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Sensors, Volume 10, Issue 7 (July 2010), Pages 6275-7066

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Open AccessCommunication Two-channel Hyperspectral LiDAR with a Supercontinuum Laser Source
Sensors 2010, 10(7), 7057-7066; https://doi.org/10.3390/s100707057
Received: 18 June 2010 / Revised: 15 July 2010 / Accepted: 19 July 2010 / Published: 23 July 2010
Cited by 55 | PDF Full-text (391 KB) | HTML Full-text | XML Full-text
Abstract
Recent advances in nonlinear fiber optics and compact pulsed lasers have resulted in creation of broadband directional light sources. These supercontinuum laser sources produce directional broadband light using cascaded nonlinear optical interactions in an optical fibre framework. This system is used to simultaneously
[...] Read more.
Recent advances in nonlinear fiber optics and compact pulsed lasers have resulted in creation of broadband directional light sources. These supercontinuum laser sources produce directional broadband light using cascaded nonlinear optical interactions in an optical fibre framework. This system is used to simultaneously measure distance and reflectance to demonstrate a technique capable of distinguishing between a vegetation target and inorganic material using the Normalized Difference Vegetation Index (NDVI) parameters, while the range can be obtained from the waveform of the echoes. A two-channel, spectral range-finding system based on a supercontinuum laser source was used to determine its potential application of distinguishing the NDVI for Norway spruce, a coniferous tree, and its three-dimensional parameters at 600 nm and 800 nm. A prototype system was built using commercial components. Full article
(This article belongs to the Section Remote Sensors)
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Open AccessArticle Investigation of the Frequency Shift of a SAD Circuit Loop and the Internal Micro-Cantilever in a Gas Sensor
Sensors 2010, 10(7), 7044-7056; https://doi.org/10.3390/s100707044
Received: 15 June 2010 / Revised: 30 June 2010 / Accepted: 10 July 2010 / Published: 23 July 2010
Cited by 4 | PDF Full-text (426 KB) | HTML Full-text | XML Full-text
Abstract
Micro-cantilever sensors for mass detection using resonance frequency have attracted considerable attention over the last decade in the field of gas sensing. For such a sensing system, an oscillator circuit loop is conventionally used to actuate the micro-cantilever, and trace the frequency shifts.
[...] Read more.
Micro-cantilever sensors for mass detection using resonance frequency have attracted considerable attention over the last decade in the field of gas sensing. For such a sensing system, an oscillator circuit loop is conventionally used to actuate the micro-cantilever, and trace the frequency shifts. In this paper, gas experiments are introduced to investigate the mechanical resonance frequency shifts of the micro-cantilever within the circuit loop(mechanical resonance frequency, MRF) and resonating frequency shifts of the electric signal in the oscillator circuit (system working frequency, SWF). A silicon beam with a piezoelectric zinc oxide layer is employed in the experiment, and a Self-Actuating-Detecting (SAD) circuit loop is built to drive the micro-cantilever and to follow the frequency shifts. The differences between the two resonating frequencies and their shifts are discussed and analyzed, and a coefficientrelated to the two frequency shifts is confirmed.Micro-cantilever sensors for mass detection using resonance frequency have attracted considerable attention over the last decade in the field of gas sensing. For such a sensing system, an oscillator circuit loop is conventionally used to actuate the micro-cantilever, and trace the frequency shifts. In this paper, gas experiments are introduced to investigate the mechanical resonance frequency shifts of the micro-cantilever within the circuit loop(mechanical resonance frequency, MRF) and resonating frequency shifts of the electric signal in the oscillator circuit (system working frequency, SWF). A silicon beam with a piezoelectric zinc oxide layer is employed in the experiment, and a Self-Actuating-Detecting (SAD) circuit loop is built to drive the micro-cantilever and to follow the frequency shifts. The differences between the two resonating frequencies and their shifts are discussed and analyzed, and a coefficientrelated to the two frequency shifts is confirmed. Full article
(This article belongs to the Special Issue Intelligent Sensors - 2010)
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Open AccessReview Fluorescent Chemosensors for Toxic Organophosphorus Pesticides: A Review
Sensors 2010, 10(7), 7018-7043; https://doi.org/10.3390/s100707018
Received: 24 March 2010 / Revised: 12 April 2010 / Accepted: 24 June 2010 / Published: 21 July 2010
Cited by 63 | PDF Full-text (1408 KB) | HTML Full-text | XML Full-text
Abstract
Many organophosphorus (OP) based compounds are highly toxic and powerful inhibitors of cholinesterases that generate serious environmental and human health concerns. Organothiophosphates with a thiophosphoryl (P=S) functional group constitute a broad class of these widely used pesticides. They are related to the more
[...] Read more.
