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

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289 KiB  
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 35 | Viewed by 14059
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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<p>Biotinylation and conjugation of the lactoferrin.</p> Full article ">
<p>Amperometric immunosensor for lactoferrin determination using hydrogen peroxide electrode as transducer.</p> Full article ">
<p>Determination of lactoferrin by immunosensor, Test geometry: competition between lactoferrin biotin-avidin-peroxidase conjugated and lactoferrin, both free in solution for Anti-lactoferrin immobilized in membrane.</p> Full article ">
<p>(a) Behaviour of the lactoferrin immunosensor response as a function of increasing lactoferrin concentration, using Immobilon membrane and an amperometric electrode for H<sub>2</sub>O<sub>2</sub> as transducer; (b) corresponding calibration curve and confidence interval for the lactoferrin determination, (Sc = sample signal/nA; Sb = blank signal/nA).</p> Full article ">
<p>Immunosensor for IgG determination.</p> Full article ">
<p>Determination of antigen (IgG) by new immunosensor using tyrosinase enzyme electrode as a transducer. Test geometry: competition for anti-IgG alkaline phosphatase conjugated between IgG immobilized on membrane and IgG free in solution.</p> Full article ">
<p>(a) Behaviour of the IgG immunosensor response as a function of increasing IgG concentration using Immobilon membrane and tyrosinase biosensor as a transducer; (b) corresponding calibration curve and confidence interval for IgG determination.</p> Full article ">
<p>Trends in: (a) lactoferrin concentration; (b) IgG concentration; (c) Antioxidant capacity; in buffalo milk samples as a function of increasing days of lactation.</p> Full article ">
1172 KiB  
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 39 | Viewed by 13269
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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<p>Concept of the proposed diagnosis support system for finger tapping movements.</p> Full article ">
<p>Examples of the measured signals. [<a href="#b12-sensors-09-02187" class="html-bibr">12</a>]</p> Full article ">
<p>An example of the spectral variability of finger taps, note that UPDRS-FT 2 stands for the Unified Parkinson’s Disease Rating Scale part III finger tapping score 2. [<a href="#b13-sensors-09-02187" class="html-bibr">13</a>]</p> Full article ">
<p>Structure of the LLGMN. [<a href="#b10-sensors-09-02187" class="html-bibr">10</a>]</p> Full article ">
<p>Strategy for combining LLGMNs</p> Full article ">
<p>The prototype system developed and the experimental setup.</p> Full article ">
<p>Measured results of finger tapping movements. [<a href="#b12-sensors-09-02187" class="html-bibr">12</a>]</p> Full article ">
<p>Examples of radar chart representation of the results from the evaluated indices. [<a href="#b12-sensors-09-02187" class="html-bibr">12</a>]</p> Full article ">
<p>Discrimination rates of finger tapping movements.</p> Full article ">
180 KiB  
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 25 | Viewed by 13027
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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<p>Schematic representation of the immobilized cell biosensor. The reference electrode is manually inserted in a cell-free gel bead, while the measuring electrode is inserted in the immobilized cell-loaded gel bead. Neither electrode is in direct contact with the sample solution (i.e. only beads are immersed into sample). The approximate diameter of the beads is two mm. Both measurement and reference electrodes are connected to the PMD 1608-FS converter.</p> Full article ">
<p>Biosensor response against HBsAg. The sensor is based on Vero cells membrane-engineered with the anti-HBs antibody. Sensor response is expressed as an associated change in the membrane potential of immobilized cells. Error bars represent standard errors of the average value of all replications with each sample (<span class="html-italic">n</span> = 15 replications for each sample).</p> Full article ">
<p>Biosensor response against HBeAg. The sensor is based on Vero cells membrane-engineered with the anti-HBe antibody. Sensor response is expressed as an associated change in the membrane potential of immobilized cells. Error bars represent standard errors of the average value of all replications with each sample (<span class="html-italic">n</span> = 15 replications for each sample).</p> Full article ">
<p>Biosensor response against the anti-HBs antibody. The sensor is based on Vero cells membrane-engineered with HBsAg. Sensor response is expressed as an associated change in the membrane potential of immobilized cells. Error bars represent standard errors of the average value of all replications with each sample (<span class="html-italic">n</span> = 15 replications for each sample).</p> Full article ">
