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Sensors, Volume 9, Issue 3 (March 2009) – 56 articles , Pages 1295-2221

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20 pages, 289 KB  
Article
Determination of Lactoferrin and Immunoglobulin G in Animal Milks by New Immunosensors
by Luigi Campanella, Elisabetta Martini, Manuela Pintore and Mauro Tomassetti
Sensors 2009, 9(3), 2202-2221; https://doi.org/10.3390/s90302202 - 26 Mar 2009
Cited by 37 | Viewed by 14822
Abstract
Two different immunosensors, recently developed for the determination of antibacterial proteins (lactoferrin and immunoglobulin G) in buffalo milk and in other commercial animal milks samples, were used in the present study. The aim was to propose these immunosensor methods for routine control of [...] Read more.
Two different immunosensors, recently developed for the determination of antibacterial proteins (lactoferrin and immunoglobulin G) in buffalo milk and in other commercial animal milks samples, were used in the present study. The aim was to propose these immunosensor methods for routine control of important diet products, such as cow and goat milks, and in particular buffalo milk. To this end we employed two different kinds of immunosensors: one for the analysis of immunoglobulin G (IgG), the other was a new amperometric immunosensor for lactoferrin analysis. Lactoferrin and IgG immunosensors were also used for the determination of lactoferrin and immunoglobulin G in buffalo milk on different days of lactation. Full article
(This article belongs to the Special Issue State-of-the-Art Sensors Technology in Italy)
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15 pages, 1172 KB  
Article
Measurement and Evaluation of Finger Tapping Movements Using Log-linearized Gaussian Mixture Networks
by Keisuke Shima, Toshio Tsuji, Akihiko Kandori, Masaru Yokoe and Saburo Sakoda
Sensors 2009, 9(3), 2187-2201; https://doi.org/10.3390/s90302187 - 26 Mar 2009
Cited by 41 | Viewed by 13808
Abstract
This paper proposes a method to quantitatively measure and evaluate finger tapping movements for the assessment of motor function using log-linearized Gaussian mixture networks (LLGMNs). First, finger tapping movements are measured using magnetic sensors, and eleven indices are computed for evaluation. After standardizing [...] Read more.
This paper proposes a method to quantitatively measure and evaluate finger tapping movements for the assessment of motor function using log-linearized Gaussian mixture networks (LLGMNs). First, finger tapping movements are measured using magnetic sensors, and eleven indices are computed for evaluation. After standardizing these indices based on those of normal subjects, they are input to LLGMNs to assess motor function. Then, motor ability is probabilistically discriminated to determine whether it is normal or not using a classifier combined with the output of multiple LLGMNs based on bagging and entropy. This paper reports on evaluation and discrimination experiments performed on finger tapping movements in 33 Parkinson’s disease (PD) patients and 32 normal elderly subjects. The results showed that the patients could be classified correctly in terms of their impairment status with a high degree of accuracy (average rate: 93:1 § 3:69%) using 12 LLGMNs, which was about 5% higher than the results obtained using a single LLGMN. Full article
(This article belongs to the Special Issue State-of-the-Art Sensors Technology in Japan)
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11 pages, 180 KB  
Article
Development of a Novel, Ultra-rapid Biosensor for the Qualitative Detection of Hepatitis B Virus-associated Antigens and Anti-HBV, Based on “Membrane-engineered” Fibroblast Cells with Virus-Specific Antibodies and Antigens
by Antonios Perdikaris, Nikos Alexandropoulos and Spiridon Kintzios
Sensors 2009, 9(3), 2176-2186; https://doi.org/10.3390/s90302176 - 25 Mar 2009
Cited by 27 | Viewed by 13453
Abstract
A novel miniature cell biosensor detection system for the detection of Hepatis B virus (HBV)-associated antigens and anti-HBV is described. The biosensor is based on “membrane-engineered” Vero fibroblast cells immobilized in an alginate matrix. The membrane-engineering process involved the electroinsertion of anti-HBV specific [...] Read more.
A novel miniature cell biosensor detection system for the detection of Hepatis B virus (HBV)-associated antigens and anti-HBV is described. The biosensor is based on “membrane-engineered” Vero fibroblast cells immobilized in an alginate matrix. The membrane-engineering process involved the electroinsertion of anti-HBV specific antibodies (anti-HBs, anti-HBe) or antigens (HBsAg) in the membranes of the Vero cells. The attachment of a homologous antigen to the electroinserted antibody (or, respectively, of the antibody to the electroinserted antigen) triggered specific changes to the cell membrane potential that were measured by appropriate microelectrodes, according to the principle of the Bioelectric Recognition Assay (BERA). The sensor was used for screening 133 clinical blood serum samples according to a double-blind protocol. Considerably higher sensor responses were observed against HBV-positive samples, compared with responses against negative samples or samples positive for heterologous hepatitis viruses such as Hepatitis C (HCV) virus. Detection of anti-HBs antibodies was made possible by using a biosensor based on immobilized Vero cells bearing the respective antigen (HBsAg). The observed response was rapid (45 sec) and quite reproducible. Fluorescence microscopy observations showed that attachment of HBV particles to cells membrane-engineered with anti-HBs was associated with a decrease of [Ca2+]cyt. The perspectives for using the novel biosensor as a qualitative, rapid screening, high throughput assay for HBV antigens and anti-HBs in clinical samples is discussed. Full article
(This article belongs to the Special Issue Pathogen Sensors)
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14 pages, 1206 KB  
Article
Electromechanical Characteristic Analysis of Passive Matrix Addressing for Grating Light Modulator
by Zhu Jin, Zhiyu Wen, Zhihai Zhang and Shanglian Huang
Sensors 2009, 9(3), 2162-2175; https://doi.org/10.3390/s90302162 - 24 Mar 2009
Cited by 1 | Viewed by 11868
Abstract
AGrating Light Modulator (GLM) based on Micro-Electro-Mechanical Systems (MEMS) is applied in projection display. The operating principle of the GLM is introduced in this paper. The electromechanical characteristic of the passive matrix addressing GLM is studied. It was found that if the spring [...] Read more.