Many organophosphorus (OP) based compounds are highly toxic and powerful inhibitors of cholinesterases that generate serious environmental and human health concerns. Organothiophosphates with a thiophosphoryl (P=S) functional group constitute a broad class of these widely used pesticides. They are related to the more reactive phosphoryl (P=O) organophosphates, which include very lethal nerve agents and chemical warfare agents, such as, VX, Soman and Sarin. Unfortunately, widespread and frequent commercial use of OP-based compounds in agricultural lands has resulted in their presence as residues in crops, livestock, and poultry products and also led to their migration into aquifers. Thus, the design of new sensors with improved analyte selectivity and sensitivity is of paramount importance in this area. Herein, we review recent advances in the development of fluorescent chemosensors for toxic OP pesticides and related compounds. We also discuss challenges and progress towards the design of future chemosensors with dual modes for signal transduction. Full article
(This article belongs to the Special Issue Fluorescent Chemosensors)
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Open AccessArticle The Effects of the Location of Au Additives on Combustion-generated SnO2 Nanopowders for CO Gas Sensing
Sensors 2010, 10(7), 7002-7017; https://doi.org/10.3390/s100707002
Received: 9 June 2010 / Revised: 16 July 2010 / Accepted: 19 July 2010 / Published: 21 July 2010
Cited by 26 | PDF Full-text (1288 KB) | HTML Full-text | XML Full-text
Abstract
The current work presents the results of an experimental study of the effects of the location of gold additives on the performance of combustion-generated tin dioxide (SnO2) nanopowders in solid state gas sensors. The time response and sensor response
to 500
[...] Read more.
The current work presents the results of an experimental study of the effects of the location of gold additives on the performance of combustion-generated tin dioxide (SnO2) nanopowders in solid state gas sensors. The time response and sensor response
to 500 ppm carbon monoxide is reported for a range of gold additive/SnO2 film architectures including the use of colloidal, sputtered, and combustion-generated Au additives. The opportunities afforded by combustion synthesis to affect the SnO2/additive morphology are demonstrated. The best sensor performance in terms of sensor response (S) and time response (t) was observed when the Au additives were restricted to the outermost layer of the gas-sensing film. Further improvement was observed in the sensor response and time response when the Au additives were dispersed throughout the outermost layer of the film, where S = 11.3 and t = 51 s, as opposed to Au localized at the surface, where
S = 6.1 and t = 60 s. Full article
(This article belongs to the Special Issue Gas Sensors - 2010)
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Open AccessArticle L Band Brightness Temperature Observations over a Corn Canopy during the Entire Growth Cycle
Sensors 2010, 10(7), 6980-7001; https://doi.org/10.3390/s100706980
Received: 26 March 2010 / Revised: 11 June 2010 / Accepted: 11 June 2010 / Published: 20 July 2010
Cited by 4 | PDF Full-text (1196 KB) | HTML Full-text | XML Full-text
Abstract
During a field campaign covering the 2002 corn growing season, a dual polarized tower mounted L-band (1.4 GHz) radiometer (LRAD) provided brightness temperature (TB) measurements at preset intervals, incidence and azimuth angles. These radiometer measurements were supported by an extensive
[...] Read more.
