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Sensors, Volume 8, Issue 10 (October 2008), Pages 6125-6790

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Open AccessArticle Interfacial Recognition of Acetylcholine by an Amphiphilic p-Sulfonatocalix[8]arene Derivative Incorporated into Dimyristoyl Phosphatidylcholine Vesicles
Sensors 2008, 8(10), 6777-6790; https://doi.org/10.3390/s8106777
Received: 23 August 2008 / Revised: 17 October 2008 / Accepted: 23 October 2008 / Published: 29 October 2008
Cited by 13 | PDF Full-text (580 KB) | HTML Full-text | XML Full-text
Abstract
Dodecyl ether derivatives 1-3 of p-sulfonatocalix[n]arene were incorporated into dimyristoyl phosphatidylcholine (DMPC) vesicles, and their binding abilities for acetylcholine (ACh) were examined by using steady-state fluorescence/fluorescence anisotropy and fluorescence correlation spectroscopy (FCS). For the detection of ACh binding to the DMPC vesicles containing
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Dodecyl ether derivatives 1-3 of p-sulfonatocalix[n]arene were incorporated into dimyristoyl phosphatidylcholine (DMPC) vesicles, and their binding abilities for acetylcholine (ACh) were examined by using steady-state fluorescence/fluorescence anisotropy and fluorescence correlation spectroscopy (FCS). For the detection of ACh binding to the DMPC vesicles containing 5 mol % of 1-3, competitive fluorophore displacement experiments were performed, where rhodamine 6G (Rh6G) was used as a fluorescent guest. The addition of Rh6G to the DMPC vesicles containing 3 resulted in a decrease in the fluorescence intensity of Rh6G with an increase of its fluorescence anisotropy, indicating that Rh6G binds to the DMPC-3 vesicles. In the case of DMPC-1 and DMPC-2 vesicles, significant changes in the fluorescence spectra of Rh6G were not observed. When ACh was added to the DMPC-3 vesicles in the presence of Rh6G ([3]/[Rh6G]=100), the fluorescence intensity of Rh6G increased with a decrease in its fluorescence anisotropy. From the analysis of fluorescence titration data, the association constants were determined to be 7.1×105 M-1 for Rh6G-3 complex and 1.1×102 M-1 for ACh-3 complex at the DMPC-3 vesicles. To get a direct evidence for the binding of Rh6G and its displacement by ACh at the DMPC-3 vesicles, diffusion times of the Rh6G were measured by using FCS. Binding selectivity of the DMPC-3 vesicles for ACh, choline, GABA, L-aspartic acid, L-glutamic acid, L-arginine, L-lysine, L-histamine and ammonium chloride was also evaluated using FCS. Full article
(This article belongs to the Special Issue Molecular Recognition and Sensors, Including Molecular Imprinting)
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Open AccessArticle Linear FBG Temperature Sensor Interrogation with Fabry-Perot ITU Multi-wavelength Reference
Sensors 2008, 8(10), 6769-6776; https://doi.org/10.3390/s8106769
Received: 9 October 2008 / Revised: 20 October 2008 / Accepted: 28 October 2008 / Published: 29 October 2008
Cited by 27 | PDF Full-text (350 KB) | HTML Full-text | XML Full-text
Abstract
The equidistantly spaced multi-passbands of a Fabry-Perot ITU filter are used as an efficient multi-wavelength reference for fiber Bragg grating sensor demodulation. To compensate for the nonlinear wavelength tuning effect in the FBG sensor demodulator, a polynomial fitting algorithm was applied to the
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The equidistantly spaced multi-passbands of a Fabry-Perot ITU filter are used as an efficient multi-wavelength reference for fiber Bragg grating sensor demodulation. To compensate for the nonlinear wavelength tuning effect in the FBG sensor demodulator, a polynomial fitting algorithm was applied to the temporal peaks of the wavelength-scanned ITU filter. The fitted wavelength values are assigned to the peak locations of the FBG sensor reflections, obtaining constant accuracy, regardless of the wavelength scan range and frequency. A linearity error of about 0.18% against a reference thermocouple thermometer was obtained with the suggested method. Full article
(This article belongs to the Section Chemical Sensors)
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Open AccessArticle Modeling of an Optical Sensor Based on Whispering Gallery Modes (WGMs) on the Surface Guiding Layer of Glass Filaments
Sensors 2008, 8(10), 6761-6768; https://doi.org/10.3390/s8106761
Received: 22 September 2008 / Revised: 10 October 2008 / Accepted: 24 October 2008 / Published: 28 October 2008
Cited by 11 | PDF Full-text (251 KB) | HTML Full-text | XML Full-text
Abstract
A ring-resonator-based refractive index sensor is proposed in this paper. Glass filaments with surface guiding layers created by ion exchange are crossed with a fiber taper to act as a ring resonator sensor. Theoretical simulation of the sensor response is proposed, and optimization
