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Sensors, Volume 10, Issue 4 (April 2010), Pages 2460-4179

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Open AccessArticle Non-Linearity Analysis of Depth and Angular Indexes for Optimal Stereo SLAM
Sensors 2010, 10(4), 4159-4179; https://doi.org/10.3390/s100404159
Received: 22 March 2010 / Revised: 19 April 2010 / Accepted: 20 April 2010 / Published: 26 April 2010
Cited by 4 | PDF Full-text (607 KB) | HTML Full-text | XML Full-text | Supplementary Files
Abstract
In this article, we present a real-time 6DoF egomotion estimation system for indoor environments using a wide-angle stereo camera as the only sensor. The stereo camera is carried in hand by a person walking at normal walking speeds 3–5 km/h. We present the
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In this article, we present a real-time 6DoF egomotion estimation system for indoor environments using a wide-angle stereo camera as the only sensor. The stereo camera is carried in hand by a person walking at normal walking speeds 3–5 km/h. We present the basis for a vision-based system that would assist the navigation of the visually impaired by either providing information about their current position and orientation or guiding them to their destination through different sensing modalities. Our sensor combines two different types of feature parametrization: inverse depth and 3D in order to provide orientation and depth information at the same time. Natural landmarks are extracted from the image and are stored as 3D or inverse depth points, depending on a depth threshold. This depth threshold is used for switching between both parametrizations and it is computed by means of a non-linearity analysis of the stereo sensor. Main steps of our system approach are presented as well as an analysis about the optimal way to calculate the depth threshold. At the moment each landmark is initialized, the normal of the patch surface is computed using the information of the stereo pair. In order to improve long-term tracking, a patch warping is done considering the normal vector information. Some experimental results under indoor environments and conclusions are presented. Full article
(This article belongs to the Special Issue Motion Detectors)
Open AccessArticle Corrosion Sensor for Monitoring the Service Condition of Chloride-Contaminated Cement Mortar
Sensors 2010, 10(4), 4145-4158; https://doi.org/10.3390/s100404145
Received: 4 March 2010 / Revised: 13 April 2010 / Accepted: 19 April 2010 / Published: 26 April 2010
Cited by 10 | PDF Full-text (326 KB) | HTML Full-text | XML Full-text
Abstract
A corrosion sensor for monitoring the corrosion state of cover mortar was developed. The sensor was tested in cement mortar, with and without the addition of chloride to simulate the adverse effects of chloride-contaminated environmental conditions on concrete structures. In brief, a linear
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A corrosion sensor for monitoring the corrosion state of cover mortar was developed. The sensor was tested in cement mortar, with and without the addition of chloride to simulate the adverse effects of chloride-contaminated environmental conditions on concrete structures. In brief, a linear polarization resistance method combined with an embeddable reference electrode was utilized to measure the polarization resistance (Rp) using built-in sensor electrodes. Subsequently, electrochemical impedance spectroscopy in the frequency range of 1 kHz to 50 kHz was used to obtain the cement mortar resistance (Rs). The results show that the polarization resistance is related to the chloride content and Rs; ln (Rp) is linearly related to the Rs values in mortar without added chloride. The relationships observed between the Rp of the steel anodes and the resistance of the surrounding cement mortar measured by the corrosion sensor confirms that Rs can indicate the corrosion state of concrete structures. Full article
(This article belongs to the Section Chemical Sensors)
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Open AccessArticle Design and Simulation of a MEMS Control Moment Gyroscope for the Sub-Kilogram Spacecraft
Sensors 2010, 10(4), 4130-4144; https://doi.org/10.3390/s100404130
Received: 8 March 2010 / Revised: 19 April 2010 / Accepted: 20 April 2010 / Published: 26 April 2010
Cited by 6 | PDF Full-text (465 KB) | HTML Full-text | XML Full-text
Abstract
A novel design of a microelectromechanical systems (MEMS) control moment gyroscope (MCMG) was proposed in this paper in order to generate a torque output with a magnitude of 10-6 N∙m. The MCMG consists of two orthogonal angular vibration systems, i.e., the rotor