<p>Changes (expressed as differences in fluorescence intensity) of the cytoplasmic calcium ion concentration in Vero cells, membrane-engineered with anti-HBs (A, B), anti-HBe (C, D) and HBsAg (E, F), before (A, C, E) and after (B, D, F) treatment with the HBsAg, HBeAg and anti-HBs respectively.</p> Full article ">
1206 KiB  
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 11432
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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<p>The structure of a single GLM.</p> Full article ">
<p>The operating principle of the GLM.</p> Full article ">
<p>The diffraction intensity distribution of the GLM. <b>(a)</b> The phase difference is 2n'π. <b>(b)</b> The phase difference is (2n'+1)π.</p> Full article ">
<p>A SEM photograph of passive matrix addressing for the 16×16 GLM array.</p> Full article ">
<p>The fabrication process of GLM.</p> Full article ">
<p>The photograph of the fabricated GLM array. <b>(a)</b> The SEM photograph of parts of a GLM array. <b>(b)</b> The VEECO photograph of parts of the fabricated GLM array.</p> Full article ">
<p>The structure and the parameters of the GLM. <b>(</b>a) The top image; (b) The cross-section image.</p> Full article ">
<p>The simulation of the displacement and the driving voltage.</p> Full article ">
<p>The matrix capacitance model of a m×n GLM array. (a) The initial model. (b) The simplified model.</p> Full article ">
286 KiB  
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 207 | Viewed by 18993
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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Graphical abstract

Graphical abstract
Full article ">
<p>Pre-processing result. (A) Original I band. (B) I band after pre-processing. (C) Standard deviation of (A).</p> Full article ">
<p>Blood vessel and optic disc detection. (A) Blood vessel detected from decorrelation stretch image. (B) Optic disc area eliminated from the contrast enhanced image.</p> Full article ">
<p>Input features for FCM clustering of image1. (A) Intensity image after preprocessing. (B) Standard deviation of intensity image. (C) Hue image. (D) Image of edge pixels.</p> Full article ">
<p>FCM clustering results with n=8. (A) Cluster 1. (B) Cluster 2. (C) Cluster 3. (D) Cluster 4. (E) Cluster 5. (F) Cluster 6. (G) Cluster 7. (H) Cluster 8.</p> Full article ">
<p>FCM clustering results with n=8. (A) Cluster 1. (B) Cluster 2. (C) Cluster 3. (D) Cluster 4. (E) Cluster 5. (F) Cluster 6. (G) Cluster 7. (H) Cluster 8.</p> Full article ">
<p>Exudates detection (A) Candidate areas after using FCM clustering. (B) Marker image. (C) Mask image. (D) Reconstructed image. (E) Difference image. (F) Result superimposed on the original image.</p> Full article ">
<p>Comparison of exudates detection. (A) Coarse segmentation using FCM clustering. (B) Fine segmentation using morphological reconstruction (C) Ground truth image.</p> Full article ">
<p>Exudates detection on low contrast images (A), (C) and (E) are original images, (B), (D) and (F) are detected exudates superimposed on original images of (A), (C) and (E) respectively.</p> Full article ">
166 KiB  
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 15783
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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<p>The standard calibration for the quantification of resorufin by HPLC (the linear regression equation for the calibration curve is y = 21.7x + 5.1; coefficient of determination is 0.9998). The fluorescence detection was performed at an excitation wavelength of 560 nm and emission wavelength of 586 nm.</p> Full article ">
<p>Saturation curve for 7-ethoxyresorufin <span class="html-italic">O</span>-deethylation by hepatic microsomes from entire (a) and castrated (b) male pigs. Insets: Eadie-Hofstee transformations of the same data. V – velocity of resorufin formation; S - substrate.</p> Full article ">
<p>Saturation curve for 7-methoxyresorufin <span class="html-italic">O</span>-demethylation by hepatic microsomes from entire (a) and castrated (b) male pigs. Insets: Eadie-Hofstee transformations of the same data. V – velocity of resorufin formation; S - substrate.</p> Full article ">
<p>Inhibition of 7-ethoxyresorufin <span class="html-italic">O</span>-deethylation (EROD) in hepatic microsomes from castrated and entire male pigs by ANF (a), ellipticine (b) and furafylline (c). Assays were performed as described in the Experimental section. Values are expressed as percentages of activities in control incubations and are the mean of duplicates (differences between the duplicates were below 10%).</p> Full article ">
<p>Inhibition of 7-methoxyresorufin <span class="html-italic">O</span>-demethylation (MROD) in hepatic microsomes from entire and castrated male pigs by ANF (a), ellipticine (b) and furafylline (c). Assays were performed as described in the Experimental section. Values are expressed as percentages of activities in control incubations and are the mean of duplicates (differences between the duplicates were below 10%).</p> Full article ">
248 KiB  
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 37 | Viewed by 15674