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A ring-resonator-based refractive index sensor is proposed in this paper. Glass filaments with surface guiding layers created by ion exchange are crossed with a fiber taper to act as a ring resonator sensor. Theoretical simulation of the sensor response is proposed, and optimization of structural parameters including thickness and refractive index of the surface guiding layer and the diameter of the ring resonator for higher sensitivity is investigated. Results show that a detection limit of a variation of ~10-5RIU can be reached. Due to its simple fabrication and easy manipulation as well as good sensing performance, we believe such a micro-cavity sensor will find potential applications in high sensitivity optical sensing. Full article
(This article belongs to the Section Chemical Sensors)
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Open AccessArticle Optimization of Single-Sensor Two-State Hot-Wire Anemometer Transmission Bandwidth
Sensors 2008, 8(10), 6747-6760; https://doi.org/10.3390/s8106747
Received: 1 September 2008 / Revised: 10 October 2008 / Accepted: 24 October 2008 / Published: 28 October 2008
Cited by 7 | PDF Full-text (315 KB) | HTML Full-text | XML Full-text
Abstract
Hot-wire anemometric measurements of non-isothermal flows require the use of thermal compensation or correction circuitry. One possible solution is a two-state hot-wire anemometer that uses the cyclically changing heating level of a single sensor. The area in which flow velocity and fluid temperature
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Hot-wire anemometric measurements of non-isothermal flows require the use of thermal compensation or correction circuitry. One possible solution is a two-state hot-wire anemometer that uses the cyclically changing heating level of a single sensor. The area in which flow velocity and fluid temperature can be measured is limited by the dimensions of the sensor’s active element. The system is designed to measure flows characterized by high velocity and temperature gradients, although its transmission bandwidth is very limited. In this study, we propose a method to optimize the two-state hot-wire anemometer transmission bandwidth. The method is based on the use of a specialized constanttemperature system together with variable dynamic parameters. It is also based on a suitable measurement cycle paradigm. Analysis of the method was undertaken using model testing. Our results reveal a possible significant broadening of the two-state hot-wire anemometer's transmission bandwidth. Full article
(This article belongs to the Special Issue Sensor Algorithms)
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Open AccessArticle Immunoglobulin G Determination in Human Serum and Milk Using an Immunosensor of New Conception Fitted with an Enzyme Probe as Transducer
Sensors 2008, 8(10), 6727-6746; https://doi.org/10.3390/s8106727
Received: 20 May 2008 / Revised: 6 September 2008 / Accepted: 17 October 2008 / Published: 28 October 2008
Cited by 8 | PDF Full-text (219 KB) | HTML Full-text | XML Full-text
Abstract
To completely overcome the problem of the presence of urea in the serum, which can be the cause (especially at low immunoglobulin G concentrations) of a small but non negligible interference in the enzyme reaction of the enzymatic marker, when the measurement was
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To completely overcome the problem of the presence of urea in the serum, which can be the cause (especially at low immunoglobulin G concentrations) of a small but non negligible interference in the enzyme reaction of the enzymatic marker, when the measurement was performed by a potentiometric immunosensor that we constructed and characterized in previous work, and which used urease as marker, we have now constructed an entirely different and highly innovative immunosensor. This new device uses the enzyme alkaline phosphatase as marker, sodium phenylphosphate as substrate but above all, a tyrosinase biosensor obtained by coupling a Clark type gas diffusion amperometric electrode and the tyrosinase enzyme, immobilized in a cellulose triacetate membrane, as transducer. After optimizing the ‘competitive’ measurement procedures, the new immunosensor was used to determine both HIgG and the anti-HIgG, with a limit of detection (LOD) of the order of 3x10-11 M. Clearly this highly innovative construction geometry makes the immunosensor extremely selective. This makes it possible to determine immunoglobulin G both in human serum and milk without the slightest interference by any urea present in these biological matrixes. Full article