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A novel design of a microelectromechanical systems (MEMS) control moment gyroscope (MCMG) was proposed in this paper in order to generate a torque output with a magnitude of 10-6 N∙m. The MCMG consists of two orthogonal angular vibration systems, i.e., the rotor and gimbal; the coupling between which is based on the Coriolis effect and will cause a torque output in the direction perpendicular to the two vibrations. The angular rotor vibration was excited by the in-plane electrostatic rotary comb actuators, while the angular gimbal vibration was driven by an out-of-plane electrostatic parallel plate actuator. A possible process flow to fabricate the structure was proposed and discussed step by step. Furthermore, an array configuration using four MCMGs as an effective element, in which the torque was generated with a phase difference of 90 degrees between every two MCMGs, was proposed to smooth the inherent fluctuation of the torque output for a vibrational MCMG. The parasitic torque was cancelled by two opposite MCMGs with a phase difference of 180 degrees. The designed MCMG was about 1.1 cm × 1.1 cm × 0.04 cm in size and 0.1 g in weight. The simulation results showed that the maximum torque output of a MCMG, the resonant frequency of which was approximately 1,000 Hz, was about 2.5 × 10-8 N∙m. The element with four MCMGs could generate a torque of 5 × 10-8 N∙m. The torque output could reach a magnitude of 10-6 N∙m when the frequency was improved from 1,000 Hz to 10,000 Hz. Using arrays of 4 × 4 effective elements on a 1 kg spacecraft with a standard form factor of 10 cm × 10 cm × 10 cm, a 10 degrees attitude change could be achieved in 26.96s. Full article
(This article belongs to the Section Chemical Sensors)
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Open AccessArticle FPGA-Based Fused Smart Sensor for Dynamic and Vibration Parameter Extraction in Industrial Robot Links
Sensors 2010, 10(4), 4114-4129; https://doi.org/10.3390/s100404114
Received: 2 March 2010 / Revised: 20 April 2010 / Accepted: 20 April 2010 / Published: 26 April 2010
Cited by 21 | PDF Full-text (3738 KB) | HTML Full-text | XML Full-text
Abstract
Intelligent robotics demands the integration of smart sensors that allow the controller to efficiently measure physical quantities. Industrial manipulator robots require a constant monitoring of several parameters such as motion dynamics, inclination, and vibration. This work presents a novel smart sensor to estimate
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Intelligent robotics demands the integration of smart sensors that allow the controller to efficiently measure physical quantities. Industrial manipulator robots require a constant monitoring of several parameters such as motion dynamics, inclination, and vibration. This work presents a novel smart sensor to estimate motion dynamics, inclination, and vibration parameters on industrial manipulator robot links based on two primary sensors: an encoder and a triaxial accelerometer. The proposed smart sensor implements a new methodology based on an oversampling technique, averaging decimation filters, FIR filters, finite differences and linear interpolation to estimate the interest parameters, which are computed online utilizing digital hardware signal processing based on field programmable gate arrays (FPGA). Full article
(This article belongs to the Special Issue Intelligent Sensors - 2010)
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Open AccessArticle Ultra-High-Speed Image Signal Accumulation Sensor
Sensors 2010, 10(4), 4100-4113; https://doi.org/10.3390/s100404100
Received: 24 March 2010 / Revised: 8 April 2010 / Accepted: 16 April 2010 / Published: 23 April 2010
Cited by 7 | PDF Full-text (1901 KB) | HTML Full-text | XML Full-text
Abstract
Averaging of accumulated data is a standard technique applied to processing data with low signal-to-noise ratios (SNR), such as image signals captured in ultra-high-speed imaging. The authors propose an architecture layout of an ultra-high-speed image sensor capable of on-chip signal accumulation. The very
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Averaging of accumulated data is a standard technique applied to processing data with low signal-to-noise ratios (SNR), such as image signals captured in ultra-high-speed imaging. The authors propose an architecture layout of an ultra-high-speed image sensor capable of on-chip signal accumulation. The very high frame rate is enabled by employing an image sensor structure with a multi-folded CCD in each pixel, which serves as an in situ image signal storage. The signal accumulation function is achieved by direct connection of the first and the last storage elements of the in situ storage CCD. It has been thought that the multi-folding is achievable only by driving electrodes with complicated and impractical layouts. Simple configurations of the driving electrodes to overcome the difficulty are presented for two-phase and four-phase transfer CCD systems. The in situ storage image sensor with the signal accumulation function is named Image Signal Accumulation Sensor (ISAS). Full article
(This article belongs to the Special Issue Delft Workshop 2008-2009—Sensors and Imagers: a VLSI Perspective)
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Open AccessReview One-Dimensional Oxide Nanostructures as Gas-Sensing Materials: Review and Issues
Sensors 2010, 10(4), 4083-4099; https://doi.org/10.3390/s100404083
Received: 3 March 2010 / Revised: 15 April 2010 / Accepted: 16 April 2010 / Published: 22 April 2010
Cited by 202 | PDF Full-text (4543 KB) | HTML Full-text | XML Full-text
Abstract
In this article, we review gas sensor application of one-dimensional (1D) metal-oxide nanostructures with major emphases on the types of device structure and issues for realizing practical sensors. One of the most important steps in fabricating 1D-nanostructure devices is manipulation and making electrical
[...] Read more.