AGrating Light Modulator (GLM) based on Micro-Electro-Mechanical Systems (MEMS) is applied in projection display. The operating principle of the GLM is introduced in this paper. The electromechanical characteristic of the passive matrix addressing GLM is studied. It was found that if the spring constant is larger, both the response frequency and the driving voltage are larger. Theoretical analysis shows that the operating voltage and the pull-in voltage of the GLM are 8.16 and 8.74 V, respectively. When an all-selected pixel in a m×n array is actuated by a voltage V0, the voltages of the half-selected pixel in row and column are V0(m-1)/(m+n-1) and V0(n-1)/(m+n-1), respectively, and the voltage of the non-selected pixel is V0/(m+n-1). Finally, the experimental results indicate that the operating voltage and the pull-in voltage are 7.8 and 8.5V respectively, and the response frequency of the GLM is about 7 kHz. The crosstalk in a 16×16 GLM array is validated by the experiment. These studies provide a theoretical basis for improving the GLM driver. Full article
(This article belongs to the Special Issue Selected Papers from the 1st International Conference of the Chinese Society of Micro/Nano Technology)
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14 pages, 286 KB  
Article
Automatic Exudate Detection from Non-dilated Diabetic Retinopathy Retinal Images Using Fuzzy C-means Clustering
by Akara Sopharak, Bunyarit Uyyanonvara and Sarah Barman
Sensors 2009, 9(3), 2148-2161; https://doi.org/10.3390/s90302148 - 24 Mar 2009
Cited by 211 | Viewed by 19627
Abstract
Exudates are the primary sign of Diabetic Retinopathy. Early detection can potentially reduce the risk of blindness. An automatic method to detect exudates from low-contrast digital images of retinopathy patients with non-dilated pupils using a Fuzzy C-Means (FCM) clustering is proposed. Contrast enhancement [...] Read more.
Exudates are the primary sign of Diabetic Retinopathy. Early detection can potentially reduce the risk of blindness. An automatic method to detect exudates from low-contrast digital images of retinopathy patients with non-dilated pupils using a Fuzzy C-Means (FCM) clustering is proposed. Contrast enhancement preprocessing is applied before four features, namely intensity, standard deviation on intensity, hue and a number of edge pixels, are extracted to supply as input parameters to coarse segmentation using FCM clustering method. The first result is then fine-tuned with morphological techniques. The detection results are validated by comparing with expert ophthalmologists’ hand-drawn ground-truths. Sensitivity, specificity, positive predictive value (PPV), positive likelihood ratio (PLR) and accuracy are used to evaluate overall performance. It is found that the proposed method detects exudates successfully with sensitivity, specificity, PPV, PLR and accuracy of 87.28%, 99.24%, 42.77%, 224.26 and 99.11%, respectively. Full article
(This article belongs to the Section Chemical Sensors)
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14 pages, 166 KB  
Article
EROD and MROD as Markers of Cytochrome P450 1A Activities in Hepatic Microsomes from Entire and Castrated Male Pigs
by Galia Zamaratskaia and Vladimir Zlabek
Sensors 2009, 9(3), 2134-2147; https://doi.org/10.3390/s90302134 - 23 Mar 2009
Cited by 57 | Viewed by 16405
Abstract
In the present study, we characterized the kinetic parameters of 7-ethoxy-resorufin O-deethylation (EROD) and 7-methoxyresorufin O-demethylation (MROD) in hepatic microsomes from entire and castrated male pigs. Validation parameters of an HPLC-based method to analyse EROD and MROD activities are also described. [...] Read more.
In the present study, we characterized the kinetic parameters of 7-ethoxy-resorufin O-deethylation (EROD) and 7-methoxyresorufin O-demethylation (MROD) in hepatic microsomes from entire and castrated male pigs. Validation parameters of an HPLC-based method to analyse EROD and MROD activities are also described. Eadie-Hofstee plot analysis demonstrated a biphasic kinetic of EROD, indicating that at least two forms of cytochrome P450 are involved in this reaction. MROD followed monophasic kinetic, suggesting that a single enzyme, or enzymes with similar affinities, is responsible for the reaction. Inhibitory effects of α-naphthoflavone (ANF), ellipticine and furafylline were studied using microsomes from entire and castrated male pigs. ANF is a known inhibitor of both cytochrome P450 1A1 and 1A2 (CYP1A1 and CYP1A2); the presence of ANF in the incubations resulted in the inhibition of both EROD and MROD activities in porcine liver microsomes. EROD activities in porcine liver microsomes were also inhibited by selective CYP1A1 inhibitor ellipticine, but not by CYP1A2 inhibitor furafylline. MROD activities were strongly inhibited by ellipticine and to a much lesser extent by furafylline. Further studies are needed to evaluate substrate specificities of porcine CYP1A1 and CYP1A2. Full article
(This article belongs to the Special Issue Tissue, Cell and Molecular Bioelectrochemistry - New Trends and Approaches)
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17 pages, 248 KB  
Article
Metabolic Discrimination of Select List Agents by Monitoring Cellular Responses in a Multianalyte Microphysiometer
by Sven E. Eklund, Roy G. Thompson, Rachel M. Snider, Clare K. Carney, David W. Wright, John Wikswo and David E. Cliffel
Sensors 2009, 9(3), 2117-2133; https://doi.org/10.3390/s90302117 - 23 Mar 2009
Cited by 38 | Viewed by 16145
Abstract
Harnessing the potential of cells as complex biosensors promises the potential to create sensitive and selective detectors for discrimination of biodefense agents. Here we present toxin detection and suggest discrimination using cells in a multianalyte microphysiometer (MMP) that is capable of simultaneously measuring [...] Read more.
Harnessing the potential of cells as complex biosensors promises the potential to create sensitive and selective detectors for discrimination of biodefense agents. Here we present toxin detection and suggest discrimination using cells in a multianalyte microphysiometer (MMP) that is capable of simultaneously measuring flux changes in four extracellular analytes (acidification rate, glucose uptake, oxygen uptake, and lactate production) in real-time. Differential short-term cellular responses were observed between botulinum neurotoxin A and ricin toxin with neuroblastoma cells, alamethicin and anthrax protective antigen with RAW macrophages, and cholera toxin, muscarine, 2,4-dinitro-phenol, and NaF with CHO cells. These results and the post exposure dynamics and metabolic recovery observed in each case suggest the usefulness of cell-based detectors to discriminate between specific analytes and classes of compounds in a complex matrix, and furthermore to make metabolic inferences on the cellular effects of the agents. This may be particularly valuable for classifying unknown toxins. Full article
(This article belongs to the Special Issue Toxin Sensors)
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29 pages, 367 KB  
Article
Availability and End-to-end Reliability in Low Duty Cycle MultihopWireless Sensor Networks
by Jukka Suhonen, Timo D. Hämäläinen and Marko Hännikäinen
Sensors 2009, 9(3), 2088-2116; https://doi.org/10.3390/s90302088 - 20 Mar 2009
Cited by 25 | Viewed by 16828
Abstract
A wireless sensor network (WSN) is an ad-hoc technology that may even consist of thousands of nodes, which necessitates autonomic, self-organizing and multihop operations. A typical WSN node is battery powered, which makes the network lifetime the primary concern. The highest energy efficiency [...] Read more.