During a field campaign covering the 2002 corn growing season, a dual polarized tower mounted L-band (1.4 GHz) radiometer (LRAD) provided brightness temperature (TB) measurements at preset intervals, incidence and azimuth angles. These radiometer measurements were supported by an extensive characterization of land surface variables including soil moisture, soil temperature, vegetation biomass, and surface roughness. In the period May 22 to August 30, ten days of radiometer and ground measurements are available for a corn canopy with a vegetation water content (W) range of 0.0 to 4.3 kg m−2. Using this data set, the effects of corn vegetation on surface emissions are investigated by means of a semi-empirical radiative transfer model. Additionally, the impact of roughness on the surface emission is quantified using TB measurements over bare soil conditions. Subsequently, the estimated roughness parameters, ground measurements and horizontally OPEN ACCESS (H)-polarized TB are employed to invert the H-polarized transmissivity (γh) for the monitored corn growing season. Full article
(This article belongs to the Section Remote Sensors)
Open AccessArticle Exploiting the Autofluorescent Properties of Photosynthetic Pigments for Analysis of Pigmentation and Morphology in Live Fremyella diplosiphon Cells
Sensors 2010, 10(7), 6969-6979; https://doi.org/10.3390/s100706969
Received: 7 June 2010 / Revised: 12 July 2010 / Accepted: 16 July 2010 / Published: 19 July 2010
Cited by 18 | PDF Full-text (343 KB) | HTML Full-text | XML Full-text
Abstract
Fremyella diplosiphon is a freshwater, filamentous cyanobacterium that exhibits light-dependent regulation of photosynthetic pigment accumulation and cellular and filament morphologies in a well-known process known as complementary chromatic adaptation (CCA). One of the techniques used to investigate the molecular bases of distinct aspects
[...] Read more.
Fremyella diplosiphon is a freshwater, filamentous cyanobacterium that exhibits light-dependent regulation of photosynthetic pigment accumulation and cellular and filament morphologies in a well-known process known as complementary chromatic adaptation (CCA). One of the techniques used to investigate the molecular bases of distinct aspects of CCA is confocal laser scanning microscopy (CLSM). CLSM capitalizes on the autofluorescent properties of cyanobacterial phycobiliproteins and chlorophyll a. We employed CLSM to perform spectral scanning analyses of F. diplosiphon strains grown under distinct light conditions. We report optimized utilization of CLSM to elucidate the molecular basis of the photoregulation of pigment accumulation and morphological responses in F. diplosiphon. Full article
(This article belongs to the Special Issue Photodetectors and Imaging Technologies)
Open AccessReview Wireless Sensor Networks for Oceanographic Monitoring: A Systematic Review
Sensors 2010, 10(7), 6948-6968; https://doi.org/10.3390/s100706948
Received: 11 June 2010 / Revised: 29 June 2010 / Accepted: 1 July 2010 / Published: 19 July 2010
Cited by 67 | PDF Full-text (858 KB) | HTML Full-text | XML Full-text
Abstract
Monitoring of the marine environment has come to be a field of scientific interest in the last ten years. The instruments used in this work have ranged from small-scale sensor networks to complex observation systems. Among small-scale networks, Wireless Sensor Networks (WSNs) are
[...] Read more.
Monitoring of the marine environment has come to be a field of scientific interest in the last ten years. The instruments used in this work have ranged from small-scale sensor networks to complex observation systems. Among small-scale networks, Wireless Sensor Networks (WSNs) are a highly attractive solution in that they are easy to deploy, operate and dismantle and are relatively inexpensive. The aim of this paper is to identify, appraise, select and synthesize all high quality research evidence relevant to the use of WSNs in oceanographic monitoring. The literature is systematically reviewed to offer an overview of the present state of this field of study and identify the principal resources that have been used to implement networks of this kind. Finally, this article details the challenges and difficulties that have to be overcome if these networks are to be successfully deployed. Full article
(This article belongs to the Section Chemical Sensors)
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Open AccessReview Position and Speed Control of Brushless DC Motors Using Sensorless Techniques and Application Trends
Sensors 2010, 10(7), 6901-6947; https://doi.org/10.3390/s100706901
Received: 10 June 2010 / Revised: 30 June 2010 / Accepted: 5 July 2010 / Published: 19 July 2010
Cited by 72 | PDF Full-text (2283 KB) | HTML Full-text | XML Full-text
Abstract
This paper provides a technical review of position and speed sensorless methods for controlling Brushless Direct Current (BLDC) motor drives, including the background analysis using sensors, limitations and advances. The performance and reliability of BLDC motor drivers have been improved because the conventional
[...] Read more.
