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Sensors, Volume 9, Issue 11 (November 2009) , Pages 8382-9443

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Open AccessReview
Use of Biosensors as Alternatives to Current Regulatory Methods for Marine Biotoxins
Sensors 2009, 9(11), 9414-9443; https://doi.org/10.3390/s91109414
Received: 14 September 2009 / Revised: 27 October 2009 / Accepted: 28 October 2009 / Published: 24 November 2009
Cited by 25 | Viewed by 11813 | PDF Full-text (371 KB) | HTML Full-text | XML Full-text
Abstract
Marine toxins are currently monitored by means of a bioassay that requires the use of many mice, which poses a technical and ethical problem in many countries. With the exception of domoic acid, there is a legal requirement for the presence of other [...] Read more.
Marine toxins are currently monitored by means of a bioassay that requires the use of many mice, which poses a technical and ethical problem in many countries. With the exception of domoic acid, there is a legal requirement for the presence of other toxins (yessotoxin, saxitoxin and analogs, okadaic acid and analogs, pectenotoxins and azaspiracids) in seafood to be controlled by bioassay, but other toxins, such as palytoxin, cyclic imines, ciguatera and tetrodotoxin are potentially present in European food and there are no legal requirements or technical approaches available to identify their presence. The need for alternative methods to the bioassay is clearly important, and biosensors have become in recent years a feasible alternative to animal sacrifice. This review will discuss the advantages and disadvantages of using biosensors as alternatives to animal assays for marine toxins, with particular focus on surface plasmon resonance (SPR) technology. Full article
(This article belongs to the Special Issue Fluorescent Chemosensors)
Open AccessArticle
Field Performance of Nine Soil Water Content Sensors on a Sandy Loam Soil in New Brunswick, Maritime Region, Canada
Sensors 2009, 9(11), 9398-9413; https://doi.org/10.3390/s91109398
Received: 27 October 2009 / Revised: 10 November 2009 / Accepted: 16 November 2009 / Published: 24 November 2009
Cited by 17 | Viewed by 8939 | PDF Full-text (325 KB) | HTML Full-text | XML Full-text
Abstract
An in situ field test on nine commonly-used soil water sensors was carried out in a sandy loam soil located in the Potato Research Center, Fredericton, NB (Canada) using the gravimetric method as a reference. The results showed that among the tested sensors, [...] Read more.
An in situ field test on nine commonly-used soil water sensors was carried out in a sandy loam soil located in the Potato Research Center, Fredericton, NB (Canada) using the gravimetric method as a reference. The results showed that among the tested sensors, regardless of installation depths and soil water regimes, CS615, Trase, and Troxler performed the best with the factory calibrations, with a relative root mean square error (RRMSE) of 15.78, 16.93, and 17.65%, and a r2 of 0.75, 0.77, and 0.65, respectively. TRIME, Moisture Point (MP917), and Gopher performed slightly worse with the factory calibrations, with a RRMSE of 45.76, 26.57, and 20.41%, and a r2 of 0.65, 0.72, and 0.78, respectively, while the Gypsum, WaterMark, and Netafim showed a frequent need for calibration in the application in this region. Full article
(This article belongs to the Section Chemical Sensors)
Open AccessArticle
Improving Security for SCADA Sensor Networks with Reputation Systems and Self-Organizing Maps
Sensors 2009, 9(11), 9380-9397; https://doi.org/10.3390/s91109380
Received: 9 October 2009 / Revised: 30 October 2009 / Accepted: 4 November 2009 / Published: 20 November 2009
Cited by 22 | Viewed by 11157 | PDF Full-text (644 KB) | HTML Full-text | XML Full-text
Abstract
The reliable operation of modern infrastructures depends on computerized systems and Supervisory Control and Data Acquisition (SCADA) systems, which are also based on the data obtained from sensor networks. The inherent limitations of the sensor devices make them extremely vulnerable to cyberwarfare/cyberterrorism attacks. [...] Read more.
The reliable operation of modern infrastructures depends on computerized systems and Supervisory Control and Data Acquisition (SCADA) systems, which are also based on the data obtained from sensor networks. The inherent limitations of the sensor devices make them extremely vulnerable to cyberwarfare/cyberterrorism attacks. In this paper, we propose a reputation system enhanced with distributed agents, based on unsupervised learning algorithms (self-organizing maps), in order to achieve fault tolerance and enhanced resistance to previously unknown attacks. This approach has been extensively simulated and compared with previous proposals. Full article
(This article belongs to the Special Issue State-of-the-Art Sensors Technology in Spain)
Open AccessArticle
Segment Tracking via a Spatiotemporal Linking Process including Feedback Stabilization in an n-D Lattice Model
Sensors 2009, 9(11), 9355-9379; https://doi.org/10.3390/s91109355
Received: 7 August 2009 / Revised: 5 November 2009 / Accepted: 9 November 2009 / Published: 20 November 2009
Cited by 10 | Viewed by 9352 | PDF Full-text (1301 KB) | HTML Full-text | XML Full-text
Abstract
Model-free tracking is important for solving tasks such as moving-object tracking and action recognition in cases where no prior object knowledge is available. For this purpose, we extend the concept of spatially synchronous dynamics in spin-lattice models to the spatiotemporal domain to track [...] Read more.
