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Sensors, Volume 7, Issue 1 (January 2007), Pages 1-156

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Research

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Open AccessArticle Determination of Critical Conditions for the Formation of Electrodeposited Copper Structures Suitable for Electrodes in Electrochemical Devices
Sensors 2007, 7(1), 1-15; doi:10.3390/s7010001
Received: 27 October 2006 / Revised: 12 December 2006 / Accepted: 15 December 2006 / Published: 1 January 2007
Cited by 36 | PDF Full-text (1521 KB) | HTML Full-text | XML Full-text
Abstract
Electrodeposition of copper from acid sulfate solutions at overpotentials on theplateau of the limiting diffusion current density and at higher overpotentials wasexamined. The average current efficiencies for hydrogen evolution reaction aredetermined by a measurement of the quantity of evolved hydrogen and the overallelectrodeposition
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Electrodeposition of copper from acid sulfate solutions at overpotentials on theplateau of the limiting diffusion current density and at higher overpotentials wasexamined. The average current efficiencies for hydrogen evolution reaction aredetermined by a measurement of the quantity of evolved hydrogen and the overallelectrodeposition current as a function of electrodeposition time, while morphologies ofcopper deposits are examined by the use of the scanning electron microscopy (SEM)technique. It is found that the open and porous structures of copper deposits (denoted andas honeycomb – like copper structures), suitable for electrodes in electrochemical devicessuch as fuel cells and chemical sensors, were reached by electrodeposition processesfrom solutions with the lower concentrations of Cu (II) ions (0.15 M CuSO4 and less in0.50 M H2SO4) at overpotentials outside the plateau of the limiting diffusion currentdensity at which the quantity of evolved hydrogen was enough to change hydrodynamicconditions in the near – electrode layer. The main characteristics of these copperstructures were craters or holes formed primarily due to the attachment hydrogen bubbleswith agglomerates of copper grains between them. Full article
Open AccessArticle Asymptotic Effectiveness of the Event-Based Sampling According to the Integral Criterion
Sensors 2007, 7(1), 16-37; doi:10.3390/s7010016
Received: 10 August 2006 / Accepted: 5 January 2007 / Published: 6 January 2007
Cited by 37 | PDF Full-text (173 KB) | HTML Full-text | XML Full-text
Abstract
A rapid progress in intelligent sensing technology creates new interest in a development of analysis and design of non-conventional sampling schemes. The investigation of the event-based sampling according to the integral criterion is presented in this paper. The investigated sampling scheme is an
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A rapid progress in intelligent sensing technology creates new interest in a development of analysis and design of non-conventional sampling schemes. The investigation of the event-based sampling according to the integral criterion is presented in this paper. The investigated sampling scheme is an extension of the pure linear send-on- delta/level-crossing algorithm utilized for reporting the state of objects monitored by intelligent sensors. The motivation of using the event-based integral sampling is outlined. The related works in adaptive sampling are summarized. The analytical closed-form formulas for the evaluation of the mean rate of event-based traffic, and the asymptotic integral sampling effectiveness, are derived. The simulation results verifying the analytical formulas are reported. The effectiveness of the integral sampling is compared with the related linear send-on-delta/level-crossing scheme. The calculation of the asymptotic effectiveness for common signals, which model the state evolution of dynamic systems in time, is exemplified. Full article
(This article belongs to the Special Issue Intelligent Sensors)
Open AccessArticle Improvement of Bioactive Compound Classification through Integration of Orthogonal Cell-Based Biosensing Methods
Sensors 2007, 7(1), 38-51; doi:10.3390/s7010038
Received: 14 December 2006 / Accepted: 18 January 2007 / Published: 21 January 2007
Cited by 6 | PDF Full-text (254 KB) | HTML Full-text | XML Full-text
Abstract
Lack of specificity for different classes of chemical and biological agents, and false positives and negatives, can limit the range of applications for cell-based biosensors. This study suggests that the integration of results from algal cells (Mesotaenium caldariorum) and fish chromatophores (Betta splendens)