A wireless sensor network (WSN) is an ad-hoc technology that may even consist of thousands of nodes, which necessitates autonomic, self-organizing and multihop operations. A typical WSN node is battery powered, which makes the network lifetime the primary concern. The highest energy efficiency is achieved with low duty cycle operation, however, this alone is not enough. WSNs are deployed for different uses, each requiring acceptable Quality of Service (QoS). Due to the unique characteristics of WSNs, such as dynamic wireless multihop routing and resource constraints, the legacy QoS metrics are not feasible as such. We give a new definition to measure and implement QoS in low duty cycle WSNs, namely availability and reliability. Then, we analyze the effect of duty cycling for reaching the availability and reliability. The results are obtained by simulations with ZigBee and proprietary TUTWSN protocols. Based on the results, we also propose a data forwarding algorithm suitable for resource constrained WSNs that guarantees end-to-end reliability while adding a small overhead that is relative to the packet error rate (PER). The forwarding algorithm guarantees reliability up to 30% PER. Full article
(This article belongs to the Special Issue Wireless Sensor Technologies and Applications)
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12 pages, 190 KB  
Article
Optimization of a PVC Membrane for Reference Field Effect Transistors
by Chao-Sung Lai, Cheng-En Lue, Chia-Ming Yang, Marek Dawgul and Dorota G. Pijanowska
Sensors 2009, 9(3), 2076-2087; https://doi.org/10.3390/s90302076 - 19 Mar 2009
Cited by 9 | Viewed by 13639
Abstract
For the miniaturization of ISFET sensing systems,the concept of a REFET with low ion sensitivity is proposed to replace the conventional reference electrodes through the arrangement of a quasi reference electrode and a differential readout circuit. In this study, an ion-unblocking membrane was [...] Read more.
For the miniaturization of ISFET sensing systems,the concept of a REFET with low ion sensitivity is proposed to replace the conventional reference electrodes through the arrangement of a quasi reference electrode and a differential readout circuit. In this study, an ion-unblocking membrane was used as the top layer of a REFET. To optimize the REFET performance, the influences of the silylating process, different plasticizers, and the composition of the PVC cocktails were investigated. A low sensitivity (10.4 ± 2.2 mV/pH) and high linearity (99.7 ± 0.3 %) in the range from pH 2.2 to pH 11.6 was obtained for the REFET with a 60˚wt.% DNP/(DNP + PVC) membrane. To evaluate the long term stability, the drift coefficient was estimated, and for the best REFET, it was –0.74 mV/h. Two criteria for assessing the lifetime of REFETs were used, namely the increase in pH sensitivity to a value higher than 15 mV/pH and the degradation of linearity below 99 %. For the best REFET, it was approximately 15 days. Full article
(This article belongs to the Section Biosensors)
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14 pages, 647 KB  
Article
Fabrication and Characterization of a Tunable In-plane Resonator with Low Driving Voltage
by Pin-Hsu Kao, Ching-Liang Dai, Cheng-Chih Hsu and Chi-Yuan Lee
Sensors 2009, 9(3), 2062-2075; https://doi.org/10.3390/s90302062 - 18 Mar 2009
Cited by 33 | Viewed by 13600
Abstract
This study presents the fabrication and characterization of a micromechanical tunable in-plane resonator. The resonator is manufactured using the commercial 0.35 µm complementary metal oxide semiconductor (CMOS) process. The resonator is made of aluminum, and the sacrificial layer is silicon dioxide. The post-process [...] Read more.
This study presents the fabrication and characterization of a micromechanical tunable in-plane resonator. The resonator is manufactured using the commercial 0.35 µm complementary metal oxide semiconductor (CMOS) process. The resonator is made of aluminum, and the sacrificial layer is silicon dioxide. The post-process involves only one maskless etching step using an etchant to remove the sacrificial layer. The resonator includes three parts: a driving part to provide a driving force, a sensing part that is used to detect a change in capacitance when the resonator is vibrating, and a tuning part that changes the resonant frequency of the resonator. The main advantages of the tunable resonator are a low driving voltage and compatibility with the CMOS process. The resonant frequency of the resonator can be changed upon applying a dc voltage to the tuning part. To reduce the driving voltage, the driving part is designed as comb-finger rows. Experimental results show that the resonator has a resonant frequency of about 183 kHz and a driving voltage of 10 V; the resonant frequency increases 14 kHz when a tuning voltage of 30 V is applied. The resonator has a maximum frequency–tuning ratio of 7.6%. Full article
(This article belongs to the Special Issue Modeling, Testing and Reliability Issues in MEMS Engineering - 2009)
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27 pages, 825 KB  
Article
Spatial Forecast of Landslides in Three Gorges Based On Spatial Data Mining
by Xianmin Wang and Ruiqing Niu
Sensors 2009, 9(3), 2035-2061; https://doi.org/10.3390/s90302035 - 18 Mar 2009
Cited by 54 | Viewed by 17539
Abstract
The Three Gorges is a region with a very high landslide distribution density and a concentrated population. In Three Gorges there are often landslide disasters, and the potential risk of landslides is tremendous. In this paper, focusing on Three Gorges, which has a [...] Read more.