(This article belongs to the Section Biosensors)
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Open AccessReview NeuroMEMS: Neural Probe Microtechnologies
Sensors 2008, 8(10), 6704-6726; https://doi.org/10.3390/s8106704
Received: 2 July 2008 / Revised: 27 September 2008 / Accepted: 21 October 2008 / Published: 25 October 2008
Cited by 110 | PDF Full-text (2316 KB) | HTML Full-text | XML Full-text
Abstract
Neural probe technologies have already had a significant positive effect on our understanding of the brain by revealing the functioning of networks of biological neurons. Probes are implanted in different areas of the brain to record and/or stimulate specific sites in the brain.
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Neural probe technologies have already had a significant positive effect on our understanding of the brain by revealing the functioning of networks of biological neurons. Probes are implanted in different areas of the brain to record and/or stimulate specific sites in the brain. Neural probes are currently used in many clinical settings for diagnosis of brain diseases such as seizers, epilepsy, migraine, Alzheimer’s, and dementia. We find these devices assisting paralyzed patients by allowing them to operate computers or robots using their neural activity. In recent years, probe technologies were assisted by rapid advancements in microfabrication and microelectronic technologies and thus are enabling highly functional and robust neural probes which are opening new and exciting avenues in neural sciences and brain machine interfaces. With a wide variety of probes that have been designed, fabricated, and tested to date, this review aims to provide an overview of the advances and recent progress in the microfabrication techniques of neural probes. In addition, we aim to highlight the challenges faced in developing and implementing ultralong multi-site recording probes that are needed to monitor neural activity from deeper regions in the brain. Finally, we review techniques that can improve the biocompatibility of the neural probes to minimize the immune response and encourage neural growth around the electrodes for long term implantation studies. Full article
(This article belongs to the Special Issue BioMEMS)
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Open AccessArticle Comparative and Combinative Study of Urban Heat island in Wuhan City with Remote Sensing and CFD Simulation
Sensors 2008, 8(10), 6692-6703; https://doi.org/10.3390/s8106692
Received: 26 March 2008 / Revised: 28 September 2008 / Accepted: 21 October 2008 / Published: 25 October 2008
Cited by 15 | PDF Full-text (541 KB) | HTML Full-text | XML Full-text
Abstract
Urban heat islands are one of the most critical urban environment heat problems. Landsat ETM+ satellite data were used to investigate the land surface temperature and underlying surface indices such as NDVI and NDBI. A comparative study of the urban heat environment at
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Urban heat islands are one of the most critical urban environment heat problems. Landsat ETM+ satellite data were used to investigate the land surface temperature and underlying surface indices such as NDVI and NDBI. A comparative study of the urban heat environment at different scales, times and locations was done to verify the heat island characteristics. Since remote sensing technology has limitations for dynamic flow analysis in the study of urban spaces, a CFD simulation was used to validate the improvement of the heat environment in a city by means of wind. CFD technology has its own shortcomings in parameter setting and verification, while RS technology is helpful to remedy this. The city of Wuhan and its climatological condition of being hot in summer and cold in winter were chosen to verify the comparative and combinative application of RS with CFD in studying the urban heat island. Full article
(This article belongs to the Special Issue Sensors for Urban Environmental Monitoring)
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Open AccessArticle Impact of Link Unreliability and Asymmetry on the Quality of Connectivity in Large-scale Sensor Networks
Sensors 2008, 8(10), 6674-6691; https://doi.org/10.3390/s8106674
Received: 1 July 2008 / Revised: 12 October 2008 / Accepted: 22 October 2008 / Published: 24 October 2008
Cited by 6 | PDF Full-text (300 KB) | HTML Full-text | XML Full-text
Abstract
Connectivity is a fundamental issue in research on wireless sensor networks. However, unreliable and asymmetric links have a great impact on the global quality of connectivity (QoC). By assuming the deployment of nodes a homogeneous Poisson point process and eliminating the border effect,
