special Issue Synthetic Aperture Radar (SAR))
Open AccessReview Over-the-Counter Biosensors: Past, Present, and Future
Sensors 2008, 8(9), 5535-5559; doi:10.3390/s8095535
Received: 19 August 2008 / Revised: 28 August 2008 / Accepted: 3 September 2008 / Published: 6 September 2008
Cited by 50 | PDF Full-text (595 KB) | HTML Full-text | XML Full-text
Abstract
The demand for specific, low cost, rapid, sensitive and easy detection of biomolecules is huge. A well-known example is the glucose meters used by diabetics to monitor their blood glucose levels. Nowadays, a vast majority of the glucose meters are based on [...] Read more.
The demand for specific, low cost, rapid, sensitive and easy detection of biomolecules is huge. A well-known example is the glucose meters used by diabetics to monitor their blood glucose levels. Nowadays, a vast majority of the glucose meters are based on electrochemical biosensor technology. The inherent small size and simple construction of the electrochemical transducer and instrument are ideally suited for pointof-care biosensing. Besides glucose, a wide variety of electrochemical biosensors have been developed for the measurements of some other key metabolites, proteins, and nucleic acids. Nevertheless, unlike the glucose meters, limited success has been achieved for the commercialization of the protein and nucleic acid biosensors. In this review article, key technologies on the electrochemical detection of key metabolites, proteins, and DNAs are discussed in detail, with particular emphasis on those that are compatible to home-use setting. Moreover, emerging technologies of lab-on-a-chip microdevices and nanosensors (i.e., silicon and carbon nanotube field-effect sensors) offer opportunities for the construction of new generation biosensors with much better performances. Together with the continuous innovations in the basic components of biosensors (i.e., transducers, biorecognition molecules, immobilization and signal transduction schemes), consumers could soon buy different kinds of biosensing devices in the pharmacy stores. Full article
(This article belongs to the Special Issue Biosensors for Point-of-Care Applications)
Open AccessReview Thermographic Phosphors for High Temperature Measurements: Principles, Current State of the Art and Recent Applications
Sensors 2008, 8(9), 5673-5744; doi:10.3390/s8095673
Received: 25 July 2008 / Revised: 1 September 2008 / Accepted: 5 September 2008 / Published: 15 September 2008
Cited by 110 | PDF Full-text (2728 KB) | HTML Full-text | XML Full-text
Abstract
This paper reviews the state of phosphor thermometry, focusing on developments in the past 15 years. The fundamental principles and theory are presented, and the various spectral and temporal modes, including the lifetime decay, rise time and intensity ratio, are discussed. The [...] Read more.
This paper reviews the state of phosphor thermometry, focusing on developments in the past 15 years. The fundamental principles and theory are presented, and the various spectral and temporal modes, including the lifetime decay, rise time and intensity ratio, are discussed. The entire phosphor measurement system, including relative advantages to conventional methods, choice of phosphors, bonding techniques, excitation sources and emission detection, is reviewed. Special attention is given to issues that may arise at high temperatures. A number of recent developments and applications are surveyed, with examples including: measurements in engines, hypersonic wind tunnel experiments, pyrolysis studies and droplet/spray/gas temperature determination. They show the technique is flexible and successful in measuring temperatures where conventional methods may prove to be unsuitable. Full article
(This article belongs to the Special Issue Aerospace Sensor Systems)
Open AccessReview Developments and Applications of Electrogenerated Chemiluminescence Sensors Based on Micro- and Nanomaterials
Sensors 2008, 8(9), 5942-5960; doi:10.3390/s8095942
Received: 11 August 2008 / Revised: 22 September 2008 / Accepted: 23 September 2008 / Published: 25 September 2008
Cited by 13 | PDF Full-text (197 KB) | HTML Full-text | XML Full-text
Abstract
A variety of recent developments and applications of electrogenerated chemiluminescence (ECL) for sensors are described. While tris(2,2′-bipyridyl)-ruthenium(II) and luminol have dominated and continue to pervade the field of ECL-based sensors, recent work has focused on use of these lumophores with micro- and [...] Read more.
A variety of recent developments and applications of electrogenerated chemiluminescence (ECL) for sensors are described. While tris(2,2′-bipyridyl)-ruthenium(II) and luminol have dominated and continue to pervade the field of ECL-based sensors, recent work has focused on use of these lumophores with micro- and nanomaterials. It has also extended to inherently luminescent nanomaterials, such as quantum dots. Sensor configurations including microelectrode arrays and microfluidics are reviewed and, with the recent trend toward increased use of nanomaterials, special attention has been given to sensors which include thin films, nanoparticles and nanotubes. Applications of ECL labels and examples of label-free sensing that incorporate nanomaterials are also discussed. Full article
Open AccessReview Sensors and Biosensors for the Determination of Small Molecule Biological Toxins
Sensors 2008, 8(9), 6045-6054; doi:10.3390/s8096045
Received: 19 July 2008 / Revised: 3 September 2008 / Accepted: 5 September 2008 / Published: 26 September 2008
Cited by 29 | PDF Full-text (76 KB) | HTML Full-text | XML Full-text
Abstract
The following review of sensors and biosensors focuses on the determination of commonly studied small molecule biological toxins, including mycotoxins and small molecule neurotoxins. Because of the high toxicity of small molecule toxins, an effective analysis technique for determining their toxicity is [...] Read more.
The following review of sensors and biosensors focuses on the determination of commonly studied small molecule biological toxins, including mycotoxins and small molecule neurotoxins. Because of the high toxicity of small molecule toxins, an effective analysis technique for determining their toxicity is indispensable. Sensors and biosensors have emerged as sensitive and rapid techniques for toxicity analysis in the past decade. Several different sensors for the determination of mycotoxins and other small molecule neurotoxins have been reported in the literature, and many of these sensors such as tissue biosensors, enzyme sensors, optical immunosensors, electrochemical sensors, quartz crystal sensors, and surface plasmon resonance biosensors are reviewed in this paper. Sensors are a practical and convenient monitoring tool in the area of routine analysis, and their specificity, sensitivity, reproducibility and analysis stability should all be improved in future work. In addition, accuracy field portable sensing devices and multiplexing analysis devices will be important requirement for the future. Full article
(This article belongs to the Special Issue Toxin Sensors)
Open AccessReview BioMEMS –Advancing the Frontiers of Medicine
Sensors 2008, 8(9), 6077-6107; doi:10.3390/s8096077
Received: 28 August 2008 / Revised: 16 September 2008 / Accepted: 24 September 2008 / Published: 26 September 2008
Cited by 24 | PDF Full-text (549 KB) | HTML Full-text | XML Full-text
Abstract
Biological and medical application of micro-electro-mechanical-systems (MEMS) is currently seen as an area of high potential impact. Integration of biology and microtechnology has resulted in the development of a number of platforms for improving biomedical and pharmaceutical technologies. This review provides a [...] Read more.
Biological and medical application of micro-electro-mechanical-systems (MEMS) is currently seen as an area of high potential impact. Integration of biology and microtechnology has resulted in the development of a number of platforms for improving biomedical and pharmaceutical technologies. This review provides a general overview of the applications and the opportunities presented by MEMS in medicine by classifying these platforms according to their applications in the medical field. Full article
(This article belongs to the Special Issue BioMEMS)

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