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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<p>Representative neuroblastoma response in the MMP to 100 nM Ricin. Glucose and oxygen extracellular concentrations are inversely proportional to cellular uptake rates.</p> Full article ">
<p>Representative BoNT/A kinetic metabolic profiles and partial dose response curves in [substrate] vs. log [BoNT/A] with sequential increasing concentration of BoNT/A.</p> Full article ">
<p>Representative effect of 15 mM alamethicin on RAW macrophage cells.</p> Full article ">
<p>Representative RAW macrophage response to 1 and 2 μM anthrax PA.</p> Full article ">
<p>Representative CHO cell response to 1 μM cholera toxin followed by stimulation with 10 μM muscarine.</p> Full article ">
<p>Binary four-by-four Karnaugh map of toxin responses. A ‘0’ indicates a decrease and a ‘1’ indicates an increase in the rate of consumption/production of analyte in response to the indicated analyte. BT = botulinum neurotoxin A, CT = cholera toxin, DNP = 2,4-dinitrophenol, MU = muscarine, APA = anthrax protective antigen, Ala = alamethicin, RT = ricin toxin, NaF = sodium fluoride. DNP, NaF from ref. [<a href="#b17-sensors-09-02117" class="html-bibr">17</a>].</p> Full article ">
<p>Combined representative metabolic profiles of all toxins for comparison in <a href="#f6-sensors-09-02117" class="html-fig">Figure 6</a>.</p> Full article ">
367 KiB  
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 24 | Viewed by 16444
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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<p>Factors affecting availability and reliability evaluated in this paper.</p> Full article ">
<p>Quality of service (QoS) parameters in WSNs. The shown network QoS profile emphasizes reliability, availability, data accuracy, and energy-efficiency.</p> Full article ">
<p>Sleep schedules in a low duty cycle network. A node forwards data during the active period of a neighbor node.</p> Full article ">
<p>Availability metric expressing the probability that an update is received from a node within certain time interval. Packet drops and network errors decrease the availability.</p> Full article ">
<p>Superframe structure in IEEE 802.15.4 LR-WPAN with beacon enabled mode.</p> Full article ">
<p>Superframe structure in TUTWSN MAC. CAP and CFP are divided into fixed time slots comprising two subslots, one for data frame and another for acknowledgment.</p> Full article ">
<p>Simulation topology. A link is drawn between nodes within communication range.</p> Full article ">
<p>Beacon losses due to packet errors. TUTWSN is presented with synchronization loss after 3 and 4 consecutive beacon misses. ZigBee uses the default 4.</p> Full article ">
<p>Synchronization losses due to several consecutive beacon misses.</p> Full article ">
190 KiB  
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 8 | Viewed by 13254
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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<p>The fabrication process flow for a REFET based on a Si<sub>3</sub>N<sub>4</sub>-ISFET.</p> Full article ">
<p>pH sensitivity of (a) a Si<sub>3</sub>N<sub>4</sub> ISFET without a PVC membrane, and REFETs with membranes containing different plasticizers at 70 wt.% composition: (b) DNP, (c) DOS, and (d) <span class="html-italic">o</span>-NPOE.</p> Full article ">
<p>pH response of the REFET with the optimized composition of the DNP solution for the PVC membrane.</p> Full article ">
<p>The time-dependent distribution of the sensitivity and linearity of REFETs with PVC membranes fabricated with a 60 wt. % DNP cocktail.</p> Full article ">
<p>The I<sub>DS</sub>-V<sub>DS</sub> curves of ISFETs and REFETs with the gate voltage varied from 0 V to 3 V.</p> Full article ">
<p>The I<sub>DS</sub>-V<sub>GS</sub> curves and transconductance (g<sub>m</sub>) of ISFETs and REFETs measured at V<sub>DS</sub> = 0.5V.</p> Full article ">
<p>The I<sub>DS</sub>-V<sub>GS</sub> and sensitivity of REFETs with (a) V<sub>DS</sub> = 0.5 V and (b) V<sub>DS</sub> = 2.5 V. Insets show calibration curves corresponding to I<sub>DS</sub>-V<sub>GS</sub> curves.</p> Full article ">
647 KiB  
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 31 | Viewed by 13196
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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<p>Schematic structure of the tunable resonator.</p> Full article ">
<p>Maximum amplitude of the tunable resonator at different damping ratios.</p> Full article ">
<p>Tuning-comb of the tunable resonator.</p> Full article ">
<p>Stiffness ratio of the tunable resonator with different shape factors.</p> Full article ">
<p>Frequency ratio vs. stiffness ratio.</p> Full article ">
<p>Frequency ratio of the tunable resonator with different shape factors.</p> Full article ">
<p>Stress distribution of the resonator.</p> Full article ">
<p>Layout of the tunable resonator.</p> Full article ">
<p>Optical image of the tunable resonator after completion of the CMOS process.</p> Full article ">