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Connectivity is a fundamental issue in research on wireless sensor networks. However, unreliable and asymmetric links have a great impact on the global quality of connectivity (QoC). By assuming the deployment of nodes a homogeneous Poisson point process and eliminating the border effect, this paper derives an explicit expression of node non-isolation probability as the upper bound of one-connectivity, based on an analytical link model which incorporates important parameters such as path loss exponent, shadowing variance of channel, modulation, encoding method etc. The derivation has built a bridge over the local link property and the global network connectivity, which makes it clear to see how various parameter impact the QoC. Numerical results obtained further confirm the analysis and can be used as reference for practical design and simulation of wireless ad hoc and sensor networks. Besides, we find giant component size a good relaxed measure of connectivity in some applications that do not require full connectivity. Full article
(This article belongs to the Section Chemical Sensors)
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Open AccessArticle Surface-Modified Gold Nanoparticles with Folic Acid as Optical Probes for Cellular Imaging
Sensors 2008, 8(10), 6660-6673; https://doi.org/10.3390/s8106660
Received: 24 July 2008 / Revised: 21 September 2008 / Accepted: 21 October 2008 / Published: 24 October 2008
Cited by 33 | PDF Full-text (1143 KB) | HTML Full-text | XML Full-text
Abstract
In this study, we demonstrate that the uptake rate of the surface-modified gold nanoparticles (GNPs) with folic acid by specific cells can be increased significantly, if the membranes of these cells have sufficient folic-acid receptors. Two human breast cancer cell lines were studied;
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In this study, we demonstrate that the uptake rate of the surface-modified gold nanoparticles (GNPs) with folic acid by specific cells can be increased significantly, if the membranes of these cells have sufficient folic-acid receptors. Two human breast cancer cell lines were studied; one is MDA-MB-435S cell, and the other T-47D cell. The expression of the folic acid receptors of the former is much higher than that of the latter. These cells were incubated with media containing bare GNPs or GNPs conjugated with folic acid individually. Due to the unique optical behavior (i.e. surface plasmon resonance) of GNPs, the uptake amount of GNPs by cells can be identified by using the laser scanning confocal microscopy. Our experiments show that the uptake amount of GNPs in MDAMB-435S cells is higher than that in T-47D cells for the same culture time, if the culture medium contains bare GNPs. Moreover, if the GNPs conjugated with folic acid are used for the culture, the uptake rate of GNPs by MDA-MB-435S cells is improved more. In contrast, the uptake rates of both GNPs are almost the same by T-47D cells. The phenomenon indicates that the uptake rate of GNPs can be improved via the ligand-receptor endocytosis, compared with the nonspecific endocytosis. Therefore, the uptake rate of GNPs conjugated with folic acid by MDA-MB-435S cells is higher than that of bare GNPs. Full article
(This article belongs to the Section Biosensors)
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Open AccessReview Oil Spill Detection by SAR Images: Dark Formation Detection, Feature Extraction and Classification Algorithms
Sensors 2008, 8(10), 6642-6659; https://doi.org/10.3390/s8106642
Received: 10 June 2008 / Revised: 24 August 2008 / Accepted: 21 October 2008 / Published: 23 October 2008
Cited by 125 | PDF Full-text (278 KB) | HTML Full-text | XML Full-text
Abstract
This paper provides a comprehensive review of the use of Synthetic Aperture Radar images (SAR) for detection of illegal discharges from ships. It summarizes the current state of the art, covering operational and research aspects of the application. Oil spills are seriously affecting
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This paper provides a comprehensive review of the use of Synthetic Aperture Radar images (SAR) for detection of illegal discharges from ships. It summarizes the current state of the art, covering operational and research aspects of the application. Oil spills are seriously affecting the marine ecosystem and cause political and scientific concern since they seriously effect fragile marine and coastal ecosystem. The amount of pollutant discharges and associated effects on the marine environment are important parameters in evaluating sea water quality. Satellite images can improve the possibilities for the detection of oil spills as they cover large areas and offer an economical and easier way of continuous coast areas patrolling. SAR images have been widely used for oil spill detection. The present paper gives an overview of the methodologies used to detect oil spills on the radar images. In particular we concentrate on the use of the manual and automatic approaches to distinguish oil spills from other natural phenomena. We discuss the most common techniques to detect dark formations on the SAR images, the features which are extracted from the detected dark formations and the most used classifiers. Finally we conclude with discussion of suggestions for further research. The references throughout the review can serve as starting point for more intensive studies on the subject. Full article