In this article, we review gas sensor application of one-dimensional (1D) metal-oxide nanostructures with major emphases on the types of device structure and issues for realizing practical sensors. One of the most important steps in fabricating 1D-nanostructure devices is manipulation and making electrical contacts of the nanostructures. Gas sensors based on individual 1D nanostructure, which were usually fabricated using electron-beam lithography, have been a platform technology for fundamental research. Recently, gas sensors with practical applicability were proposed, which were fabricated with an array of 1D nanostructures using scalable micro-fabrication tools. In the second part of the paper, some critical issues are pointed out including long-term stability, gas selectivity, and room-temperature operation of 1D-nanostructure-based metal-oxide gas sensors. Full article
(This article belongs to the Special Issue Metal-Oxide Based Nanosensors)
Open AccessArticle Towards Fully Integrated Wireless Impedimetric Sensors
Sensors 2010, 10(4), 4071-4082; https://doi.org/10.3390/s100404071
Received: 21 February 2010 / Revised: 10 March 2010 / Accepted: 13 April 2010 / Published: 21 April 2010
Cited by 13 | PDF Full-text (555 KB) | HTML Full-text | XML Full-text
Abstract
We report on the design and characterization of the building blocks of a single-chip wireless chemical sensor fabricated with a commercial complementary metal-oxide-silicon (CMOS) technology, which includes two types of transducers for impedimetric measurements (4-electrode array and two interdigitated electrodes), instrumentation circuits, and
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We report on the design and characterization of the building blocks of a single-chip wireless chemical sensor fabricated with a commercial complementary metal-oxide-silicon (CMOS) technology, which includes two types of transducers for impedimetric measurements (4-electrode array and two interdigitated electrodes), instrumentation circuits, and a metal coil and circuits for inductive power and data transfer. The electrodes have been formed with a polycrystalline silicon layer of the technology by a simple post-process that does not require additional deposition or lithography steps, but just etching steps. A linear response to both conductivity and permittivity of solutions has been obtained. Wireless communication of the sensor chip with a readout unit has been demonstrated. The design of the chip was prepared for individual block characterization and not for full system characterization. The integration of chemical transducers within monolithic wireless platforms will lead to smaller, cheaper, and more reliable chemical microsensors, and will open up the door to numerous new applications where liquid mediums that are enclosed in sealed receptacles have to be measured. Full article
(This article belongs to the Section Chemical Sensors)
Open AccessArticle Fluorescence-Based Comparative Binding Studies of the Supramolecular Host Properties of PAMAM Dendrimers Using Anilinonaphthalene Sulfonates: Unusual Host-Dependent Fluorescence Titration Behavior
Sensors 2010, 10(4), 4053-4070; https://doi.org/10.3390/s100404053
Received: 4 March 2010 / Revised: 31 March 2010 / Accepted: 13 April 2010 / Published: 21 April 2010
Cited by 7 | PDF Full-text (362 KB) | HTML Full-text | XML Full-text
Abstract
This work describes the fluorescence enhancement of the anilinonaphthalene sulfonate probes 1,8-ANS, 2,6-ANS, and 2,6-TNS via complexation with PAMAM dendrimer hosts of Generation 4, 5 and 6. The use of this set of three very closely related probes allows for comparative binding studies,
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This work describes the fluorescence enhancement of the anilinonaphthalene sulfonate probes 1,8-ANS, 2,6-ANS, and 2,6-TNS via complexation with PAMAM dendrimer hosts of Generation 4, 5 and 6. The use of this set of three very closely related probes allows for comparative binding studies, with specific pairs of probes differing only in shape (1,8-ANS and 2,6-ANS), or in the presence of a methyl substituent (2,6-TNS vs. 2,6-ANS). The fluorescence of all three probes was significantly enhanced upon binding with PAMAM dendrimers, however in all cases except one, a very unusual spike was consistently observed in the host fluorescence titration plots (fluorescence enhancement vs. host concentration) at low dendrimer concentration. This unprecedented fluorescence titration curve shape makes fitting the data to a simple model such as 1:1 or 2:1 host: guest complexation very difficult; thus only qualitative comparisons of the relative binding of the three guests could be made based on host titrations. In the case of G4 and G5 dendrimers, the order of binding strength was qualitatively determined to be 1,8-ANS < 2,6-ANS indicating that the more streamlined 2,6-substituted probes are a better match for the dendrimer cavity shape than the bulkier 1,8-substituted probe. This order of binding strength was also indicated by double fluorometric titration experiments, involving both host and guest titrations. Further double fluorometric titration experiments on 2,6-ANS in G4 dendrimer revealed a host concentration-dependent change in the nature of the host: guest complexation, with multiple guests complexed per host molecule at very low host concentrations, but less than one guest per host at higher concentrations. Full article