825 KiB  
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 52 | Viewed by 17067
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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<p>Cbers1 image of Guojiaba Town in Three Gorges.</p> Full article ">
<p>Cbers2 image of Guojiaba Town in Three Gorges.</p> Full article ">
<p>Cbers3 image of Guojiaba Town in Three Gorges.</p> Full article ">
<p>Cbers4 image of Guojiaba Town in Three Gorges.</p> Full article ">
<p>1: 0.05 million geological map of Guojiaba.</p> Full article ">
<p>Cbers image composed of 432 spectra in Three Gorges.</p> Full article ">
<p>Cbers image composed of 432 spectra in Guojiaba Town.</p> Full article ">
<p>Cbers image piled up with landslide disaster distribution graph.</p> Full article ">
<p>Cbers3/Cbers2 image.</p> Full article ">
1281 KiB  
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 13485
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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<p>Outline tectonic map of the easternmost Mediterranean area, showing the main neotectonic lineaments and the main structural units in the text. Seismicity of the Western Anatolia in the last century with <span class="html-italic">M</span>s &gt; 4.</p> Full article ">
<p>The focal mechanisms of the earthquakes in the Southwest Anatolia (M &gt; 5.5) [<a href="#b19-sensors-09-02017" class="html-bibr">19</a>].</p> Full article ">
<p>IGS stations used both processing and data transformation.</p> Full article ">
<p>Horizontal velocity field in the Eurasia-fixed frame (ellipses are at 95 % confidence level).</p> Full article ">
<p>Residual values between measured horizontal values (red arrow) and Euler pole values of McClusky (black arrow).</p> Full article ">
<p>Principal Strain rates. Blue and red arrows show maximum extension and compression, respectively in 10 <sup>−7</sup> strain/year.</p> Full article ">
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884 KiB  
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 52 | Viewed by 14546
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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Graphical abstract

Graphical abstract
Full article ">
<p>Determination of dominant wavelength and purity of color by CIE system.</p> Full article ">
<p>Changes of average reflectance (Y, %) on the top surface of samples of dietary chocolates during storage of 360 days.</p> Full article ">
<p>Changes of average reflectance (Y, %) on the bottom surface of samples of dietary chocolates during storage of 360 days.</p> Full article ">
<p>Changes of psychometric light (L*) on the top surface of samples of dietary chocolates during storage of 360 days.</p> Full article ">
<p>Changes of psychometric light (L*) on the bottom surface of samples of dietary chocolates during storage of 360 days.</p> Full article ">
<p>Changes of whiteness index (WI) on the top surface of samples of dietary chocolates during storage of 360 days.</p> Full article ">
<p>Changes of whiteness index (WI) on the bottom surface of samples of dietary chocolates during storage of 360 days.</p> Full article ">
<p>Changes of color difference (ΔE) on the top surface of samples of dietary chocolates during storage of 360 days.</p> Full article ">
<p>Changes of color difference (ΔE) on the bottom surface of samples of dietary chocolates during storage of 360 days.</p> Full article ">
705 KiB  
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 47 | Viewed by 15193
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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<p>Different spatial resolution DEMs of the Yangjiahe river watershed, (a) represents the 30m DEM constructed with 1:50,000 topographic map; (b) represents the 30m DEM re-sampled with 90 m SRTM DEM.</p> Full article ">
<p>Color composite of RGB-543 Landsat-7 ETM+ image of the study watershed before topographic correction.</p> Full article ">
<p>Comparison of color composite of RGB-543 Landsat-7 ETM+ image derived from two topographic correction methods being applied: (a) and (b) shows the image after SCS correction based on SRTM DEM and the DEM constructed from 1:50,000 scale topographic map respectively; (c) and (d) presents the image after Minnaert correction based on SRTM DEM and the DEM constructed from 1:50,000 scale topographic map respectively.</p> Full article ">
<p>S scatter plots and the linear regression fitting lines of reflectance ρ versus cosi for ETM+ band 1 before and after correction: (a) based on 90 m SRTM DEM; (b) based on DEM constructed from 1:50,000 scale topographic map; (1) before topographic correction; (2) SCS correction; (3) Minnaert correction.</p> Full article ">
<p>Image map of LULC Classification after topographic correction for the Yangjiahe river watershed: (a) and (b) illustrates the classification result after SCS correction based on SRTM DEM and the DEM constructed from 1:50,000 scale topographic map respectively; (c) and (d) exhibits the classification result after Minnaert correction based on SRTM DEM and the DEM constructed from 1:50,000 scale topographic map respectively.</p> Full article ">