This paper provides a technical review of position and speed sensorless methods for controlling Brushless Direct Current (BLDC) motor drives, including the background analysis using sensors, limitations and advances. The performance and reliability of BLDC motor drivers have been improved because the conventional control and sensing techniques have been improved through sensorless technology. Then, in this paper sensorless advances are reviewed and recent developments in this area are introduced with their inherent advantages and drawbacks, including the analysis of practical implementation issues and applications. The study includes a deep overview of state-of-the-art back-EMF sensing methods, which includes Terminal Voltage Sensing, Third Harmonic Voltage Integration, Terminal Current Sensing, Back-EMF Integration and PWM strategies. Also, the most relevant techniques based on estimation and models are briefly analysed, such as Sliding-mode Observer, Extended Kalman Filter, Model Reference Adaptive System, Adaptive observers (Full-order and Pseudoreduced-order) and Artificial Neural Networks. Full article
(This article belongs to the Section Chemical Sensors)
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Open AccessReview Quantum Cascade Laser Absorption Spectroscopy as a Plasma Diagnostic Tool: An Overview
Sensors 2010, 10(7), 6861-6900; https://doi.org/10.3390/s100706861
Received: 8 June 2010 / Revised: 25 June 2010 / Accepted: 10 July 2010 / Published: 16 July 2010
Cited by 39 | PDF Full-text (1025 KB) | HTML Full-text | XML Full-text
Abstract
The recent availability of thermoelectrically cooled pulsed and continuous wave quantum and inter-band cascade lasers in the mid-infrared spectral region has led to significant improvements and new developments in chemical sensing techniques using in-situ laser absorption spectroscopy for plasma diagnostic purposes. The aim
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The recent availability of thermoelectrically cooled pulsed and continuous wave quantum and inter-band cascade lasers in the mid-infrared spectral region has led to significant improvements and new developments in chemical sensing techniques using in-situ laser absorption spectroscopy for plasma diagnostic purposes. The aim of this article is therefore two-fold: (i) to summarize the challenges which arise in the application of quantum cascade lasers in such environments, and, (ii) to provide an overview of recent spectroscopic results (encompassing cavity enhanced methods) obtained in different kinds of plasma used in both research and industry. Full article
(This article belongs to the Special Issue Laser Spectroscopy and Sensing)
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Open AccessArticle Study on a Two-Dimensional Scanning Micro-Mirror and Its Application in a MOEMS Target Detector
Sensors 2010, 10(7), 6848-6860; https://doi.org/10.3390/s100706848
Received: 23 June 2010 / Revised: 16 July 2010 / Accepted: 16 July 2010 / Published: 16 July 2010
Cited by 9 | PDF Full-text (373 KB) | HTML Full-text | XML Full-text
Abstract
A two-dimensional (2D) scanning micro-mirror for target detection and measurement has been developed. This new micro-mirror is used in a MOEMS target detector to replace the conventional scanning detector. The micro-mirror is fabricated by MEMS process and actuated by a piezoelectric actuator. To
[...] Read more.