(This article belongs to the Special Issue Synthetic Aperture Radar (SAR))
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Open AccessReview Molecular Recognition and Specific Interactions for Biosensing Applications
Sensors 2008, 8(10), 6605-6641; https://doi.org/10.3390/s8106605
Received: 25 September 2008 / Revised: 16 October 2008 / Accepted: 20 October 2008 / Published: 23 October 2008
Cited by 40 | PDF Full-text (1361 KB) | HTML Full-text | XML Full-text
Abstract
Molecular recognition and specific interactions are reliable and versatile routes for site-specific and well-oriented immobilization of functional biomolecules on surfaces. The control of surface properties via the molecular recognition and specific interactions at the nanoscale is a key element for the nanofabrication of
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Molecular recognition and specific interactions are reliable and versatile routes for site-specific and well-oriented immobilization of functional biomolecules on surfaces. The control of surface properties via the molecular recognition and specific interactions at the nanoscale is a key element for the nanofabrication of biosensors with high sensitivity and specificity. This review intends to provide a comprehensive understanding of the molecular recognition- and specific interaction-mediated biosensor fabrication routes that leads to biosensors with well-ordered and controlled structures on both nanopatterned surfaces and nanomaterials. Herein self-assembly of the biomolecules via the molecular recognition and specific interactions on nanoscaled surfaces as well as nanofabrication techniques of the biomolecules for biosensor architecture are discussed. We also describe the detection of molecular recognition- and specific interaction-mediated molecular binding as well as advantages of nanoscale detection. Full article
(This article belongs to the Special Issue Molecular Recognition and Sensors, Including Molecular Imprinting)
Open AccessArticle Femtosecond Laser Microfabrication of an Integrated Device for Optical Release and Sensing of Bioactive Compounds
Sensors 2008, 8(10), 6595-6604; https://doi.org/10.3390/s8106595
Received: 23 September 2008 / Revised: 16 October 2008 / Accepted: 21 October 2008 / Published: 23 October 2008
Cited by 5 | PDF Full-text (1902 KB) | HTML Full-text | XML Full-text
Abstract
Flash photolysis of caged compounds is one of the most powerful approaches to investigate the dynamic response of living cells. Monolithically integrated devices suitable for optical uncaging are in great demand since they greatly simplify the experiments and allow their automation. Here we
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Flash photolysis of caged compounds is one of the most powerful approaches to investigate the dynamic response of living cells. Monolithically integrated devices suitable for optical uncaging are in great demand since they greatly simplify the experiments and allow their automation. Here we demonstrate the fabrication of an integrated bio-photonic device for the optical release of caged compounds. Such a device is fabricated using femtosecond laser micromachining of a glass substrate. More in detail, femtosecond lasers are used both to cut the substrate in order to create a pit for cell growth and to inscribe optical waveguides for spatially selective uncaging of the compounds present in the culture medium. The operation of this monolithic bio-photonic device is tested using both free and caged fluorescent compounds to probe its capability of multipoint release and optical sensing. Application of this device to the study of neuronal network activity can be envisaged. Full article
(This article belongs to the Special Issue State-of-the-Art Sensors Technology in Italy)
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Open AccessReview A Review of the CMOS Buried Double Junction (BDJ) Photodetector and its Applications
Sensors 2008, 8(10), 6566-6594; https://doi.org/10.3390/s8106566
Received: 8 July 2008 / Revised: 4 September 2008 / Accepted: 17 October 2008 / Published: 23 October 2008