<p>Image map of LULC Classification after topographic correction for the Yangjiahe river watershed: (a) and (b) illustrates the classification result after SCS correction based on SRTM DEM and the DEM constructed from 1:50,000 scale topographic map respectively; (c) and (d) exhibits the classification result after Minnaert correction based on SRTM DEM and the DEM constructed from 1:50,000 scale topographic map respectively.</p> Full article ">
428 KiB  
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 69 | Viewed by 14917
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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<p>3D Digitizing process and it’s applications in the automotive industry.</p> Full article ">
<p>Breuckmann Opto-TOP digitizing system: (a) image of the instrument; and (b) Setup fringe projection system</p> Full article ">
<p>(a) Calibration plate and (b) Angle master</p> Full article ">
<p>Preparation of the scanned part.</p> Full article ">
<p>(a) Scanning male and female dies, (b) merging images.</p> Full article ">
<p>Surface modeling procedure from scanned data: a) Point cloud, b) polygon meshes, c) mesh treatment, d) surface modeling.</p> Full article ">
<p>(a) STL file after combining scan shots, (b) Determining of the hole contours.</p> Full article ">
<p>(a) Using silhouette function for contours, (b) 3D cad model of the die.</p> Full article ">
<p>(a) STL data of scanned model, (b) 3D CAD surface model of the scanned sheet metal part.</p> Full article ">
353 KiB  
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 36 | Viewed by 16598
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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<p>Model structure for the dendron substituted tetraphenyl Zn-porphyrin (TPPZn) molecule used in the calculations.</p> Full article ">
<p>Flourescence excitation spectra of the G0 (solid), G2 (dash) and G4 (dotted) variants of dendrimer capped TPP. (a) Acetonide-G<sub>x</sub>-prop-TPPH<sub>2</sub> for emission at 650 nm. (b) Acetonide-G<sub>x</sub>-prop-TPPZn for emission at 660 nm.</p> Full article ">
<p>(a) Infrared absorption spectra of the HO-TPPH<sub>2</sub> (solid) and HO-TPPZn (dashed) molecules. (b) Infrared absorption spectra of the HO-prop-TPPH<sub>2</sub> (solid) and HO-prop-TPPZn (dashed) molecules. N.b., the spectra of panel a) was added a constant (0.25) in order to make the plot.</p> Full article ">
<p>(a) Infrared absorption spectra of Acetonide-G2-prop-TPPH<sub>2</sub> (solid) and Acetonide-G2-prop-TPPZn (dashed) molecules. (b) Infrared absorption spectra of Acetonide-G5-prop-TPPH<sub>2</sub> (solid) and Acetonide-G5-prop-TPPZn (dashed) molecules. N.b., the spectra of panel a) was added a constant (0.3) in order to make the plot.</p> Full article ">
<p>Emission spectra (logarithmic scale) of Acetonide-G0-prop-TPPH<sub>2</sub> (solid/black), Acetonide-G3-prop-TPPH (dashed/red), and Acetonide-G5-prop-TPPH (dotted/green). Concentration 0.010 mM (THF); excitation wavelenth 403 nm. Slits 5 and 10 nm for excitation and emission, respectively.</p> Full article ">
<p>Emission spectra (logarithmic scale) of Acetonide-G0-prop-TPPZn (solid/black), Acetonide-G4-prop-TPPZn (dashed/red), and Acetonide-G5-prop-TPPZn (dotted/green). Concentration 0.010 mM (THF); excitation wavelenth 403 nm. Slits 5 and 10 nm for excitation and emission, respectively.</p> Full article ">
<p>Emission decay of Acetonide-G2-prop-TPPZn (0.050 mM). Red dots: Excited at 403 nm with emission monitored at 650 nm. Blue triangles: Excited at 403 nm with emission monitored at 600 nm. Black squares is system response used for de-convolution fit; slit 32 nm.</p> Full article ">
<p>Emission decay of Acetonide-G5-prop-TPPZn (0.050 mM). Red dots: Excited at 403 nm with emission monitored at 650 nm. Blue triangles: Excited at 403 nm with emission monitored at 600 nm. Black squares is system response used for de-convolution fit; slit 32 nm.</p> Full article ">
2130 KiB  
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 16259
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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<p>FINO 1 Emplacement in the North Sea and Measuring and Monitoring Marine System Location</p> Full article ">
<p>Measuring and Monitoring Marine System</p> Full article ">
<p>NN-based clutter reduction system</p> Full article ">
<p>Training, Validation and Test Sets Composition from the Radar Image Database</p> Full article ">
<p>Example of Scan Maps containing Target and Clutter at the Input and Output of the NN-based Clutter Reduction System</p> Full article ">
<p>Example of Scan Maps containing only Clutter at the Input and Output of the NN-based Clutter Reduction System</p> Full article ">
305 KiB  
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 149 | Viewed by 24803
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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<p>A geometric model for a SAR system. <span class="html-italic">Slant range</span> is the length between the antenna and ground pixel and <span class="html-italic">ground range</span> is the distance between the ground track and the ground pixel.</p> Full article ">