The Three Gorges is a region with a very high landslide distribution density and a concentrated population. In Three Gorges there are often landslide disasters, and the potential risk of landslides is tremendous. In this paper, focusing on Three Gorges, which has a complicated landform, spatial forecasting of landslides is studied by establishing 20 forecast factors (spectra, texture, vegetation coverage, water level of reservoir, slope structure, engineering rock group, elevation, slope, aspect, etc). China-Brazil Earth Resources Satellite (Cbers) images were adopted based on C4.5 decision tree to mine spatial forecast landslide criteria in Guojiaba Town (Zhigui County) in Three Gorges and based on this knowledge, perform intelligent spatial landslide forecasts for Guojiaba Town. All landslides lie in the dangerous and unstable regions, so the forecast result is good. The method proposed in the paper is compared with seven other methods: IsoData, K-Means, Mahalanobis Distance, Maximum Likelihood, Minimum Distance, Parallelepiped and Information Content Model. The experimental results show that the method proposed in this paper has a high forecast precision, noticeably higher than that of the other seven methods. Full article
(This article belongs to the Special Issue Wireless Sensor Technologies and Applications)
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18 pages, 1281 KB  
Article
GPS Velocity and Strain Rate Fields in Southwest Anatolia from Repeated GPS Measurements
by Saffet Erdoğan, Muhammed Şahin, İbrahim Tiryakioğlu, Engin Gülal and Ali Kazım Telli
Sensors 2009, 9(3), 2017-2034; https://doi.org/10.3390/s90302017 - 17 Mar 2009
Cited by 19 | Viewed by 14063
Abstract
Southwestern Turkey is a tectonically active area. To determine kinematics and strain distribution in this region, a GPS network of sixteen stations was established. We have used GPS velocity field data for southwest Anatolia from continuous measurements covering the period 2003 to 2006 [...] Read more.
Southwestern Turkey is a tectonically active area. To determine kinematics and strain distribution in this region, a GPS network of sixteen stations was established. We have used GPS velocity field data for southwest Anatolia from continuous measurements covering the period 2003 to 2006 to estimate current crustal deformation of this tectonically active region. GPS data were processed using GAMIT/GLOBK software and velocity and strain rate fields were estimated in the study area. The measurements showed velocities of 15-30 mm/yr toward the southwest and strain values up to 0.28-8.23x10-8. Results showed that extension has been determined in the Burdur-Isparta region. In this study, all of strain data reveal an extensional neotectonic regime through the northeast edge of the Isparta Angle despite the previously reported compressional neotectonic regime. Meanwhile, results showed some small differences relatively with the 2006 model of Reilinger et al. As a result, active tectonic movements, in agreement with earthquake fault plane solutions showed important activity. Full article
(This article belongs to the Section Remote Sensors)
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21 pages, 884 KB  
Article
Sensory Properties and Color Measurements of Dietary Chocolates with Different Compositions During Storage for Up to 360 Days
by Jovanka V. Popov-Raljić and Jovanka G. Laličić-Petronijević
Sensors 2009, 9(3), 1996-2016; https://doi.org/10.3390/s90301996 - 17 Mar 2009
Cited by 57 | Viewed by 15582
Abstract
In this work sensory characteristics (appearance – color, brilliance, shape and surface; texture – structure, break, firmness and chewiness; aroma – odor and taste) of dietary chocolates of different compositions were evaluated, in parallel with color parameter measurements. Color was determined instrumentally on [...] Read more.
In this work sensory characteristics (appearance – color, brilliance, shape and surface; texture – structure, break, firmness and chewiness; aroma – odor and taste) of dietary chocolates of different compositions were evaluated, in parallel with color parameter measurements. Color was determined instrumentally on the top and bottom surfaces, using a "MINOLTA" Chroma meter CR 400 thristimulus colorimeter. Sensory evaluation was performed by a group of experienced panelists immediately after the production (0 – 30 days), and then after 90, 180, 270 and 360 days of storage under ambient conditions (t = 18 – 20°C). Results were statistically analyzed by the two-factorial analysis of variance (MANOVA) and with the LSD – test. It was concluded that the storage time up to one year had statistically highly significant (p < 0.01) effects on the sensory attributes of chocolate, as well as on instrumentally measured color parameters. Full article
(This article belongs to the Section Chemical Sensors)
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16 pages, 705 KB  
Article
LULC Classification and Topographic Correction of Landsat-7 ETM+ Imagery in the Yangjia River Watershed: the Influence of DEM Resolution
by Yongnian Gao and Wanchang Zhang
Sensors 2009, 9(3), 1980-1995; https://doi.org/10.3390/s90301980 - 17 Mar 2009
Cited by 49 | Viewed by 15871
Abstract
DEM-based topographic corrections on Landsat-7 ETM+ imagery from rugged terrain, as an effective processing techniques to improve the accuracy of Land Use/Land Cover (LULC) classification as well as land surface parameter retrievals with remotely sensed data, has been frequently reported in the literature. [...] Read more.
DEM-based topographic corrections on Landsat-7 ETM+ imagery from rugged terrain, as an effective processing techniques to improve the accuracy of Land Use/Land Cover (LULC) classification as well as land surface parameter retrievals with remotely sensed data, has been frequently reported in the literature. However, few studies have investigated the exact effects of DEM with different resolutions on the correction of imagery.Taking the topographic corrections on the Landsat-7 ETM+ images acquired from the rugged terrain of the Yangjiahe river basin (P.R. China) as an example, the present work systematically investigates such issues by means of two commonly used topographic correction algorithms with the support of different spatial resolution DEMs. After the pre-processing procedures, i.e. atmospheric correction and geo-registration, were applied to the ETM+ images, two topographic correction algorithms, namely SCS correction and Minnaert correction, were applied to assess the effects of different spatial resolution DEMs obtained from two sources in the removal of topographic effects and LULC classifications. The results suggested that the topographic effects were tremendously reduced with these two algorithms under the support of different spatial resolution DEMs, and the performance of the topographic correction with the 1:50,000-topographic-map DEM was similar to that achieved using SRTM DEM. Moreover, when the same topographic correction algorithm was applied the accuracy of LULC classification after topographic correction based on 1:50,000-topographic-map DEM was similar as that based on SRTM DEM, which implies that the 90 m SRTM DEM can be used as an alternative for the topographic correction of ETM+ imagery when high resolution DEM is unavailable. Full article
(This article belongs to the Section Remote Sensors)
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13 pages, 428 KB  
Article
Implementation of 3D Optical Scanning Technology for Automotive Applications
by Abdil Kuş
Sensors 2009, 9(3), 1967-1979; https://doi.org/10.3390/s90301967 - 17 Mar 2009
Cited by 70 | Viewed by 15871
Abstract
Reverse engineering (RE) is a powerful tool for generating a CAD model from the 3D scan data of a physical part that lacks documentation or has changed from the original CAD design of the part. The process of digitizing a part and creating [...] Read more.