(This article belongs to the Special Issue Dendritic Sensors: From Dendrimer Molecules to Dendritic Cells)
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Open AccessArticle Design and Analysis of Impedance Pumps Utilizing Electromagnetic Actuation
Sensors 2010, 10(4), 4040-4052; https://doi.org/10.3390/s100404040
Received: 25 February 2010 / Revised: 19 March 2010 / Accepted: 9 April 2010 / Published: 21 April 2010
Cited by 18 | PDF Full-text (349 KB) | HTML Full-text | XML Full-text
Abstract
This study designs and analyzes an impedance pump utilizing an electromagnetic actuator. The pump is designed to have three major components, namely a lower glass substrate patterned with a copper micro-coil, a microchannel, and an upper glass cover plate attached a magnetic PDMS
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This study designs and analyzes an impedance pump utilizing an electromagnetic actuator. The pump is designed to have three major components, namely a lower glass substrate patterned with a copper micro-coil, a microchannel, and an upper glass cover plate attached a magnetic PDMS diaphragm. When a current is passed through the micro-coil, an electromagnetic force is established between the coil and the magnetic diaphragm. The resulting deflection of the PDMS diaphragm creates an acoustic impedance mismatch within the microchannel, which results in a net flow. In performing the analysis, simulated models of the magnetic field, the diaphragm displacement and the flow rate are developed using Ansoft/Maxwell3D, ANSYS FEA and FLUENT 6.3 CFD software, respectively. Overall, the simulated results reveal that a net flow rate of 52.8 μL/min can be obtained using a diaphragm displacement of 31.5 μm induced by a micro-coil input current of 0.5 A. The impedance pump proposed in this study provides a valuable contribution to the ongoing development of Lab-on-Chips (LoCs) systems. Full article
(This article belongs to the Special Issue Advances in Actuators)
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Open AccessReview Phototactic and Chemotactic Signal Transduction by Transmembrane Receptors and Transducers in Microorganisms
Sensors 2010, 10(4), 4010-4039; https://doi.org/10.3390/s100404010
Received: 28 January 2010 / Revised: 29 March 2010 / Accepted: 9 April 2010 / Published: 20 April 2010
Cited by 19 | PDF Full-text (732 KB) | HTML Full-text | XML Full-text
Abstract
Microorganisms show attractant and repellent responses to survive in the various environments in which they live. Those phototaxic (to light) and chemotaxic (to chemicals) responses are regulated by membrane-embedded receptors and transducers. This article reviews the following: (1) the signal relay mechanisms by
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Microorganisms show attractant and repellent responses to survive in the various environments in which they live. Those phototaxic (to light) and chemotaxic (to chemicals) responses are regulated by membrane-embedded receptors and transducers. This article reviews the following: (1) the signal relay mechanisms by two photoreceptors, Sensory Rhodopsin I (SRI) and Sensory Rhodopsin II (SRII) and their transducers (HtrI and HtrII) responsible for phototaxis in microorganisms; and (2) the signal relay mechanism of a chemoreceptor/transducer protein, Tar, responsible for chemotaxis in E. coli. Based on results mainly obtained by our group together with other findings, the possible molecular mechanisms for phototaxis and chemotaxis are discussed. Full article
(This article belongs to the Special Issue Advances in Transducers)
Open AccessArticle In Situ Roughness Measurements for the Solar Cell Industry Using an Atomic Force Microscope
Sensors 2010, 10(4), 4002-4009; https://doi.org/10.3390/s100404002
Received: 13 January 2010 / Revised: 20 February 2010 / Accepted: 7 April 2010 / Published: 20 April 2010
Cited by 4 | PDF Full-text (762 KB) | HTML Full-text | XML Full-text
Abstract
Areal roughness parameters always need to be under control in the thin film solar cell industry because of their close relationship with the electrical efficiency of the cells. In this work, these parameters are evaluated for measurements carried out in a typical fabrication