<p>The relationship among amplitude, phase, and wavelength of a radar signal. The intensity of the radar signal is proportional to the squared amplitude.</p> Full article ">
160 KiB  
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 10 | Viewed by 11944
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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<p>Chemical structure of lead (II) ionophores.</p> Full article ">
<p>Effect of the pH on the potential responses of; (A) (PT) sensor with additive and (B) (TP) sensor with additive at (♦) 1.0×10<sup>−2</sup> M and (▴) 1.0×10<sup>−3</sup> M lead concentration.</p> Full article ">
<p>Potentiometric responses of lead membrane sensors based on (TP) with additive as ionophore toward several metal ions.</p> Full article ">
<p>Potentiometric responses of lead membrane sensors based on (PT) with additive as ionophore toward several metal ions.</p> Full article ">
590 KiB  
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 6 | Viewed by 12967
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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<p>Torque sensor for the propeller shaft.</p> Full article ">
<p>Speed sensor for the final drive.</p> Full article ">
<p>Tacho-generator for the engine RPM measurement.</p> Full article ">
<p>3D profile for the cross-country course.</p> Full article ">
<p>Propeller shaft torque of the cross-country course.</p> Full article ">
<p>Engine RPM and transmission Level of the cross-country course.</p> Full article ">
<p>Vehicle speed and final drive speed of the cross-country course.</p> Full article ">
<p>Configuration of the torque transmission for the tracked vehicle.</p> Full article ">
<p>Output torque of the torque converter for the gravel course.</p> Full article ">
1184 KiB  
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 74 | Viewed by 19850
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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<p>Schematic representation of the process involved in the encapsulation of CAT into polymer multilayers using biocrystals as templates. (Steps 1, 2) stepwise deposition of poly electrolyte layers; (Step 3) Exposure of the enzyme to solutions of pH &gt; 6 or acidic solution (pH &lt; 4), which results in the morphology change of the polymer capsule accompanied by the solubilisation of the enzyme; (Step 4) Exposure of the enzyme to solutions of pH &gt; 11 leads to the release of the enzyme by rupturing of the polymer capsule; (Step 5) Exposure of the encapsulated enzyme to an oxidizing solution results in the decomposition of the enzyme and thus enzyme expelled from the interior of the capsule through the polymer walls, leaving behind the hollow polymer capsules (reproduced with permission from Caruso <span class="html-italic">et al. Langmuir</span> <b>2000</b>, <span class="html-italic">16</span>, 1485–1488).</p> Full article ">
<p>CD spectra of CAT (— —), DDAB (– – –), CAT-DDAB (—) films. CAT was prepared in pH 6.1, 10 mM phosphate buffer solution (PBS) with 50 mmol: l KCl. Temperature: 25°C (reproduced with permission from Chen <span class="html-italic">et al. Biosens. Bioelectron</span>. <b>2001</b>, <span class="html-italic">16</span>, 115–120)</p> Full article ">
<p>UV–vis absorption spectra of (a) dry CAT film, (b) dry CAT-PAM film, and CAT-PAM films in different pH buffer solutions: (c) pH 7.0; (d) pH 5.0; (e) pH 9.0 and (f) pH 3.0 (reproduced with permission from Lu <span class="html-italic">et al. Biophys. Chem</span>. <b>2003</b>, <span class="html-italic">104</span>, 623–632).</p> Full article ">
<p>Amperometric i-t responses observed at different heme-proteins-SF/GCEs at − 0.2V in 10 ml of PBS pH 7.0 for 10μl injection of 22 mM H<sub>2</sub>O<sub>2</sub> for every 80 s: (a) SF films; (b) Mb–SF films; (c) Hb–SF films; (d) CAT–SF films; and (e) HRP–SF films (reproduced with permission from Wu <span class="html-italic">et al. Anal. Chim. Acta</span> <b>2006</b>, <span class="html-italic">558</span>, 179–186).</p> Full article ">
<p>AFM images of: (a) Cysteine/Silica sol–gel and; (b) CAT/cysteine/Si sol–gel modified Au electrodes (reproduced with permission from Di <span class="html-italic">et al. Biosens. Bioelectron</span>. <b>2006</b>, <span class="html-italic">22</span>, 247–252).</p> Full article ">
<p>(a) CVs of CAT (adsorbed from a 50 μM CAT solution) at a bare Au electrode (b) SWCNTs-Au modified electrode with CAT and (c) SWCNTs-Au modified electrode without CAT. The electrolyte solution used was 0.05 M PBS pH 5.9 and the scan rate employed was 0.1 V s<sup>−1</sup> (reproduced with permission from Wang <span class="html-italic">et al. Electroanalysis</span> <b>2004</b>, <span class="html-italic">16</span>, 627–632).</p> Full article ">