Reverse engineering (RE) is a powerful tool for generating a CAD model from the 3D scan data of a physical part that lacks documentation or has changed from the original CAD design of the part. The process of digitizing a part and creating a CAD model from 3D scan data is less time consuming and provides greater accuracy than manually measuring the part and designing the part from scratch in CAD. 3D optical scanning technology is one of the measurement methods which have evolved over the last few years and it is used in a wide range of areas from industrial applications to art and cultural heritage. It is also used extensively in the automotive industry for applications such as part inspections, scanning of tools without CAD definition, scanning the casting for definition of the stock (i.e. the amount of material to be removed from the surface of the castings) model for CAM programs and reverse engineering. In this study two scanning experiments of automotive applications are illustrated. The first one examines the processes from scanning to re-manufacturing the damaged sheet metal cutting die, using a 3D scanning technique and the second study compares the scanned point clouds data to 3D CAD data for inspection purposes. Furthermore, the deviations of the part holes are determined by using different lenses and scanning parameters. Full article
(This article belongs to the Section Chemical Sensors)
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30 pages, 353 KB  
Article
Vibration and Fluorescence Spectra of Porphyrin- CoredBis(methylol)-propionic Acid Dendrimers
by Boris Minaev and Mikael Lindgren
Sensors 2009, 9(3), 1937-1966; https://doi.org/10.3390/s90301937 - 16 Mar 2009
Cited by 37 | Viewed by 17474
Abstract
Bis-MPA dendron-coated free-base tetraphenylporphyrin and zinc-tetraphenyl-porphyrin (TPPH2 and TPPZn) were studied in comparison with simple porphyrins (H2P, ZnP) by theoretical simulation of their infrared, Raman and electronic absorption spectra, as well as fluorescense emission. Infrared and fluorescence spectra of the [...] Read more.
Bis-MPA dendron-coated free-base tetraphenylporphyrin and zinc-tetraphenyl-porphyrin (TPPH2 and TPPZn) were studied in comparison with simple porphyrins (H2P, ZnP) by theoretical simulation of their infrared, Raman and electronic absorption spectra, as well as fluorescense emission. Infrared and fluorescence spectra of the dendrimers were measured and interpreted along with time-resolved measurements of the fluorescence. The 0-1 emission band of the dendron substituted TPPZn was found to experience a "heavy substitution"-effect. The 0-1 vibronic emission signal is associated with a longer decay time (approx. 7 - 8 ns) than the 0-0 emission (approx. 1 - 1.5 ns). The former contributed with more relative emission yield for larger dendron substituents, in agreement with the appearance of steady-state emission spectra showing increased contribution from the 0-1 vibronic fluorescence band at 650 nm. No such substitution effect was observed in the electronic or vibrational spectra of the substituted free-base variant, TPPH2. Vibration spectra of the parent porphyrins (H2P, ZnP, TPPH2 and TPPZn) were calculated by density functional theory (DFT) using the B3LYP/6-31G** approximation and a detailed analysis of the most active vibration modes was made based on both literature and our own experimental data. Based on the results of theoretical calculations the wide vibronic bands in the visible region were assigned. The vibronic structure also gave a qualitative interpretation of bands in the electronic absorption spectra as well as in fluorescence emission depending on the size of dendrimer substitution. From the results of time-dependent DFT calculations it is suggested that the TPPZn-cored dendrimers indicate strong vibronic interaction and increased Jahn-Teller distortion of the prophyrin core for larger dendrimer generations. Specifically, this leads to the entirely different behaviour of the emission spectra upon substitution of the TPPH2 and TPPZn variants, which was also experimentally observed. Since TPPH2 is originally of lower symmetry the specific distortion upon dendron substitution is not expected to the same extent, which also was in agreement with the experimental findings. Full article
(This article belongs to the Special Issue Dendritic Sensors: From Dendrimer Molecules to Dendritic Cells)
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24 pages, 2130 KB  
Article
Sea Clutter Reduction and Target Enhancement by Neural Networks in a Marine Radar System
by Raúl Vicen-Bueno, Rubén Carrasco-Álvarez, Manuel Rosa-Zurera and José Carlos Nieto-Borge
Sensors 2009, 9(3), 1913-1936; https://doi.org/10.3390/s90301913 - 16 Mar 2009
Cited by 43 | Viewed by 16996
Abstract
The presence of sea clutter in marine radar signals is sometimes not desired. So, efficient radar signal processing techniques are needed to reduce it. In this way, nonlinear signal processing techniques based on neural networks (NNs) are used in the proposed clutter reduction [...] Read more.
The presence of sea clutter in marine radar signals is sometimes not desired. So, efficient radar signal processing techniques are needed to reduce it. In this way, nonlinear signal processing techniques based on neural networks (NNs) are used in the proposed clutter reduction system. The developed experiments show promising results characterized by different subjective (visual analysis of the processed radar images) and objective (clutter reduction, target enhancement and signal-to-clutter ratio improvement) criteria. Moreover, a deep study of the NN structure is done, where the low computational cost and the high processing speed of the proposed NN structure are emphasized. Full article
(This article belongs to the Special Issue Neural Networks and Sensors)
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37 pages, 305 KB  
Review
Applications of SAR Interferometry in Earth and Environmental Science Research
by Xiaobing Zhou, Ni-Bin Chang and Shusun Li
Sensors 2009, 9(3), 1876-1912; https://doi.org/10.3390/s90301876 - 13 Mar 2009
Cited by 162 | Viewed by 26421
Abstract
This paper provides a review of the progress in regard to the InSAR remote sensing technique and its applications in earth and environmental sciences, especially in the past decade. Basic principles, factors, limits, InSAR sensors, available software packages for the generation of InSAR [...] Read more.
This paper provides a review of the progress in regard to the InSAR remote sensing technique and its applications in earth and environmental sciences, especially in the past decade. Basic principles, factors, limits, InSAR sensors, available software packages for the generation of InSAR interferograms were summarized to support future applications. Emphasis was placed on the applications of InSAR in seismology, volcanology, land subsidence/uplift, landslide, glaciology, hydrology, and forestry sciences. It ends with a discussion of future research directions. Full article
(This article belongs to the Special Issue Synthetic Aperture Radar (SAR))
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16 pages, 160 KB  
Article
Thiopental and Phenytoin as Novel Ionophores for Potentiometric Determination of Lead (II) Ions
by Nashwa M.H. Rizk, Samah S. Abbas, Salem M. Hamza, Salem M. Hamza and Yasser M. Abd EL-Karem
Sensors 2009, 9(3), 1860-1875; https://doi.org/10.3390/s90301860 - 13 Mar 2009
Cited by 11 | Viewed by 12315
Abstract
Two novel polymeric membrane sensors for the analysis of Pb(II) have been developed based ontwo therapeutic drugs, thiopental (TP) and phenytoin (PT) as two new ionophores and potassium tetrakis(p-chlorophenyl) borate (KTpClPB) as a lipophilic additive, in plasticized PVC membranes. [...] Read more.