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Lack of specificity for different classes of chemical and biological agents, and false positives and negatives, can limit the range of applications for cell-based biosensors. This study suggests that the integration of results from algal cells (Mesotaenium caldariorum) and fish chromatophores (Betta splendens) improves classification efficiency and detection reliability. Cells were challenged with paraquat, mercuric chloride, sodium arsenite and clonidine. The two detection systems were independently investigated for classification of the toxin set by performing discriminant analysis. The algal system correctly classified 72% of the bioactive compounds, whereas the fish chromatophore system correctly classified 68%. The combined classification efficiency was 95%. The algal sensor readout is based on fluorescence measurements of changes in the energy producing pathways of photosynthetic cells, whereas the response from fish chromatophores was quantified using optical density. Change in optical density reflects interference with the functioning of cellular signal transduction networks. Thus, algal cells and fish chromatophores respond to the challenge agents through sufficiently different mechanisms of action to be considered orthogonal. Full article
Open AccessArticle A Non-invasive and Real-time Monitoring of the Regulation of Photosynthetic Metabolism Biosensor Based on Measurement of Delayed Fluorescence in Vivo
Sensors 2007, 7(1), 52-66; doi:10.3390/s7010052
Received: 12 November 2006 / Accepted: 17 January 2007 / Published: 24 January 2007
Cited by 11 | PDF Full-text (107 KB) | HTML Full-text | XML Full-text
Abstract
In this paper, a new principle biosensor for non-invasive monitoring of theregulation of photosynthetic metabolism based on quantitative measurement of delayedfluorescence (DF) is developed. The biosensor, which uses light-emitting diode lattice asexcitation light source and a compact Single Photon Counting Module to collect
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In this paper, a new principle biosensor for non-invasive monitoring of theregulation of photosynthetic metabolism based on quantitative measurement of delayedfluorescence (DF) is developed. The biosensor, which uses light-emitting diode lattice asexcitation light source and a compact Single Photon Counting Module to collect DF signal,is portable and can evaluate plant photosynthesis capacity in vivo. Compared with itsprimary version in our previous report, the biosensor can better control environmentalfactors. Moreover, the improved biosensor can automatically complete the measurements oflight and CO2 response curves of DF intensity. In the experimental study, the testing of theimproved biosensor has been made in soybean (Glycine max Zaoshu No. 18) seedlingstreated with NaHSO3 to induce changes in seedlings growth and photosynthetic metabolism.Contrast evaluations of seedlings photosynthesis were made from measurements of netphotosynthesis rate (Pn) based on consumption of CO2 in tested plants. Current testingresults have demonstrated that the improved biosensor can accurately determine theregulatory effects of NaHSO3 on photosynthetic metabolism. Therefore, the biosensorpresented here could be potential useful for real-time monitoring the regulatory effects ofplant growth regulators (PGRs) and other exogenous chemical factors on plant growth andphotosynthetic metabolism. Full article
(This article belongs to the Special Issue Physiological Sensing)
Open AccessArticle Influence of Different Genotypes on Trypsin Inhibitor Levels and Activity in Soybeans
Sensors 2007, 7(1), 67-74; doi:10.3390/s7010067
Received: 30 November 2006 / Accepted: 10 January 2007 / Published: 24 January 2007
Cited by 5 | PDF Full-text (195 KB) | HTML Full-text | XML Full-text
Abstract
This study describes the relationship between the two major trypsin inhibitors (TI) in soybean, i.e., the Kunitz (KTI) and Bowman-Birk (BBI) trypsin inhibitors, as well as between them and the corresponding trypsin inhibitor activity (TIA). Twelve investigated soybean genotypes showed significant differences in
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This study describes the relationship between the two major trypsin inhibitors (TI) in soybean, i.e., the Kunitz (KTI) and Bowman-Birk (BBI) trypsin inhibitors, as well as between them and the corresponding trypsin inhibitor activity (TIA). Twelve investigated soybean genotypes showed significant differences in TI levels and TIA. A very strong positive correlation was found between the levels of KTI and total BBI (r = 0.94, P < 0.05). No relationship was found between KTI, BBI or total TI and TIA. Based on this data, it appears that the levels of major TI in soybean are related. Understanding the relationship between trypsin inhibitors and their activities could be useful for further improvement of the health impacts of soy proteins. Full article