<p>CVs of SWNTs-CS-CAT-GCE in PBS pH 7 at a scan rate of 0.1 V s<sup>−1</sup> in the presence of (a) 0, (b) 1, and (c) 4 mM H<sub>2</sub>O<sub>2</sub> (reproduced with permission from Jiang <span class="html-italic">et al. J. Electroanal. Chem</span>. <b>2008</b>, <span class="html-italic">623</span>, 181–186).</p> Full article ">
<p>CVs of (a) NF-GNP-PGE, (b) NF-CAT-PGE, (c) NF-CAT-GNP-PGE (d) NF-CAT-GNP-MWCNTs-PGE electrode in 0.1 M pH 6.98 PBS at scan rate of 100 mV s<sup>−1</sup> (reproduced with permission from Zhou <span class="html-italic">et al. Anal. Lett</span>. <b>2008</b>, <span class="html-italic">41</span>, 1832–1849).</p> Full article ">
<p>The possible interaction between MWCNTs, NF, DDAB and CAT in MWCNTs-NF-(DDAB/CAT) film modified electrodes. (Reproduced with permission from Prakash <span class="html-italic">et al. Talanta</span>, doi:10.1016/j.talanta.2009.02.033, article in press).</p> Full article ">
293 KiB  
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 10 | Viewed by 15425
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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<p>Polychlorinated biphenyls (PCBs).</p> Full article ">
<p>The main used bioindicator species - <span class="html-italic">Erpobdella octoculata.</span></p> Full article ">
<p>Collection of leeches in the Skalice River.</p> Full article ">
<p>Locations of sites (Czech Republic).</p> Full article ">
<p>Σ PCB content in leeches from the River Skalice during 1992–2003. See <a href="#t1-sensors-09-01807" class="html-table">table 1</a> for site codes. (Σ PCB content at site 5 in 1992 was 2763.0 μg.kg<sup>−1</sup> in 1993 it was 767.0 μg.kg<sup>−1</sup>).</p> Full article ">
464 KiB  
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 32 | Viewed by 12658
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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<p>Schematic illustration of the sensing mechanism proposed for electrocatalytic oxidation of cholesterol on the modified electrode, where ferrocene acts as a mediator.</p> Full article ">
<p>The chronopotentiometry of the poly(3-TPAA) film electroploymerized at a constant current of 1.5 mA for 100 s in an organic electrolyte.</p> Full article ">
<p>The FTIR spectra of Pt/poly(3-TPAA) film (bold line) and Pt/poly(3-TPAA)-ChO film (thin line) at room temperature.</p> Full article ">
<p>The SEM pictures of <b>(a)</b> Pt/poly(3-TPAA) and <b>(b)</b> Pt/poly(3-TPAA)-ChO.</p> Full article ">
<p>The electrochemical impedance spectroscopy data for the Pt, Pt/poly(3-TPAA) and Pt/poly(3-TPAA)-ChO electrodes in 0.1 M PBS with 1.0 mM Fe(CN)<sub>6</sub><sup>3−</sup>.</p> Full article ">
<p>The LSV of electrode C scanned from 0.30 to 0.80 V (<span class="html-italic">vs</span>. Ag/AgCl/sat’d KCl) in background electrolyte (a) and 8 mM cholesterol solution (b), at a scan rate of 0.1 mV/s.</p> Full article ">
<p>(a) The current responses of the cholesterol at different concentrations by applying the sensing potential at 0.70 V (<span class="html-italic">vs.</span> Ag/AgCl/sat’d KCl) on electrode C and (b) the calibration curves of the three modified cholesterol biosensors at 0.70 V with regressions.</p> Full article ">
<p>The long-term stability of the cholesterol biosensor at a sensing potential of 0.70 V <span class="html-italic">vs.</span> Ag/AgCl/sat’d KCl.</p> Full article ">
167 KiB  
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 297 | Viewed by 21440
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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<p>The relationship of measurements, retrieval model and products at different scales.</p> Full article ">
924 KiB  
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 20 | Viewed by 14557
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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<p>(a) Location of the five study areas over a regional map. (b) MIVIS stripes acquired on the Arpi archaeological area (red box shows the study area), (c) (d) (e) (f) MIVIS images acquired over the Aquileia (resize of 755 × 920 pixels), Mothia (resize of 165 × 165), Marsala (resize of 330 × 330 pixels) and Selinunte (resize of 400 × 920 pixels) study areas, respectively (red box shows the study area).</p> Full article ">
<p>(a) Example of three test sites with the archaeological spectral anomalies (black arrow) detected on MIVIS imagery of Arpi (Italy). (b) SAM results for the same area (the yellow, green, grey, maroon colors depict the dry vegetation, photosynthetic green crop, artificial surfaces and bare soil, respectively). (c) LSU results for the three test sites (the brown color depicts the anomaly(1)-background system covered by more than 75 % of bare soil; the green color depicts the anomaly (2)-background system covered by more than 75 % of photosynthetic green crop; the yellow color shows the anomaly(3)-background system covered by a mixture of bare soil and green crop endmembers ranging between 25 % and 75 %). (d) MIVIS TIR image for the same test sites (MIVIS bands 93 only for visualization purposes).</p> Full article ">