Two novel polymeric membrane sensors for the analysis of Pb(II) have been developed based ontwo therapeutic drugs, thiopental (TP) and phenytoin (PT) as two new ionophores and potassium tetrakis(p-chlorophenyl) borate (KTpClPB) as a lipophilic additive, in plasticized PVC membranes. The sensors show a Nernstian response for Pb(II) ions over the wide concentration ranges of 1×10-2 - 7×10-6 M and 1×10-2 - 8×10-6 M for the sensors based on thiopental and phenytoin, respectively. The proposed sensors have a fast response time and can be used for more than nine weeks without any considerable divergence in potentials. The sensors exhibit comparatively good selectivity with respect to alkaline, alkaline earth and some transition and heavy metal ions. They were employed for direct determination of lead in solder alloys and in galena rocks with a good agreement with the obtained results by atomic absorption spectroscopy. Full article
(This article belongs to the Section Chemical Sensors)
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15 pages, 590 KB  
Article
An Evaluation of Relative Damage to the Powertrain System in Tracked Vehicles
by Sang-Ho Lee, Jeong-Hwan Lee Lee, Sang-Hwa Goo, Yong-Cheol Cho and Ho-Young Cho
Sensors 2009, 9(3), 1845-1859; https://doi.org/10.3390/s90301845 - 13 Mar 2009
Cited by 7 | Viewed by 13422
Abstract
The objective of this study was to improve the reliability of the endurance test for the powertrain system of military tracked vehicles. The measurement system that measures the driving duty applied to the powertrain system caused by mobility on roads consists of eight [...] Read more.
The objective of this study was to improve the reliability of the endurance test for the powertrain system of military tracked vehicles. The measurement system that measures the driving duty applied to the powertrain system caused by mobility on roads consists of eight analog channels and two pulse channels, including the propeller shaft output torques for the left and right sides. The data obtained from this measurement system can be used to introduce a new technology that produces the output torque of a torque converter and that can be applied to analyze the revolution counting for the endurance and road mobility in the front unit and represent the relative fatigue damages analysis technique and its results according to the driven roads through a cumulative fatigue method. Full article
(This article belongs to the Section Chemical Sensors)
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24 pages, 1184 KB  
Review
A Review on Direct Electrochemistry of Catalase for Electrochemical Sensors
by Periasamy Arun Prakash, Umasankar Yogeswaran and Shen-Ming Chen
Sensors 2009, 9(3), 1821-1844; https://doi.org/10.3390/s90301821 - 13 Mar 2009
Cited by 77 | Viewed by 20511
Abstract
Catalase (CAT) is a heme enzyme with a Fe(III/II) prosthetic group at its redox centre. CAT is present in almost all aerobic living organisms, where it catalyzes the disproportionation of H2O2 into oxygen and water without forming free radicals. [...] Read more.
Catalase (CAT) is a heme enzyme with a Fe(III/II) prosthetic group at its redox centre. CAT is present in almost all aerobic living organisms, where it catalyzes the disproportionation of H2O2 into oxygen and water without forming free radicals. In order to study this catalytic mechanism in detail, the direct electrochemistry of CAT has been investigated at various modified electrode surfaces with and without nanomaterials. The results show that CAT immobilized on nanomaterial modified electrodes shows excellent catalytic activity, high sensitivity and the lowest detection limit for H2O2 determination. In the presence of nanomaterials, the direct electron transfer between the heme group of the enzyme and the electrode surface improved significantly. Moreover, the immobilized CAT is highly biocompatible and remains extremely stable within the nanomaterial matrices. This review discusses about the versatile approaches carried out in CAT immobilization for direct electrochemistry and electrochemical sensor development aimed as efficient H2O2 determination. The benefits of immobilizing CAT in nanomaterial matrices have also been highlighted. Full article
(This article belongs to the Special Issue Nanotechnological Advances in Biosensors)
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14 pages, 293 KB  
Article
Leeches as Sensor-bioindicators of River Contamination by PCBs
by Stanislava Macova, Danka Harustiakova, Jitka Kolarova, Jana Machova, Vladimir Zlabek, Blanka Vykusova, Tomas Randak, Josef Velisek, Gorzyslaw Poleszczuk, Jana Hajslova, Jana Pulkrabova and Zdenka Svobodova
Sensors 2009, 9(3), 1807-1820; https://doi.org/10.3390/s90301807 - 13 Mar 2009
Cited by 11 | Viewed by 16032
Abstract
The aim of the study was to evaluate the use of leeches of the genus Erpobdella as a means of assessing polychlorinated biphenyl contamination of watercourses. The River Skalice, heavily contaminated with PCBs, was selected as a model. The source of contamination was [...] Read more.
The aim of the study was to evaluate the use of leeches of the genus Erpobdella as a means of assessing polychlorinated biphenyl contamination of watercourses. The River Skalice, heavily contaminated with PCBs, was selected as a model. The source of contamination was a road gravel processing factory in Rožmitál pod Třemšínem from which an estimated 1 metric ton of PCBs leaked in 1986. Levels of PCB were measured in leeches collected between 1992 to 2003 from 11 sites covering about 50 km of the river (the first sampling site upstream to the source of contamination and 10 sites downstream). The PCB indicator congeners IUPA no. 28, 52, 101, 118, 138, 153, and 180 were measured. Levels were highest at the four sampling sites nearest the source of pollution. The highest values of PCB congeners were found in 1992. PCB content decreased from 1992 to 2003 and with distance from the source. The study indicated that leeches of the genus Erpobdella are a suitable bioindicator of contamination in the surface layer of river sediments. Full article
(This article belongs to the Special Issue Tissue, Cell and Molecular Bioelectrochemistry - New Trends and Approaches)
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13 pages, 464 KB  
Article
Fabricating an Amperometric Cholesterol Biosensor by a Covalent Linkage between Poly(3-thiopheneacetic acid) and Cholesterol Oxidase
by Po-Chin Nien, Po-Yen Chen and Kuo-Chuan Ho
Sensors 2009, 9(3), 1794-1806; https://doi.org/10.3390/s90301794 - 13 Mar 2009
Cited by 34 | Viewed by 13044
Abstract
In this study, use of the covalent enzyme immobilization method was proposed to attach cholesterol oxidase (ChO) on a conducting polymer, poly(3-thiopheneacetic acid), [poly(3-TPAA)]. Three red-orange poly(3-TPAA) films, named electrodes A, B and C, were electropolymerized on a platinum electrode by applying a [...] Read more.