Open AccessArticle E.M.I Effects of Cathodic Protection on Electromagnetic Flowmeters
Sensors 2007, 7(1), 75-83; doi:10.3390/s7010075
Received: 8 August 2006 / Accepted: 23 January 2007 / Published: 26 January 2007
Cited by 3 | PDF Full-text (166 KB) | HTML Full-text | XML Full-text
Abstract
Electromagnetic flowmeters are used to measure the speed of water flow in water distribution systems. Corrosion problem in metal pipelines can be solved by cathodic protection methods. This paper presents a research on corruptive effects of the cathodic protection system on electromagnetic flowmeter
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Electromagnetic flowmeters are used to measure the speed of water flow in water distribution systems. Corrosion problem in metal pipelines can be solved by cathodic protection methods. This paper presents a research on corruptive effects of the cathodic protection system on electromagnetic flowmeter depending on its measuring principle. Experimental measurements are realized on the water distribution pipelines of the Izmir Municipality, Department of Water and Drainage Administration (IZSU) in Turkey and measurement results are given. Experimental results proved that the values measured by the electromagnetic flowmeter (EMF) are affected by cathodic protection system current. Comments on the measurement results are made and precautions to be taken are proposed. Full article
(This article belongs to the Special Issue Sensors in Flow Analysis)
Open AccessArticle Calibration of a Sensor Array (an Electronic Tongue) for Identification and Quantification of Odorants from Livestock Buildings
Sensors 2007, 7(1), 103-128; doi:10.3390/s7010103
Received: 10 October 2006 / Accepted: 20 December 2006 / Published: 29 January 2007
Cited by 5 | PDF Full-text (233 KB) | HTML Full-text | XML Full-text
Abstract
This contribution serves a dual purpose. The first purpose was to investigate the possibility of using a sensor array (an electronic tongue) for on-line identification and quantification of key odorants representing a variety of chemical groups at two different acidities, pH 6 and
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This contribution serves a dual purpose. The first purpose was to investigate the possibility of using a sensor array (an electronic tongue) for on-line identification and quantification of key odorants representing a variety of chemical groups at two different acidities, pH 6 and 8. The second purpose was to simplify the electronic tongue by decreasing the number of electrodes from 14, which was the number of electrodes in the prototype. Different electrodes were used for identification and quantification of different key odorants. A total of eight electrodes were sufficient for identification and quantification in micromolar concentrations of the key odorants n-butyrate, ammonium and phenolate in test mixtures also containing iso-valerate, skatole and p-cresolate. The limited number of electrodes decreased the standard deviation and the relative standard deviation of triplicate measurements in comparison with the array comprising 14 electrodes. The electronic tongue was calibrated using 4 different test mixtures, each comprising 50 different combinations of key odorants in triplicates, a total of 600 measurements. Back propagation artificial neural network, partial least square and principal component analysis were used in the data analysis. The results indicate that the electronic tongue has a promising potential as an on- line sensor for odorants absorbed in the bioscrubber used in livestock buildings. Full article
Open AccessArticle Classification of Mixtures of Odorants from Livestock Buildings by a Sensor Array (an Electronic Tongue)
Sensors 2007, 7(1), 129-143; doi:10.3390/s7010129
Received: 10 October 2006 / Accepted: 26 January 2007 / Published: 29 January 2007
Cited by 5 | PDF Full-text (237 KB) | HTML Full-text | XML Full-text
Abstract
An electronic tongue comprising different numbers of electrodes was able to classify test mixtures of key odorants characteristic of bioscrubbers of livestock buildings (n-butyrate, iso-valerate, phenolate, p-cresolate, skatole and ammonium). The classification of model solutions indicates that the electronic tongue has a promising
[...] Read more.