<p>The graphs show the SI trend for the different MIVIS wavelength bands (VNIR, SWIR and TIR spectral regions) for all the test sites showing more than 75 % (from the unmixing results) of (a) green crop and (b) bare soil endmembers. Graph 4c shows the SI behaviour of a mixture of bare soil and green crop endmembers.</p> Full article ">
670 KiB  
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 72 | Viewed by 17332
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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<p>General location of study area: Ordos Plateau.</p> Full article ">
<p>Decision Tree for desertification assessment of temperate deciduous scrubs sub-region (landscape = 3) in August, 1990. “non”, “low”, “medium”, “high” and “severe” are used to represent desertification grades for short. NDVI, MSDI and albedo are the indicators used to build the rules.</p> Full article ">
<p>Desertification maps of Ordos in 1980 (a), 1990 (b) and 2000 (c).</p> Full article ">
<p>Statistics of the desertification area of Ordos in 1980, 1990 and 2000. “non”, “low”, “medium”, “high” and “severe” are used to represent desertification grades for short.</p> Full article ">
<p>The linear trend of aridity/humidity index in Ordos from 1980 to 1990 (a), from 1990 to 2000 (b); the change of rainfall (c) and temperature (d) in Ordos from 1980 to 2000.</p> Full article ">
<p>The change of livestock number <b>(</b>a) and the area of afforestation (b) in Ordos from 1980 to 2000.</p> Full article ">
1105 KiB  
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 16764
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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<p>The automobile lane detector integrated with CMOS imager for use in ITS.</p> Full article ">
<p>(a), (c), and (e) are the intensity profiles of the original image with pepper noise; and (b), (d), and (f) are the profiles without noise.</p> Full article ">
<p>A schematic form describes a hill associating with three variables, <span class="html-italic">Ps, Pe</span>, and <span class="html-italic">Pp</span>.</p> Full article ">
<p>The proposed architectural circuit (a) block diagram (b) signal flow diagram of the proposed mixed signal CMOS imager integrated with lane detection algorithm.</p> Full article ">
<p>Two types of pixel cell (a) normal cell (b) sampling cell.</p> Full article ">
<p>Layout of pixel cell (a) normal cell (b) sampling cell.</p> Full article ">
<p>Modified DFF with three extra transistors, M1, M2 and M3.</p> Full article ">
<p>Proposed analogue circuit of the dual 1-D Gaussian filters. The channel width ratio of transistors M4, M3, and M2 (or M7, M6, and M5) is 1:4:6, from right to left.</p> Full article ">
<p>The Proposed Peak-Finding and Lane-Point Allocation Modules.</p> Full article ">
381 KiB  
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 124 | Viewed by 16089
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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<p>Schematic diagram of MWCNT deposition on IDEs by ac dielectrophoresis.</p> Full article ">
<p>SEM image of a MWCNT network between interdigitated electrodes.</p> Full article ">
<p>Room-temperature resistance of a MWCNT network during ten repeated annealing cycles and the resistance recorded daily after annealing.</p> Full article ">
<p>Resistance-relative humidity data and linear fit of a MWCNT network obtained at room temperature.</p> Full article ">
<p>Time response and recovery curve of the MWCNT network from RH=25 % to 75 %.</p> Full article ">
<p>Temperature dependence of the resistance of the MWCNT network.</p> Full article ">
847 KiB  
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 15544
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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Graphical abstract

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<p>Image Generation Pipeline.</p> Full article ">
<p>Overall Filter Block Diagram.</p> Full article ">
<p>HVS curve used in the proposed approach.</p> Full article ">
<p>Filter Masks for Bayer Pattern Data.</p> Full article ">
<p>Green Texture Analyzer.</p> Full article ">
<p>Red/Blue texture analyzer.</p> Full article ">
<p>Texture Analyzer output: (a) input image after colour interpolation (b) gray-scale texture degree output: bright areas correspond to high frequency, dark areas correspond to low frequencies.</p> Full article ">
<p>The Wi coefficients weight the similarity degree between the central pixel and its neighborhood.</p> Full article ">
<p>Block diagram of the fuzzy computation process for determining the similarity weights between the central pixel and its N neighborhoods.</p> Full article ">
175 KiB  
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 15157
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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Graphical abstract
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<p>Block diagram of the system.</p> Full article ">
<p>Block diagram of the sensors heater voltage supplies.</p> Full article ">
<p>Acetone concentrations vs. sensor resistance for each sensor type.</p> Full article ">
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