Cited by 15 | PDF Full-text (1559 KB) | HTML Full-text | XML Full-text
Abstract
A CMOS Buried Double Junction PN (BDJ) photodetector consists of two vertically-stacked photodiodes. It can be operated as a photodiode with improved performance and wavelength-sensitive response. This paper presents a review of this device and its applications. The CMOS implementation and operating principle
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A CMOS Buried Double Junction PN (BDJ) photodetector consists of two vertically-stacked photodiodes. It can be operated as a photodiode with improved performance and wavelength-sensitive response. This paper presents a review of this device and its applications. The CMOS implementation and operating principle are firstly described. This includes the description of several key aspects directly related to the device performances, such as surface reflection, photon absorption and electron-hole pair generation, photocurrent and dark current generation, etc. SPICE modelling of the detector is then presented. Next, design and process considerations are proposed in order to improve the BDJ performance. Finally, several BDJ-detector-based image sensors provide a survey of their applications. Full article
(This article belongs to the Special Issue Integrated High-performance Imagers)
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Open AccessArticle Pre-Launch Absolute Calibration of CCD/CBERS-2B Sensor
Sensors 2008, 8(10), 6557-6565; https://doi.org/10.3390/s8106557
Received: 26 August 2008 / Revised: 25 September 2008 / Accepted: 21 October 2008 / Published: 23 October 2008
Cited by 4 | PDF Full-text (407 KB) | HTML Full-text | XML Full-text
Abstract
Pre-launch absolute calibration coefficients for the CCD/CBERS-2B sensor have been calculated from radiometric measurements performed in a satellite integration and test hall in the Chinese Academy of Space Technology (CAST) headquarters, located in Beijing, China. An illuminated integrating sphere was positioned in the
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Pre-launch absolute calibration coefficients for the CCD/CBERS-2B sensor have been calculated from radiometric measurements performed in a satellite integration and test hall in the Chinese Academy of Space Technology (CAST) headquarters, located in Beijing, China. An illuminated integrating sphere was positioned in the test hall facilities to allow the CCD/CBERS-2B imagery of the entire sphere aperture. Calibration images were recorded and a relative calibration procedure adopted exclusively in Brazil was applied to equalize the detectors responses. Averages of digital numbers (DN) from these images were determined and correlated to their respective radiance levels in order to calculate the absolute calibration coefficients. It has been the first time these pre-launch absolute calibration coefficients have been calculated considering the Brazilian image processing criteria. Now it will be possible to compare them to those that will be calculated from vicarious calibration campaigns. This comparison will permit the CCD/CBERS-2B monitoring and the frequently data updating to the user community. Full article
(This article belongs to the Section Remote Sensors)
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Open AccessArticle Porous Silicon Based Resonant Mirrors for Biochemical Sensing
Sensors 2008, 8(10), 6549-6556; https://doi.org/10.3390/s8106549
Received: 6 June 2008 / Revised: 6 October 2008 / Accepted: 21 October 2008 / Published: 23 October 2008
Cited by 31 | PDF Full-text (282 KB) | HTML Full-text | XML Full-text
Abstract
We report on our preliminary results in the realization and characterization of a porous silicon (PSi) resonant mirror (RM) for optical biosensing. We have numerically and experimentally studied the coupling between the electromagnetic field, totally reflected at the base of a high refractive
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We report on our preliminary results in the realization and characterization of a porous silicon (PSi) resonant mirror (RM) for optical biosensing. We have numerically and experimentally studied the coupling between the electromagnetic field, totally reflected at the base of a high refractive index prism, and the optical modes of a PSi waveguide. This configuration is very sensitive to changes in the refractive index and/or in thickness of the sensor surface. Due to the high specific area of the PSi waveguide, very low DNA concentrations can be detected confirming that the RM could be a very sensitive and labelfree optical biosensor. Full article
(This article belongs to the Section Biosensors)
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