An electronic tongue comprising different numbers of electrodes was able to classify test mixtures of key odorants characteristic of bioscrubbers of livestock buildings (n-butyrate, iso-valerate, phenolate, p-cresolate, skatole and ammonium). The classification of model solutions indicates that the electronic tongue has a promising potential as an on- line sensor for characterization of odorants in livestock buildings. Back propagation artificial neural network was used for classification. The average classification rate was above 80% in all cases. A limited, but sufficient number of electrodes were selected by average classification rate and relative entropy. The sufficient number of electrodes decreased standard deviation and relative standard deviation compared to the full electrode array. Full article
Open AccessArticle An Improved Particle Filter for Target Tracking in Sensor Systems
Sensors 2007, 7(1), 144-156; doi:10.3390/s7010144
Received: 23 December 2006 / Accepted: 27 January 2007 / Published: 29 January 2007
Cited by 38 | PDF Full-text (119 KB) | HTML Full-text | XML Full-text
Abstract
Sensor systems are not always equipped with the ability to track targets. Sudden maneuvers of a target can have a great impact on the sensor system, which will increase the miss rate and rate of false target detection. The use of the generic
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Sensor systems are not always equipped with the ability to track targets. Sudden maneuvers of a target can have a great impact on the sensor system, which will increase the miss rate and rate of false target detection. The use of the generic particle filter (PF) algorithm is well known for target tracking, but it can not overcome the degeneracy of particles and cumulation of estimation errors. In this paper, we propose an improved PF algorithm called PF-RBF. This algorithm uses the radial-basis function network (RBFN) in the sampling step for dynamically constructing the process model from observations and updating the value of each particle. With the RBFN sampling step, PF-RBF can give an accurate proposal distribution and maintain the convergence of a sensor system. Simulation results verify that PF-RBF performs better than the Unscented Kalman Filter (UKF), PF and Unscented Particle Filter (UPF) in both robustness and accuracy whether the observation model used for the sensor system is linear or nonlinear. Moreover, the intrinsic property of PF-RBF determines that, when the particle number exceeds a certain amount, the execution time of PF-RBF is less than UPF. This makes PF-RBF a better candidate for the sensor systems which need many particles for target tracking. Full article
(This article belongs to the Special Issue Intelligent Sensors)

Review

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Open AccessReview A Survey on Optimal Signal Processing Techniques Applied to Improve the Performance of Mechanical Sensors in Automotive Applications
Sensors 2007, 7(1), 84-102; doi:10.3390/s7010084
Received: 14 January 2007 / Accepted: 26 January 2007 / Published: 27 January 2007
Cited by 17 | PDF Full-text (78 KB) | HTML Full-text | XML Full-text
Abstract
In this paper a survey on recent applications of optimal signal processing techniques to improve the performance of mechanical sensors is made. Here, a comparison between classical filters and optimal filters for automotive sensors is made, and the current state of the art
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In this paper a survey on recent applications of optimal signal processing techniques to improve the performance of mechanical sensors is made. Here, a comparison between classical filters and optimal filters for automotive sensors is made, and the current state of the art of the application of robust and optimal control and signal processing techniques to the design of the intelligent (or smart) sensors that today’s cars need is presented through several experimental results that show that the fusion of intelligent sensors and optimal signal processing techniques is the clear way to go. However, the switch between the traditional methods of designing automotive sensors and the new ones cannot be done overnight because there are some open research issues that have to be solved. This paper draws attention to one of the open research issues and tries to arouse researcher’s interest in the fusion of intelligent sensors and optimal signal processing techniques. Full article

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