Model-free tracking is important for solving tasks such as moving-object tracking and action recognition in cases where no prior object knowledge is available. For this purpose, we extend the concept of spatially synchronous dynamics in spin-lattice models to the spatiotemporal domain to track segments within an image sequence. The method is related to synchronization processes in neural networks and based on superparamagnetic clustering of data. Spin interactions result in the formation of clusters of correlated spins, providing an automatic labeling of corresponding image regions. The algorithm obeys detailed balance. This is an important property as it allows for consistent spin-transfer across subsequent frames, which can be used for segment tracking. Therefore, in the tracking process the correct equilibrium will always be found, which is an important advance as compared with other more heuristic tracking procedures. In the case of long image sequences, i.e., movies, the algorithm is augmented with a feedback mechanism, further stabilizing segment tracking. Full article
(This article belongs to the Special Issue Motion Detectors)
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Open AccessArticle
Synthesis and Characterization of Anti-HER2 Antibody Conjugated CdSe/CdZnS Quantum Dots for Fluorescence Imaging of Breast Cancer Cells
Sensors 2009, 9(11), 9332-9354; https://doi.org/10.3390/s91109332
Received: 21 September 2009 / Revised: 3 November 2009 / Accepted: 12 November 2009 / Published: 19 November 2009
Cited by 47 | Viewed by 13017 | PDF Full-text (3226 KB) | HTML Full-text | XML Full-text
Abstract
The early detection of HER2 (human epidermal growth factor receptor 2) status in breast cancer patients is very important for the effective implementation of anti-HER2 antibody therapy. Recently, HER2 detections using antibody conjugated quantum dots (QDs) have attracted much attention. QDs are a [...] Read more.
The early detection of HER2 (human epidermal growth factor receptor 2) status in breast cancer patients is very important for the effective implementation of anti-HER2 antibody therapy. Recently, HER2 detections using antibody conjugated quantum dots (QDs) have attracted much attention. QDs are a new class of fluorescent materials that have superior properties such as high brightness, high resistance to photo-bleaching, and multi-colored emission by a single-light source excitation. In this study, we synthesized three types of anti-HER2 antibody conjugated QDs (HER2Ab-QDs) using different coupling agents (EDC/sulfo-NHS, iminothiolane/sulfo-SMCC, and sulfo-SMCC). As water-soluble QDs for the conjugation of antibody, we used glutathione coated CdSe/CdZnS QDs (GSH-QDs) with fluorescence quantum yields of 0.23~0.39 in aqueous solution. Dispersibility, hydrodynamic size, and apparent molecular weights of the GSH-QDs and HER2Ab-QDs were characterized by using dynamic light scattering, fluorescence correlation spectroscopy, atomic force microscope, and size-exclusion HPLC. Fluorescence imaging of HER2 overexpressing cells (KPL-4 human breast cancer cell line) was performed by using HER2Ab-QDs as fluorescent probes. We found that the HER2Ab-QD prepared by using SMCC coupling with partially reduced antibody is a most effective probe for the detection of HER2 expression in KPL-4 cells. We have also studied the size dependency of HER2Ab-QDs (with green, orange, and red emission) on the fluorescence image of KPL-4 cells. Full article
(This article belongs to the Special Issue Fluorescent Chemosensors)
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Open AccessArticle
The Development of a Portable Hard Disk Encryption/Decryption System with a MEMS Coded Lock
Sensors 2009, 9(11), 9300-9331; https://doi.org/10.3390/s91109300
Received: 4 August 2009 / Revised: 8 October 2009 / Accepted: 12 November 2009 / Published: 19 November 2009
Cited by 7 | Viewed by 9889 | PDF Full-text (1243 KB) | HTML Full-text | XML Full-text
Abstract
In this paper, a novel portable hard-disk encryption/decryption system with a MEMS coded lock is presented, which can authenticate the user and provide the key for the AES encryption/decryption module. The portable hard-disk encryption/decryption system is composed of the authentication module, the USB [...] Read more.
In this paper, a novel portable hard-disk encryption/decryption system with a MEMS coded lock is presented, which can authenticate the user and provide the key for the AES encryption/decryption module. The portable hard-disk encryption/decryption system is composed of the authentication module, the USB portable hard-disk interface card, the ATA protocol command decoder module, the data encryption/decryption module, the cipher key management module, the MEMS coded lock controlling circuit module, the MEMS coded lock and the hard disk. The ATA protocol circuit, the MEMS control circuit and AES encryption/decryption circuit are designed and realized by FPGA(Field Programmable Gate Array). The MEMS coded lock with two couplers and two groups of counter-meshing-gears (CMGs) are fabricated by a LIGA-like process and precision engineering method. The whole prototype was fabricated and tested. The test results show that the user’s password could be correctly discriminated by the MEMS coded lock, and the AES encryption module could get the key from the MEMS coded lock. Moreover, the data in the hard-disk could be encrypted or decrypted, and the read-write speed of the dataflow could reach 17 MB/s in Ultra DMA mode. Full article
(This article belongs to the Special Issue Modeling, Testing and Reliability Issues in MEMS Engineering - 2009)
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Open AccessReview
Tiny Medicine: Nanomaterial-Based Biosensors
Sensors 2009, 9(11), 9275-9299; https://doi.org/10.3390/s91109275
Received: 10 October 2009 / Revised: 3 November 2009 / Accepted: 9 November 2009 / Published: 19 November 2009
Cited by 40 | Viewed by 13747 | PDF Full-text (1194 KB) | HTML Full-text | XML Full-text
Abstract
Tiny medicine refers to the development of small easy to use devices that can help in the early diagnosis and treatment of disease. Early diagnosis is the key to successfully treating many diseases. Nanomaterial-based biosensors utilize the unique properties of biological and physical [...] Read more.