In this study, use of the covalent enzyme immobilization method was proposed to attach cholesterol oxidase (ChO) on a conducting polymer, poly(3-thiopheneacetic acid), [poly(3-TPAA)]. Three red-orange poly(3-TPAA) films, named electrodes A, B and C, were electropolymerized on a platinum electrode by applying a constant current of 1.5 mA, for 5, 20 and 100 s, respectively. Further, 1-ethyl-3-(3-dimethylamiopropyl)carbodiimide hydrochloride (EDC‧HCl) and N-hydroxysuccinimide (NHS) were used to activate the free carboxylic groups of the conducting polymer. Afterwards, the amino groups of the cholesterol oxidase were linked on the activated groups to form peptide bonds. The best sensitivity obtained for electrode B is 4.49 mA M-1 cm-2,with a linear concentration ranging from 0 to 8 mM, which is suitable for the analysis of cholesterol in humans. The response time (t95) is between 70 and 90 s and the limit of detection is 0.42 mM, based on the signal to noise ratio equal to 3. The interference of species such as ascorbic acid and uric acid increased to 5.2 and 10.3% of the original current response, respectively, based on the current response of cholesterol (100%). With respect to the long-term stability, the sensing response retains 88% of the original current after 13 days. Full article
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26 pages, 167 KB  
Review
Scale Issues in Remote Sensing: A Review on Analysis, Processing and Modeling
by Hua Wu and Zhao-Liang Li
Sensors 2009, 9(3), 1768-1793; https://doi.org/10.3390/s90301768 - 13 Mar 2009
Cited by 324 | Viewed by 23313
Abstract
With the development of quantitative remote sensing, scale issues have attracted more and more the attention of scientists. Research is now suffering from a severe scale discrepancy between data sources and the models used. Consequently, both data interpretation and model application become difficult [...] Read more.
With the development of quantitative remote sensing, scale issues have attracted more and more the attention of scientists. Research is now suffering from a severe scale discrepancy between data sources and the models used. Consequently, both data interpretation and model application become difficult due to these scale issues. Therefore, effectively scaling remotely sensed information at different scales has already become one of the most important research focuses of remote sensing. The aim of this paper is to demonstrate scale issues from the points of view of analysis, processing and modeling and to provide technical assistance when facing scale issues in remote sensing. The definition of scale and relevant terminologies are given in the first part of this paper. Then, the main causes of scale effects and the scaling effects on measurements, retrieval models and products are reviewed and discussed. Ways to describe the scale threshold and scale domain are briefly discussed. Finally, the general scaling methods, in particular up-scaling methods, are compared and summarized in detail. Full article
(This article belongs to the Section Remote Sensors)
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14 pages, 924 KB  
Article
Optimal Spectral Domain Selection for Maximizing Archaeological Signatures: Italy Case Studies
by Rosa Maria Cavalli, Simone Pascucci and Stefano Pignatti
Sensors 2009, 9(3), 1754-1767; https://doi.org/10.3390/s90301754 - 12 Mar 2009
Cited by 22 | Viewed by 14999
Abstract
Different landscape elements, including archaeological remains, can be automatically classified when their spectral characteristics are different, but major difficulties occur when extracting and classifying archaeological spectral features, as archaeological remains do not have unique shape or spectral characteristics. The spectral anomaly characteristics due [...] Read more.
Different landscape elements, including archaeological remains, can be automatically classified when their spectral characteristics are different, but major difficulties occur when extracting and classifying archaeological spectral features, as archaeological remains do not have unique shape or spectral characteristics. The spectral anomaly characteristics due to buried remains depend strongly on vegetation cover and/or soil types, which can make feature extraction more complicated. For crop areas, such as the test sites selected for this study, soil and moisture changes within near-surface archaeological deposits can influence surface vegetation patterns creating spectral anomalies of various kinds. In this context, this paper analyzes the usefulness of hyperspectral imagery, in the 0.4 to 12.8 mm spectral region, to identify the optimal spectral range for archaeological prospection as a function of the dominant land cover. MIVIS airborne hyperspectral imagery acquired in five different archaeological areas located in Italy has been used. Within these archaeological areas, 97 test sites with homogenous land cover and characterized by a statistically significant number of pixels related to the buried remains have been selected. The archaeological detection potential for all MIVIS bands has been assessed by applying a Separability Index on each spectral anomaly-background system of the test sites. A scatterplot analysis of the SI values vs. the dominant land cover fractional abundances, as retrieved by spectral mixture analysis, was performed to derive the optimal spectral ranges maximizing the archaeological detection. This work demonstrates that whenever we know the dominant land cover fractional abundances in archaeological sites, we can a priori select the optimal spectral range to improve the efficiency of archaeological observations performed by remote sensing data. Full article
(This article belongs to the Section Remote Sensors)
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17 pages, 670 KB  
Article
Quantitative Assessment of Desertification Using Landsat Data on a Regional Scale – A Case Study in the Ordos Plateau, China
by Duanyang Xu, Xiangwu Kang, Dongsheng Qiu, Dafang Zhuang and Jianjun Pan
Sensors 2009, 9(3), 1738-1753; https://doi.org/10.3390/s90301738 - 12 Mar 2009
Cited by 81 | Viewed by 17948
Abstract
Desertification is a serious threat to the ecological environment and social economy in our world and there is a pressing need to develop a reasonable and reproducible method to assess it at different scales. In this paper, the Ordos Plateau in China was [...] Read more.