A two-dimensional (2D) scanning micro-mirror for target detection and measurement has been developed. This new micro-mirror is used in a MOEMS target detector to replace the conventional scanning detector. The micro-mirror is fabricated by MEMS process and actuated by a piezoelectric actuator. To achieve large deflection angles, the micro-mirror is excited in the resonance modes. It has two degrees of freedom and changes the direction of the emitted laser beam for a regional 2D scanning. For the deflection angles measurement, piezoresistors are integrated in the micro-mirror and the deflection angles of each direction can be detected independently and precisely. Based on the scanning micro-mirror and the phase-shift ranging technology, a MOEMS target detector has been developed in a size of 90 mm × 35 mm × 50 mm. The experiment shows that the target can be detected in the scanning field and the relative range and orientation can be measured by the MOEMS target detector. For the target distance up to 3 m with a field of view about 20º × 20º, the measurement resolution is about 10.2 cm in range, 0.15º in the horizontal direction and 0.22º in the vertical direction for orientation. Full article
(This article belongs to the Special Issue Intelligent Sensors - 2010)
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Open AccessArticle Optimization of Anodized-Aluminum Pressure-Sensitive Paint by Controlling Luminophore Concentration
Sensors 2010, 10(7), 6836-6847; https://doi.org/10.3390/s100706836
Received: 16 June 2010 / Revised: 8 July 2010 / Accepted: 13 July 2010 / Published: 16 July 2010
Cited by 11 | PDF Full-text (328 KB) | HTML Full-text | XML Full-text
Abstract
Anodized-aluminum pressure-sensitive paint (AA-PSP) has been used as a global pressure sensor for unsteady flow measurements. We use a dipping deposition method to apply a luminophore on a porous anodized-aluminum surface, controlling the luminophore concentration of the dipping method to optimize AA-PSP characteristics.
[...] Read more.
Anodized-aluminum pressure-sensitive paint (AA-PSP) has been used as a global pressure sensor for unsteady flow measurements. We use a dipping deposition method to apply a luminophore on a porous anodized-aluminum surface, controlling the luminophore concentration of the dipping method to optimize AA-PSP characteristics. The concentration is varied from 0.001 to 10 mM. Characterizations include the pressure sensitivity, the temperature dependency, and the signal level. The pressure sensitivity shows around 60 % at a lower concentration up to 0.1 mM. Above this concentration, the sensitivity reduces to a half. The temperature dependency becomes more than a half by setting the luminophore concentration from 0.001 to 10 mM. There is 3.6-fold change in the signal level by varying the concentration. To discuss an optimum concentration, a weight coefficient is introduced. We can arbitrarily change the coefficients to create an optimized AA-PSP for our sensing purposes. Full article
(This article belongs to the Section Chemical Sensors)
Open AccessArticle Voltammetry under a Controlled Temperature Gradient
Sensors 2010, 10(7), 6821-6835; https://doi.org/10.3390/s100706821
Received: 30 May 2010 / Revised: 20 June 2010 / Accepted: 1 July 2010 / Published: 14 July 2010
Cited by 4 | PDF Full-text (572 KB) | HTML Full-text | XML Full-text
Abstract
Electrochemical measurements are generally done under isothermal conditions. Here we report on the application of a controlled temperature gradient between the working electrode surface and the solution. Using electrochemical sensors prepared on ceramic materials with extremely high specific heat conductivity, the temperature gradient
[...] Read more.
Electrochemical measurements are generally done under isothermal conditions. Here we report on the application of a controlled temperature gradient between the working electrode surface and the solution. Using electrochemical sensors prepared on ceramic materials with extremely high specific heat conductivity, the temperature gradient between the electrode and solution was applied here as a second driving force. This application of the Soret phenomenon increases the mass transfer in the Nernst layer and enables more accurate control of the electrode response enhancement by a combination of diffusion and thermal diffusion. We have thus studied the effect of Soret phenomenon by cyclic voltammetry measurements in ferro/ferricyanide. The time dependence of sensor response disappears when applying the Soret phenomenon, and the complicated shape of the cyclic voltammogram is replaced by a simple exponential curve. We have derived the Cotrell-Soret equation describing the steady-state response with an applied temperature difference. Full article
(This article belongs to the Section Chemical Sensors)
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Open AccessReview Intelligent Chiral Sensing Based on Supramolecular and Interfacial Concepts
Sensors 2010, 10(7), 6796-6820; https://doi.org/10.3390/s100706796
Received: 17 June 2010 / Revised: 7 July 2010 / Accepted: 8 July 2010 / Published: 13 July 2010
Cited by 39 | PDF Full-text (421 KB) | HTML Full-text | XML Full-text
Abstract
Of the known intelligently-operating systems, the majority can undoubtedly be classed as being of biological origin. One of the notable differences between biological and artificial systems is the important fact that biological materials consist mostly of chiral molecules. While most biochemical processes routinely
[...] Read more.