Tiny medicine refers to the development of small easy to use devices that can help in the early diagnosis and treatment of disease. Early diagnosis is the key to successfully treating many diseases. Nanomaterial-based biosensors utilize the unique properties of biological and physical nanomaterials to recognize a target molecule and effect transduction of an electronic signal. In general, the advantages of nanomaterial-based biosensors are fast response, small size, high sensitivity, and portability compared to existing large electrodes and sensors. Systems integration is the core technology that enables tiny medicine. Integration of nanomaterials, microfluidics, automatic samplers, and transduction devices on a single chip provides many advantages for point of care devices such as biosensors. Biosensors are also being used as new analytical tools to study medicine. Thus this paper reviews how nanomaterials can be used to build biosensors and how these biosensors can help now and in the future to detect disease and monitor therapies. Full article
(This article belongs to the Section Biosensors)
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Open AccessArticle
A CMOS Time-Resolved Fluorescence Lifetime Analysis Micro-System
Sensors 2009, 9(11), 9255-9274; https://doi.org/10.3390/s91109255
Received: 2 September 2009 / Revised: 25 September 2009 / Accepted: 13 November 2009 / Published: 18 November 2009
Cited by 28 | Viewed by 11859 | PDF Full-text (3709 KB) | HTML Full-text | XML Full-text
Abstract
We describe a CMOS-based micro-system for time-resolved fluorescence lifetime analysis. It comprises a 16 × 4 array of single-photon avalanche diodes (SPADs) fabricated in 0.35 μm high-voltage CMOS technology with in-pixel time-gated photon counting circuitry and a second device incorporating an 8 × [...] Read more.
We describe a CMOS-based micro-system for time-resolved fluorescence lifetime analysis. It comprises a 16 × 4 array of single-photon avalanche diodes (SPADs) fabricated in 0.35 μm high-voltage CMOS technology with in-pixel time-gated photon counting circuitry and a second device incorporating an 8 × 8 AlInGaN blue micro-pixellated light-emitting diode (micro-LED) array bump-bonded to an equivalent array of LED drivers realized in a standard low-voltage 0.35 μm CMOS technology, capable of producing excitation pulses with a width of 777 ps (FWHM). This system replaces instrumentation based on lasers, photomultiplier tubes, bulk optics and discrete electronics with a PC-based micro-system. Demonstrator lifetime measurements of colloidal quantum dot and Rhodamine samples are presented. Full article
(This article belongs to the Special Issue Delft Workshop 2008-2009—Sensors and Imagers: a VLSI Perspective)
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Open AccessArticle
Trial of Multidisciplinary Observation at an Expandable Sub-Marine Cabled Station “Off-Hatsushima Island Observatory” in Sagami Bay, Japan
Sensors 2009, 9(11), 9241-9254; https://doi.org/10.3390/s91109241
Received: 25 September 2009 / Revised: 2 November 2009 / Accepted: 7 November 2009 / Published: 18 November 2009
Cited by 16 | Viewed by 9087 | PDF Full-text (1107 KB) | HTML Full-text | XML Full-text
Abstract
Sagami Bay is an active tectonic area in Japan. In 1993, a real-time deep sea floor observatory was deployed at 1,175 m depth about 7 km off Hatsushima Island, Sagami Bay to monitor seismic activities and other geophysical phenomena. Video cameras monitored biological [...] Read more.
Sagami Bay is an active tectonic area in Japan. In 1993, a real-time deep sea floor observatory was deployed at 1,175 m depth about 7 km off Hatsushima Island, Sagami Bay to monitor seismic activities and other geophysical phenomena. Video cameras monitored biological activities associated with tectonic activities. The observation system was renovated completely in 2000. An ocean bottom electromagnetic meter (OBEM), an ocean bottom differential pressure gauge (DPG) system, and an ocean bottom gravity meter (OBG) were installed January 2005; operations began in February of that year. An earthquake (M5.4) in April 2006, generated a submarine landslide that reached the Hatsushima Observatory, moving some sensors. The video camera took movies of mudflows; OBEM and other sensors detected distinctive changes occurring with the mudflow. Although the DPG and OBG were recovered in January 2008, the OBEM continues to obtain data. Full article
(This article belongs to the Special Issue State-of-the-Art Sensors Technology in Japan)
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Open AccessReview
Thin Magnetically Soft Wires for Magnetic Microsensors
Sensors 2009, 9(11), 9216-9240; https://doi.org/10.3390/s91109216
Received: 29 September 2009 / Revised: 9 November 2009 / Accepted: 11 November 2009 / Published: 18 November 2009
Cited by 122 | Viewed by 11388 | PDF Full-text (833 KB) | HTML Full-text | XML Full-text
Abstract
Recent advances in technology involving magnetic materials require development of novel advanced magnetic materials with improved magnetic and magneto-transport properties and with reduced dimensionality. Therefore magnetic materials with outstanding magnetic characteristics and reduced dimensionality have recently gained much attention. Among these magnetic materials [...] Read more.
Recent advances in technology involving magnetic materials require development of novel advanced magnetic materials with improved magnetic and magneto-transport properties and with reduced dimensionality. Therefore magnetic materials with outstanding magnetic characteristics and reduced dimensionality have recently gained much attention. Among these magnetic materials a family of thin wires with reduced geometrical dimensions (of order of 1–30 μm in diameter) have gained importance within the last few years. These thin wires combine excellent soft magnetic properties (with coercivities up to 4 A/m) with attractive magneto-transport properties (Giant Magneto-impedance effect, GMI, Giant Magneto-resistance effect, GMR) and an unusual re-magnetization process in positive magnetostriction compositions exhibiting quite fast domain wall propagation. In this paper we overview the magnetic and magneto-transport properties of these microwires that make them suitable for microsensor applications. Full article
(This article belongs to the Special Issue State-of-the-Art Sensors Technology in Spain)
Open AccessReview
Microfabricated Formaldehyde Gas Sensors
Sensors 2009, 9(11), 9196-9215; https://doi.org/10.3390/s91109196
Received: 27 September 2009 / Revised: 6 November 2009 / Accepted: 7 November 2009 / Published: 18 November 2009
Cited by 43 | Viewed by 12283 | PDF Full-text (632 KB) | HTML Full-text | XML Full-text
Abstract
Formaldehyde is a volatile organic compound that is widely used in textiles, paper, wood composites, and household materials. Formaldehyde will continuously outgas from manufactured wood products such as furniture, with adverse health effects resulting from prolonged low-level exposure. New, microfabricated sensors for formaldehyde [...] Read more.