Desertification is a serious threat to the ecological environment and social economy in our world and there is a pressing need to develop a reasonable and reproducible method to assess it at different scales. In this paper, the Ordos Plateau in China was selected as the research region and a quantitative method for desertification assessment was developed by using Landsat MSS and TM/ETM+ data on a regional scale. In this method, NDVI, MSDI and land surface albedo were selected as assessment indicators of desertification to represent land surface conditions from vegetation biomass, landscape pattern and micrometeorology. Based on considering the effects of vegetation type and time of images acquired on assessment indictors, assessing rule sets were built and a decision tree approach was used to assess desertification of Ordos Plateau in 1980, 1990 and 2000. The average overall accuracy of three periods was higher than 90%. The results showed that although some local places of Ordos Plateau experienced an expanding trend of desertification, the trend of desertification of Ordos Plateau was an overall decrease in from 1980 to 2000. By analyzing the causes of desertification processes, it was found that climate change could benefit for the reversion of desertification from 1980 to 1990 at a regional scale and human activities might explain the expansion of desertification in this period; however human conservation activities were the main driving factor that induced the reversion of desertification from 1990 to 2000. Full article
(This article belongs to the Section Remote Sensors)
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16 pages, 1105 KB  
Article
CMOS Image Sensor with a Built-in Lane Detector
by Pei-Yung Hsiao, Hsien-Chein Cheng, Shih-Shinh Huang and Li-Chen Fu
Sensors 2009, 9(3), 1722-1737; https://doi.org/10.3390/s90301722 - 12 Mar 2009
Cited by 4 | Viewed by 17262
Abstract
This work develops a new current-mode mixed signal Complementary Metal-Oxide-Semiconductor (CMOS) imager, which can capture images and simultaneously produce vehicle lane maps. The adopted lane detection algorithm, which was modified to be compatible with hardware requirements, can achieve a high recognition rate of [...] Read more.
This work develops a new current-mode mixed signal Complementary Metal-Oxide-Semiconductor (CMOS) imager, which can capture images and simultaneously produce vehicle lane maps. The adopted lane detection algorithm, which was modified to be compatible with hardware requirements, can achieve a high recognition rate of up to approximately 96% under various weather conditions. Instead of a Personal Computer (PC) based system or embedded platform system equipped with expensive high performance chip of Reduced Instruction Set Computer (RISC) or Digital Signal Processor (DSP), the proposed imager, without extra Analog to Digital Converter (ADC) circuits to transform signals, is a compact, lower cost key-component chip. It is also an innovative component device that can be integrated into intelligent automotive lane departure systems. The chip size is 2,191.4 x 2,389.8 mm, and the package uses 40 pin Dual-In-Package (DIP). The pixel cell size is 18.45 x 21.8 mm and the core size of photodiode is 12.45 x 9.6 mm; the resulting fill factor is 29.7%. Full article
(This article belongs to the Special Issue Image Sensors 2009)
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8 pages, 381 KB  
Communication
Humidity Sensitivity of Multi-Walled Carbon Nanotube Networks Deposited by Dielectrophoresis
by Litao Liu, Xiongying Ye, Kang Wu, Rui Han, Zhaoying Zhou and Tianhong Cui
Sensors 2009, 9(3), 1714-1721; https://doi.org/10.3390/s90301714 - 11 Mar 2009
Cited by 128 | Viewed by 16722
Abstract
This paper presents an investigation on the humidity sensitivity of deposited multi-walled carbon nanotube (MWCNT) networks using ac dielectrophoresis (DEP) between interdigitated electrodes (IDEs). MWCNTs dispersed in ethanol were trapped and enriched between IDEs on a Si/SiO2 substrate under a positive DEP [...] Read more.
This paper presents an investigation on the humidity sensitivity of deposited multi-walled carbon nanotube (MWCNT) networks using ac dielectrophoresis (DEP) between interdigitated electrodes (IDEs). MWCNTs dispersed in ethanol were trapped and enriched between IDEs on a Si/SiO2 substrate under a positive DEP force. After the DEP process, the ethanol was evaporated and the MWCNT network on a substrate with IDEs was put into a furnace for repeated thermal annealing. It was found that the resistance stability of the network was effectively improved through thermal annealing. The humidity sensitivity was obtained by measuring the resistance of the MWCNT network with different relative humidity at room temperature. The experimental results show the resistance increases linearly with increasing the relative humidity from 25% to 95% RH with a sensitivity of 0.5%/%RH. The MWCNT networks have a reversible humidity sensing capacity with response time and recovery time of about 3 s and 25 s, respectively. The resistance is dependent on temperature with a negative coefficient of about -0.33%/K in a temperature range from 293 K to 393 K. Full article
(This article belongs to the Special Issue Selected Papers from the 1st International Conference of the Chinese Society of Micro/Nano Technology)
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22 pages, 847 KB  
Article
Noise Reduction for CFA Image Sensors Exploiting HVS Behaviour
by Angelo Bosco, Sebastiano Battiato, Arcangelo Bruna and Rosetta Rizzo
Sensors 2009, 9(3), 1692-1713; https://doi.org/10.3390/s90301692 - 10 Mar 2009
Cited by 20 | Viewed by 16313
Abstract
This paper presents a spatial noise reduction technique designed to work on CFA (Color Filtering Array) data acquired by CCD/CMOS image sensors. The overall processing preserves image details using some heuristics related to the HVS (Human Visual System); estimates of local texture degree [...] Read more.
This paper presents a spatial noise reduction technique designed to work on CFA (Color Filtering Array) data acquired by CCD/CMOS image sensors. The overall processing preserves image details using some heuristics related to the HVS (Human Visual System); estimates of local texture degree and noise levels are computed to regulate the filter smoothing capability. Experimental results confirm the effectiveness of the proposed technique. The method is also suitable for implementation in low power mobile devices with imaging capabilities such as camera phones and PDAs. Full article
(This article belongs to the Special Issue Integrated High-performance Imagers)
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14 pages, 175 KB  
Article
Least Square Regression Method for Estimating Gas Concentration in an Electronic Nose System
by Walaa Khalaf, Calogero Pace and Manlio Gaudioso
Sensors 2009, 9(3), 1678-1691; https://doi.org/10.3390/s90301678 - 10 Mar 2009
Cited by 41 | Viewed by 15661
Abstract
We describe an Electronic Nose (ENose) system which is able to identify the type of analyte and to estimate its concentration. The system consists of seven sensors, five of them being gas sensors (supplied with different heater voltage values), the remainder being a [...] Read more.
We describe an Electronic Nose (ENose) system which is able to identify the type of analyte and to estimate its concentration. The system consists of seven sensors, five of them being gas sensors (supplied with different heater voltage values), the remainder being a temperature and a humidity sensor, respectively. To identify a new analyte sample and then to estimate its concentration, we use both some machine learning techniques and the least square regression principle. In fact, we apply two different training models; the first one is based on the Support Vector Machine (SVM) approach and is aimed at teaching the system how to discriminate among different gases, while the second one uses the least squares regression approach to predict the concentration of each type of analyte. Full article
(This article belongs to the Section Chemical Sensors)
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