Of the known intelligently-operating systems, the majority can undoubtedly be classed as being of biological origin. One of the notable differences between biological and artificial systems is the important fact that biological materials consist mostly of chiral molecules. While most biochemical processes routinely discriminate chiral molecules, differentiation between chiral molecules in artificial systems is currently one of the challenging subjects in the field of molecular recognition. Therefore, one of the important challenges for intelligent man-made sensors is to prepare a sensing system that can discriminate chiral molecules. Because intermolecular interactions and detection at surfaces are respectively parts of supramolecular chemistry and interfacial science, chiral sensing based on supramolecular and interfacial concepts is a significant topic. In this review, we briefly summarize recent advances in these fields, including supramolecular hosts for color detection on chiral sensing, indicator-displacement assays, kinetic resolution in supramolecular reactions with analyses by mass spectrometry, use of chiral shape-defined polymers, such as dynamic helical polymers, molecular imprinting, thin films on surfaces of devices such as QCM, functional electrodes, FET, and SPR, the combined technique of magnetic resonance imaging and immunoassay, and chiral detection using scanning tunneling microscopy and cantilever technology. In addition, we will discuss novel concepts in recent research including the use of achiral reagents for chiral sensing with NMR, and mechanical control of chiral sensing. The importance of integration of chiral sensing systems with rapidly developing nanotechnology and nanomaterials is also emphasized. Full article
(This article belongs to the Special Issue Intelligent Sensors - 2010)
Open AccessArticle A Microring Resonator Sensor for Sensitive Detection of 1,3,5-Trinitrotoluene (TNT)
Sensors 2010, 10(7), 6788-6795; https://doi.org/10.3390/s100706788
Received: 6 April 2010 / Revised: 8 June 2010 / Accepted: 24 June 2010 / Published: 13 July 2010
Cited by 59 | PDF Full-text (378 KB) | HTML Full-text | XML Full-text
Abstract
A microring resonator sensor device for sensitive detection of the explosive 1,3,5-trinitrotoluene (TNT) is presented. It is based on the combination of a silicon microring resonator and tailored receptor molecules. Full article
(This article belongs to the Special Issue Laser Spectroscopy and Sensing)
Open AccessReview Catalysts as Sensors—A Promising Novel Approach in Automotive Exhaust Gas Aftertreatment
Sensors 2010, 10(7), 6773-6787; https://doi.org/10.3390/s100706773
Received: 4 June 2010 / Revised: 7 July 2010 / Accepted: 9 July 2010 / Published: 13 July 2010
Cited by 49 | PDF Full-text (1292 KB) | HTML Full-text | XML Full-text
Abstract
Sensors that detect directly and in situ the status of automotive exhaust gas catalysts by monitoring the electrical properties of the catalyst coating itself are overviewed. Examples included in this review are the in-situ determination of the electrical impedance of three-way catalysts based
[...] Read more.
Sensors that detect directly and in situ the status of automotive exhaust gas catalysts by monitoring the electrical properties of the catalyst coating itself are overviewed. Examples included in this review are the in-situ determination of the electrical impedance of three-way catalysts based on ceria-zirconia solutions and of lean NOx traps of earth-alkaline based coatings, as well as approaches to determine the ammonia loading in Fe-SCR-zeolites with electrical ac measurements. Even more sophisticated approaches based on interactions with electromagnetic waves are also reviewed. For that purpose, metallic stick-like antennas are inserted into the exhaust pipe. The catalyst properties are measured in a contactless manner, directly indicating the catalyst status. The radio frequency probes gauge the oxygen loading degree of three-way catalysts, the NOx-loading of lean NOx traps, and the soot loading of Diesel particulate filters Full article
(This article belongs to the Section Chemical Sensors)
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