Formaldehyde is a volatile organic compound that is widely used in textiles, paper, wood composites, and household materials. Formaldehyde will continuously outgas from manufactured wood products such as furniture, with adverse health effects resulting from prolonged low-level exposure. New, microfabricated sensors for formaldehyde have been developed to meet the need for portable, low-power gas detection. This paper reviews recent work including silicon microhotplates for metal oxide-based detection, enzyme-based electrochemical sensors, and nanowire-based sensors. This paper also investigates the promise of polymer-based sensors for low-temperature, low-power operation. Full article
(This article belongs to the Special Issue Gas Sensors 2009)
Open AccessArticle
An Immunity-Based Anomaly Detection System with Sensor Agents
Sensors 2009, 9(11), 9175-9195; https://doi.org/10.3390/s91109175
Received: 30 June 2009 / Revised: 5 November 2009 / Accepted: 9 November 2009 / Published: 18 November 2009
Cited by 6 | Viewed by 9008 | PDF Full-text (370 KB) | HTML Full-text | XML Full-text
Abstract
This paper proposes an immunity-based anomaly detection system with sensor agents based on the specificity and diversity of the immune system. Each agent is specialized to react to the behavior of a specific user. Multiple diverse agents decide whether the behavior is normal [...] Read more.
This paper proposes an immunity-based anomaly detection system with sensor agents based on the specificity and diversity of the immune system. Each agent is specialized to react to the behavior of a specific user. Multiple diverse agents decide whether the behavior is normal or abnormal. Conventional systems have used only a single sensor to detect anomalies, while the immunity-based system makes use of multiple sensors, which leads to improvements in detection accuracy. In addition, we propose an evaluation framework for the anomaly detection system, which is capable of evaluating the differences in detection accuracy between internal and external anomalies. This paper focuses on anomaly detection in user’s command sequences on UNIX-like systems. In experiments, the immunity-based system outperformed some of the best conventional systems. Full article
(This article belongs to the Special Issue State-of-the-Art Sensors Technology in Japan)
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Open AccessReview
Reporter Proteins in Whole-Cell Optical Bioreporter Detection Systems, Biosensor Integrations, and Biosensing Applications
Sensors 2009, 9(11), 9147-9174; https://doi.org/10.3390/s91109147
Received: 18 September 2009 / Revised: 14 October 2009 / Accepted: 23 October 2009 / Published: 17 November 2009
Cited by 44 | Viewed by 10888 | PDF Full-text (607 KB) | HTML Full-text | XML Full-text
Abstract
Whole-cell, genetically modified bioreporters are designed to emit detectable signals in response to a target analyte or related group of analytes. When integrated with a transducer capable of measuring those signals, a biosensor results that acts as a self-contained analytical system useful in [...] Read more.
Whole-cell, genetically modified bioreporters are designed to emit detectable signals in response to a target analyte or related group of analytes. When integrated with a transducer capable of measuring those signals, a biosensor results that acts as a self-contained analytical system useful in basic and applied environmental, medical, pharmacological, and agricultural sciences. Historically, these devices have focused on signaling proteins such as green fluorescent protein, aequorin, firefly luciferase, and/or bacterial luciferase. The biochemistry and genetic development of these sensor systems as well as the advantages, challenges, and common applications of each one will be discussed. Full article
(This article belongs to the Special Issue Microbial Sensors and Biosensors)
Open AccessArticle
Measuring Gait Using a Ground Laser Range Sensor
Sensors 2009, 9(11), 9133-9146; https://doi.org/10.3390/s91109133
Received: 7 August 2009 / Revised: 20 October 2009 / Accepted: 24 October 2009 / Published: 17 November 2009
Cited by 33 | Viewed by 9337 | PDF Full-text (288 KB) | HTML Full-text | XML Full-text
Abstract
This paper describes a measurement system designed to register the displacement of the legs using a two-dimensional laser range sensor with a scanning plane parallel to the ground and extract gait parameters. In the proposed methodology, the position of the legs is estimated [...] Read more.
This paper describes a measurement system designed to register the displacement of the legs using a two-dimensional laser range sensor with a scanning plane parallel to the ground and extract gait parameters. In the proposed methodology, the position of the legs is estimated by fitting two circles with the laser points that define their contour and the gait parameters are extracted applying a step-line model to the estimated displacement of the legs to reduce uncertainty in the determination of the stand and swing phase of the gait. Results obtained in a range up to 8 m shows that the systematic error in the location of one static leg is lower than 10 mm with and standard deviation lower than 8 mm; this deviation increases to 11 mm in the case of a moving leg. The proposed measurement system has been applied to estimate the gait parameters of six volunteers in a preliminary walking experiment. Full article
(This article belongs to the Special Issue Motion Detectors)
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Open AccessArticle
Electrosprayed Metal Oxide Semiconductor Films for Sensitive and Selective Detection of Hydrogen Sulfide
Sensors 2009, 9(11), 9122-9132; https://doi.org/10.3390/s91109122
Received: 13 October 2009 / Revised: 5 November 2009 / Accepted: 6 November 2009 / Published: 17 November 2009
Cited by 21 | Viewed by 10728 | PDF Full-text (526 KB) | HTML Full-text | XML Full-text
Abstract
Semiconductor metal oxide films of copper-doped tin oxide (Cu-SnO2), tungsten oxide (WO3) and indium oxide (In2O3) were deposited on a platinum coated alumina substrate employing the electrostatic spray deposition technique (ESD). The morphology studied with [...] Read more.
Semiconductor metal oxide films of copper-doped tin oxide (Cu-SnO2), tungsten oxide (WO3) and indium oxide (In2O3) were deposited on a platinum coated alumina substrate employing the electrostatic spray deposition technique (ESD). The morphology studied with scanning electron microscopy (SEM) and atomic force microscopy (AFM) shows porous homogeneous films comprising uniformly distributed aggregates of nano particles. The X-ray diffraction technique (XRD) proves the formation of crystalline phases with no impurities. Besides, the Raman cartographies provided information about the structural homogeneity. Some of the films are highly sensitive to low concentrations of H2S (10 ppm) at low operating temperatures (100 and 200 °C) and the best response in terms of Rair/Rgas is given by Cu-SnO2 films (2500) followed by WO3 (1200) and In2O3 (75). Moreover, all the films exhibit no cross-sensitivity to other reducing (SO2) or oxidizing (NO2) gases. Full article
(This article belongs to the Special Issue Gas Sensors 2009)
Open AccessArticle
Performance Characteristics of a PEM Fuel Cell with Parallel Flow Channels at Different Cathode Relative Humidity Levels
Sensors 2009, 9(11), 9104-9121; https://doi.org/10.3390/s91109104
Received: 26 August 2009 / Revised: 4 November 2009 / Accepted: 5 November 2009 / Published: 17 November 2009
Cited by 15 | Viewed by 11701 | PDF Full-text (1356 KB) | HTML Full-text | XML Full-text
Abstract
In fuel cells flow configuration and operating conditions such as cell temperature, humidity at each electrode and stoichiometric number are very crucial for improving performance. Too many flow channels could enhance the performance but result in high parasite loss. Therefore a trade-off between [...] Read more.
In fuel cells flow configuration and operating conditions such as cell temperature, humidity at each electrode and stoichiometric number are very crucial for improving performance. Too many flow channels could enhance the performance but result in high parasite loss. Therefore a trade-off between pressure drop and efficiency of a fuel cell should be considered for optimum design. This work focused on numerical simulation of the effects of operating conditions, especially cathode humidity, with simple micro parallel flow channels. It is known that the humidity at the cathode flow channel becomes very important for enhancing the ion conductivity of polymer membrane because fully humidified condition was normally set at anode. To investigate the effect of humidity on the performance of a fuel cell, in this study humidification was set to 100% at the anode flow channel and was changed by 0–100% at the cathode flow channel. Results showed that the maximum power density could be obtained under 60% humidified condition at the cathode where oxygen concentration was moderately high while maintaining high ion conductivity at a membrane. Full article
(This article belongs to the Special Issue Modeling, Testing and Reliability Issues in MEMS Engineering - 2009)
Open AccessArticle
Ferric Reducing Antioxidant Power and Square Wave Voltammetry for Assay of Low Molecular Weight Antioxidants in Blood Plasma: Performance and Comparison of Methods
Sensors 2009, 9(11), 9094-9103; https://doi.org/10.3390/s91109094
Received: 2 September 2009 / Revised: 7 October 2009 / Accepted: 22 October 2009 / Published: 17 November 2009
Cited by 40 | Viewed by 10815 | PDF Full-text (125 KB) | HTML Full-text | XML Full-text
Abstract
The purpose of the present study was to employ two methods—square wave voltammetry (SWV) performed on screen printed sensors and ferric reducing antioxidant power (FRAP)—as suitable tools for the assay of low-molecular-weight antioxidants (LMWAs). LMWAs were assayed by both methods and the resulting [...] Read more.
The purpose of the present study was to employ two methods—square wave voltammetry (SWV) performed on screen printed sensors and ferric reducing antioxidant power (FRAP)—as suitable tools for the assay of low-molecular-weight antioxidants (LMWAs). LMWAs were assayed by both methods and the resulting data were statistically compared. Plasma samples from five Cinereous vultures accidentally intoxicated with lead were used to represent real biological matrices with different levels of LMWAs. Blood was collected from the birds prior to and one month after treatment with Ca-EDTA. SWV resulted in two peaks. The first peak, with the potential value of 466 ± 15 mV, was recognized as ascorbic and uric acids, while the second one (743 ± 30 mV) represented glutathione, tocopherol, ascorbic acid and in a minor effect by uric acid, too. Contribution of individual antioxidants was recognized by separate assays of LMWA standards. Correlation between peaks 1 and 2 as well as the sum of the two peaks and FRAP was analysed. While peak 1 and the sum of peaks were in close correlation to FRAP results (correlation coefficient of 0.97), the relation between peak 2 and FRAP may be expressed using a correlation coefficient of 0.64. The determination of thiols by the Ellman assay confirmed the accuracy of SWV. Levels of glutathione and other similar structures were stable in the chosen model and it may be concluded that SWV is appropriate for assay of LMWAs in plasma samples. The methods employed in the study were advantageous in minimal sample volume consumption and fast acquisition of results. Full article
Open AccessReview
Implantable CMOS Biomedical Devices
Sensors 2009, 9(11), 9073-9093; https://doi.org/10.3390/s91109073
Received: 5 August 2009 / Revised: 6 November 2009 / Accepted: 9 November 2009 / Published: 17 November 2009
Cited by 59 | Viewed by 10445 | PDF Full-text (9350 KB) | HTML Full-text | XML Full-text
Abstract
The results of recent research on our implantable CMOS biomedical devices are reviewed. Topics include retinal prosthesis devices and deep-brain implantation devices for small animals. Fundamental device structures and characteristics as well as in vivo experiments are presented. Full article
(This article belongs to the Special Issue State-of-the-Art Sensors Technology in Japan)
Open AccessArticle
New Method for Estimation of Aeolian Sand Transport Rate Using Ceramic Sand Flux Sensor (UD-101)
Sensors 2009, 9(11), 9058-9072; https://doi.org/10.3390/s91109058
Received: 26 August 2009 / Revised: 4 November 2009 / Accepted: 5 November 2009 / Published: 13 November 2009
Cited by 19 | Viewed by 7807 | PDF Full-text (1487 KB) | HTML Full-text | XML Full-text
Abstract
In this study, a new method for the estimation of aeolian sand transport rate was developed; the method employs a ceramic sand flux sensor (UD-101). UD-101 detects wind-blown sand impacting on its surface. The method was devised by considering the results of wind [...] Read more.
In this study, a new method for the estimation of aeolian sand transport rate was developed; the method employs a ceramic sand flux sensor (UD-101). UD-101 detects wind-blown sand impacting on its surface. The method was devised by considering the results of wind tunnel experiments that were performed using a vertical sediment trap and the UD-101. Field measurements to evaluate the estimation accuracy during the prevalence of unsteady winds were performed on a flat backshore. The results showed that aeolian sand transport rates estimated using the developed method were of the same order as those estimated using the existing method for high transport rates, i.e., for transport rates greater than 0.01 kg m–1 s–1. Full article
(This article belongs to the Special Issue State-of-the-Art Sensors Technology in Japan)
Open AccessArticle
Recent Developments of an Opto-Electronic THz Spectrometer for High-Resolution Spectroscopy
Sensors 2009, 9(11), 9039-9057; https://doi.org/10.3390/s91109039
Received: 21 September 2009 / Revised: 13 October 2009 / Accepted: 29 October 2009 / Published: 13 November 2009
Cited by 22 | Viewed by 9891 | PDF Full-text (1016 KB) | HTML Full-text | XML Full-text
Abstract
A review is provided of sources and detectors that can be employed in the THz range before the description of an opto-electronic source of monochromatic THz radiation. The realized spectrometer has been applied to gas phase spectroscopy. Air-broadening coefficients of HCN are determined [...] Read more.
A review is provided of sources and detectors that can be employed in the THz range before the description of an opto-electronic source of monochromatic THz radiation. The realized spectrometer has been applied to gas phase spectroscopy. Air-broadening coefficients of HCN are determined and the insensitivity of this technique to aerosols is demonstrated by the analysis of cigarette smoke. A multiple pass sample cell has been used to obtain a sensitivity improvement allowing transitions of the volatile organic compounds to be observed. A solution to the frequency metrology is presented and promises to yield accurate molecular line center measurements. Full article
(This article belongs to the Special Issue Laser Spectroscopy and Sensing)
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Open AccessArticle
Selective Detection of Formaldehyde Gas Using a Cd-Doped TiO2-SnO2 Sensor
Sensors 2009, 9(11), 9029-9038; https://doi.org/10.3390/s91109029
Received: 9 October 2009 / Revised: 28 October 2009 / Accepted: 29 October 2009 / Published: 13 November 2009
Cited by 98 | Viewed by 9991 | PDF Full-text (375 KB) | HTML Full-text | XML Full-text
Abstract
We report the microstructure and gas-sensing properties of a nonequilibrium TiO2-SnO2 solid solution prepared by the sol-gel method. In particular, we focus on the effect of Cd doping on the sensing behavior of the TiO2-SnO2 sensor. Of [...] Read more.
We report the microstructure and gas-sensing properties of a nonequilibrium TiO2-SnO2 solid solution prepared by the sol-gel method. In particular, we focus on the effect of Cd doping on the sensing behavior of the TiO2-SnO2 sensor. Of all volatile organic compound gases examined, the sensor with Cd doping exhibits exclusive selectivity as well as high sensitivity to formaldehyde, a main harmful indoor gas. The key gas-sensing quantities, maximum sensitivity, optimal working temperature, and response and recovery time, are found to meet the basic industrial needs. This makes the Cd-doped TiO2-SnO2 composite a promising sensor material for detecting the formaldehyde gas. Full article
(This article belongs to the Special Issue Gas Sensors 2009)
Open AccessArticle
Testing Multivariate Adaptive Regression Splines (MARS) as a Method of Land Cover Classification of TERRA-ASTER Satellite Images
Sensors 2009, 9(11), 9011-9028; https://doi.org/10.3390/s91109011
Received: 24 September 2009 / Revised: 1 November 2009 / Accepted: 2 November 2009 / Published: 13 November 2009
Cited by 21 | Viewed by 8583 | PDF Full-text (639 KB) | HTML Full-text | XML Full-text
Abstract
This work proposes a new method to classify multi-spectral satellite images based on multivariate adaptive regression splines (MARS) and compares this classification system with the more common parallelepiped and maximum likelihood (ML) methods. We apply the classification methods to the land cover classification [...] Read more.
This work proposes a new method to classify multi-spectral satellite images based on multivariate adaptive regression splines (MARS) and compares this classification system with the more common parallelepiped and maximum likelihood (ML) methods. We apply the classification methods to the land cover classification of a test zone located in southwestern Spain. The basis of the MARS method and its associated procedures are explained in detail, and the area under the ROC curve (AUC) is compared for the three methods. The results show that the MARS method provides better results than the parallelepiped method in all cases, and it provides better results than the maximum likelihood method in 13 cases out of 17. These results demonstrate that the MARS method can be used in isolation or in combination with other methods to improve the accuracy of soil cover classification. The improvement is statistically significant according to the Wilcoxon signed rank test. Full article
(This article belongs to the Special Issue State-of-the-Art Sensors Technology in Spain)
Open AccessArticle
H2 Sensing Response of Flame-spray-made Ru/SnO2 Thick Films Fabricated from Spin-Coated Nanoparticles
Sensors 2009, 9(11), 8996-9010; https://doi.org/10.3390/s91108996
Received: 7 August 2009 / Revised: 21 October 2009 / Accepted: 22 October 2009 / Published: 11 November 2009
Cited by 38 | Viewed by 9094 | PDF Full-text (1365 KB) | HTML Full-text | XML Full-text
Abstract
High specific surface area (SSABET: 141.6 m2/g) SnO2 nanoparticles doped with 0.2–3 wt% Ru were successfully produced in a single step by flame spray pyrolysis (FSP). The phase and crystallite size were analyzed by XRD. The specific [...] Read more.
High specific surface area (SSABET: 141.6 m2/g) SnO2 nanoparticles doped with 0.2–3 wt% Ru were successfully produced in a single step by flame spray pyrolysis (FSP). The phase and crystallite size were analyzed by XRD. The specific surface area (SSABET) of the nanoparticles was measured by nitrogen adsorption (BET analysis). As the Ru concentration increased, the SSABET was found to linearly decrease, while the average BET-equivalent particle diameter (dBET) increased. FSP yielded small Ru particles attached to the surface of the supporting SnO2 nanoparticles, indicating a high SSABET. The morphology and accurate size of the primary particles were further investigated by TEM. The crystallite sizes of the spherical, hexagonal, and rectangular SnO2 particles were in the range of 3–10 nm. SnO2 nanorods were found to range from 3–5 nm in width and 5–20 nm in length. Sensing films were prepared by the spin coating technique. The gas sensing of H2 (500–10,000 ppm) was studied at the operating temperatures ranging from 200–350 °C in presence of dry air. After the sensing tests, the morphology and the cross-section of sensing film were analyzed by SEM and EDS analyses. The 0.2%Ru-dispersed on SnO2 sensing film showed the highest sensitivity and a very fast response time (6 s) compared to a pure SnO2 sensing film, with a highest H2 concentration of 1 vol% at 350 °C and a low H2 detection limit of 500 ppm at 200 °C. Full article
(This article belongs to the Special Issue Gas Sensors 2009)
Open AccessArticle
Autonomous Distributed Self-Organization for Mobile Wireless Sensor Networks
Sensors 2009, 9(11), 8961-8995; https://doi.org/10.3390/s91108961
Received: 9 June 2009 / Revised: 18 October 2009 / Accepted: 20 October 2009 / Published: 11 November 2009
Cited by 3 | Viewed by 7490 | PDF Full-text (623 KB) | HTML Full-text | XML Full-text
Abstract
This paper presents an adaptive combined-metrics-based clustering scheme for mobile wireless sensor networks, which manages the mobile sensors by utilizing the hierarchical network structure and allocates network resources efficiently. A local criteria is used to help mobile sensors form a new cluster or [...] Read more.
This paper presents an adaptive combined-metrics-based clustering scheme for mobile wireless sensor networks, which manages the mobile sensors by utilizing the hierarchical network structure and allocates network resources efficiently. A local criteria is used to help mobile sensors form a new cluster or join a current cluster. The messages transmitted during hierarchical clustering are applied to choose distributed gateways such that communication for adjacent clusters and distributed topology control can be achieved. In order to balance the load among clusters and govern the topology change, a cluster reformation scheme using localized criterions is implemented. The proposed scheme is simulated and analyzed to abstract the network behaviors in a number of settings. The experimental results show that the proposed algorithm provides efficient network topology management and achieves high scalability in mobile sensor networks. Full article
(This article belongs to the Special Issue Sensor Configuration and Smart Sensors)
Open AccessArticle
A Novel Neural Network-Based Technique for Smart Gas Sensors Operating in a Dynamic Environment
Sensors 2009, 9(11), 8944-8960; https://doi.org/10.3390/s91108944
Received: 9 September 2009 / Revised: 27 October 2009 / Accepted: 30 October 2009 / Published: 11 November 2009
Cited by 22 | Viewed by 8778 | PDF Full-text (1028 KB) | HTML Full-text | XML Full-text
Abstract
Thanks to their high sensitivity and low-cost, metal oxide gas sensors (MOX) are widely used in gas detection, although they present well-known problems (lack of selectivity and environmental effects…). We present in this paper a novel neural network- based technique to remedy these [...] Read more.
Thanks to their high sensitivity and low-cost, metal oxide gas sensors (MOX) are widely used in gas detection, although they present well-known problems (lack of selectivity and environmental effects…). We present in this paper a novel neural network- based technique to remedy these problems. The idea is to create intelligent models; the first one, called corrector, can automatically linearize a sensor’s response characteristics and eliminate its dependency on the environmental parameters. The corrector’s responses are processed with the second intelligent model which has the role of discriminating exactly the detected gas (nature and concentration). The gas sensors used are industrial resistive kind (TGS8xx, by Figaro Engineering). The MATLAB environment is used during the design phase and optimization. The sensor models, the corrector, and the selective model were implemented and tested in the PSPICE simulator. The sensor model accurately expresses the nonlinear character of the response and the dependence on temperature and relative humidity in addition to their gas nature dependency. The corrector linearizes and compensates the sensor’s responses. The method discriminates qualitatively and quantitatively between seven gases. The advantage of the method is that it uses a small representative database so we can easily implement the model in an electrical simulator. This method can be extended to other sensors. Full article
(This article belongs to the Special Issue Gas Sensors 2009)
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Open AccessArticle
A Robust Head Tracking System Based on Monocular Vision and Planar Templates
Sensors 2009, 9(11), 8924-8943; https://doi.org/10.3390/s91108924
Received: 7 September 2009 / Revised: 9 October 2009 / Accepted: 15 October 2009 / Published: 11 November 2009
Cited by 3 | Viewed by 9565 | PDF Full-text (14844 KB) | HTML Full-text | XML Full-text
Abstract
This paper details the implementation of a head tracking system suitable for its use in teleoperation stations or control centers, taking into account the limitations and constraints usually associated to those environments. The paper discusses and justifies the selection of the different methods [...] Read more.
This paper details the implementation of a head tracking system suitable for its use in teleoperation stations or control centers, taking into account the limitations and constraints usually associated to those environments. The paper discusses and justifies the selection of the different methods and sensors to build the head tracking system, detailing also the processing steps of the system in operation. A prototype to validate the proposed approach is also presented along with several tests in a real environment with promising results. Full article
(This article belongs to the Special Issue State-of-the-Art Sensors Technology in Spain)
Open AccessCommunication
Miniaturized pH Sensors Based on Zinc Oxide Nanotubes/Nanorods
Sensors 2009, 9(11), 8911-8923; https://doi.org/10.3390/s91108911
Received: 22 September 2009 / Revised: 19 October 2009 / Accepted: 19 October 2009 / Published: 9 November 2009
Cited by 82 | Viewed by 14638 | PDF Full-text (4689 KB) | HTML Full-text | XML Full-text
Abstract
ZnO nanotubes and nanorods grown on gold thin film were used to create pH sensor devices. The developed ZnO nanotube and nanorod pH sensors display good reproducibility, repeatability and long-term stability and exhibit a pH-dependent electrochemical potential difference versus an Ag/AgCl reference electrode [...] Read more.
ZnO nanotubes and nanorods grown on gold thin film were used to create pH sensor devices. The developed ZnO nanotube and nanorod pH sensors display good reproducibility, repeatability and long-term stability and exhibit a pH-dependent electrochemical potential difference versus an Ag/AgCl reference electrode over a large dynamic pH range. We found the ZnO nanotubes provide sensitivity as high as twice that of the ZnO nanorods, which can be ascribed to the fact that small dimensional ZnO nanotubes have a higher level of surface and subsurface oxygen vacancies and provide a larger effective surface area with higher surface-to-volume ratio as compared to ZnO nanorods, thus affording the ZnO nanotube pH sensor a higher sensitivity. Experimental results indicate ZnO nanotubes can be used in pH sensor applications with improved performance. Moreover, the ZnO nanotube arrays may find potential application as a novel material for measurements of intracellular biochemical species within single living cells. Full article
(This article belongs to the Special Issue Metal-Oxide Based Nanosensors)
Open AccessEditorial
Editorial: Nanotechnological Advances in Biosensors
Sensors 2009, 9(11), 8907-8910; https://doi.org/10.3390/s91108907
Received: 18 September 2009 / Accepted: 9 November 2009 / Published: 9 November 2009
Cited by 4 | Viewed by 9234 | PDF Full-text (28 KB) | HTML Full-text | XML Full-text
Abstract
A biosensor is a physicochemical or hybrid physical-chemical-biological device that detects a biological molecule, organism, or process. Because of the nature of their targets, biosensors need to be faster, smaller, more sensitive, and more specific than nearly all of their physicochemical counterparts or [...] Read more.
A biosensor is a physicochemical or hybrid physical-chemical-biological device that detects a biological molecule, organism, or process. Because of the nature of their targets, biosensors need to be faster, smaller, more sensitive, and more specific than nearly all of their physicochemical counterparts or the traditional methods that they are designed to replace. Speed is of the essence in medical diagnosis as it permits for rapid, accurate treatment and does not allow patients to be lost to follow-up. Small size and greater sensitivity mean less-invasive sampling and detection of molecules such as neurotransmitters or hormones at biologically-relevant levels. Greater specificity allows assays to be performed in complex fluids such as blood or urine without false negative or false positive results. [...] Full article
(This article belongs to the Special Issue Nanotechnological Advances in Biosensors)
Open AccessArticle
Sensor for Distance Measurement Using Pixel Grey-Level Information
Sensors 2009, 9(11), 8896-8906; https://doi.org/10.3390/s91108896
Received: 30 September 2009 / Revised: 29 October 2009 / Accepted: 4 November 2009 / Published: 6 November 2009
Cited by 6 | Viewed by 8684 | PDF Full-text (303 KB) | HTML Full-text | XML Full-text
Abstract
An alternative method for distance measurement is presented, based on a radiometric approach to the image formation process. The proposed methodology uses images from an infrared emitting diode (IRED) to estimate the distance between the camera and the IRED. Camera output grey-level intensities [...] Read more.
An alternative method for distance measurement is presented, based on a radiometric approach to the image formation process. The proposed methodology uses images from an infrared emitting diode (IRED) to estimate the distance between the camera and the IRED. Camera output grey-level intensities are a function of the accumulated image irradiance, which is also related by inverse distance square law to the distance between the camera and the IRED. Analyzing camera-IRED distance, magnitudes that affected image grey-level intensities, and therefore accumulated image irradiance, were integrated into a differential model which was calibrated and used for distance estimation over a 200 to 600 cm range. In a preliminary model, the camera and the emitter were aligned. Full article
(This article belongs to the Special Issue State-of-the-Art Sensors Technology in Spain)
Open AccessArticle
Resistive Oxygen Sensor Using Ceria-Zirconia Sensor Material and Ceria-Yttria Temperature Compensating Material for Lean-Burn Engine
Sensors 2009, 9(11), 8884-8895; https://doi.org/10.3390/s91108884
Received: 14 September 2009 / Revised: 13 October 2009 / Accepted: 2 November 2009 / Published: 5 November 2009
Cited by 16 | Viewed by 9470 | PDF Full-text (587 KB) | HTML Full-text | XML Full-text
Abstract
Temperature compensating materials were investigated for a resistive oxygen sensor using Ce0.9Zr0.1O2 as a sensor material for lean-burn engines. The temperature dependence of a temperature compensating material should be the same as the sensor material; therefore, the Y [...] Read more.
Temperature compensating materials were investigated for a resistive oxygen sensor using Ce0.9Zr0.1O2 as a sensor material for lean-burn engines. The temperature dependence of a temperature compensating material should be the same as the sensor material; therefore, the Y concentration in CeO2-Y2O3 was optimized. The resistance of Ce0.5Y0.5O2-δ was independent of the air-to-fuel ratio (oxygen partial pressure), so that it was confirmed to function as a temperature compensating material. Sensor elements comprised of Ce0.9Zr0.1O2 and Ce0.5Y0.5O2-δ were fabricated and the output was determined to be approximately independent of the temperature in the wide range from 773 to 1,073 K. Full article
(This article belongs to the Section Chemical Sensors)
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