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Areal roughness parameters always need to be under control in the thin film solar cell industry because of their close relationship with the electrical efficiency of the cells. In this work, these parameters are evaluated for measurements carried out in a typical fabrication area for this industry. Measurements are made using a portable atomic force microscope on the CNC diamond cutting machine where an initial sample of transparent conductive oxide is cut into four pieces. The method is validated by making a comparison between the parameters obtained in this process and in the laboratory under optimal conditions. Areal roughness parameters and Fourier Spectral Analysis of the data show good compatibility and open the possibility to use this type of measurement instrument to perform in situ quality control. This procedure gives a sample for evaluation without destroying any of the transparent conductive oxide; in this way 100% of the production can be tested, so improving the measurement time and rate of production. Full article
(This article belongs to the Section Chemical Sensors)
Open AccessReview Challenges in the Assembly and Handling of Thin Film Capped MEMS Devices
Sensors 2010, 10(4), 3989-4001; https://doi.org/10.3390/s100403989
Received: 5 January 2010 / Revised: 8 March 2010 / Accepted: 22 March 2010 / Published: 20 April 2010
Cited by 7 | PDF Full-text (809 KB) | HTML Full-text | XML Full-text
Abstract
This paper discusses the assembly challenges considering the design and manufacturability of a Wafer Level Thin Film Package in MEMS applications. The assembly processes are discussed. The loads associated with these processes are illustrated and evaluated. Numerical calculations are combined with experimental observations
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This paper discusses the assembly challenges considering the design and manufacturability of a Wafer Level Thin Film Package in MEMS applications. The assembly processes are discussed. The loads associated with these processes are illustrated and evaluated. Numerical calculations are combined with experimental observations in order to estimate the assembly risks. Our results emphasize the need for concurrent design for assembly. Full article
(This article belongs to the Special Issue Modeling, Testing and Reliability Issues in MEMS Engineering - 2009)
Open AccessArticle Spectral Identification of Lighting Type and Character
Sensors 2010, 10(4), 3961-3988; https://doi.org/10.3390/s100403961
Received: 22 February 2010 / Revised: 12 March 2010 / Accepted: 6 April 2010 / Published: 20 April 2010
Cited by 95 | PDF Full-text (1626 KB) | HTML Full-text | XML Full-text
Abstract
We investigated the optimal spectral bands for the identification of lighting types and the estimation of four major indices used to measure the efficiency or character of lighting. To accomplish these objectives we collected high-resolution emission spectra (350 to 2,500 nm) for forty-three
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We investigated the optimal spectral bands for the identification of lighting types and the estimation of four major indices used to measure the efficiency or character of lighting. To accomplish these objectives we collected high-resolution emission spectra (350 to 2,500 nm) for forty-three different lamps, encompassing nine of the major types of lamps used worldwide. The narrow band emission spectra were used to simulate radiances in eight spectral bands including the human eye photoreceptor bands (photopic, scotopic, and “meltopic”) plus five spectral bands in the visible and near-infrared modeled on bands flown on the Landsat Thematic Mapper (TM). The high-resolution continuous spectra are superior to the broad band combinations for the identification of lighting type and are the standard for calculation of Luminous Efficacy of Radiation (LER), Correlated Color Temperature (CCT) and Color Rendering Index (CRI). Given the high cost that would be associated with building and flying a hyperspectral sensor with detection limits low enough to observe nighttime lights we conclude that it would be more feasible to fly an instrument with a limited number of broad spectral bands in the visible to near infrared. The best set of broad spectral bands among those tested is blue, green, red and NIR bands modeled on the band set flown on the Landsat Thematic Mapper. This set provides low errors on the identification of lighting types and reasonable estimates of LER and CCT when compared to the other broad band set tested. None of the broad band sets tested could make reasonable estimates of Luminous Efficacy (LE) or CRI. The photopic band proved useful for the estimation of LER. However, the three photoreceptor bands performed poorly in the identification of lighting types when compared to the bands modeled on the Landsat Thematic Mapper. Our conclusion is that it is feasible to identify lighting type and make reasonable estimates of LER and CCT using four or more spectral bands with minimal spectral overlap spanning the 0.4 to 1.0 um region. Full article
(This article belongs to the Section Chemical Sensors)
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Open AccessArticle Greatly Improved Small Inductance Measurement Using Quartz Crystal Parasitic Capacitance Compensation
Sensors 2010, 10(4), 3954-3960; https://doi.org/10.3390/s100403954
Received: 3 February 2010 / Revised: 23 March 2010 / Accepted: 23 March 2010 / Published: 20 April 2010
Cited by 12 | PDF Full-text (145 KB) | HTML Full-text | XML Full-text
Abstract
Generally, quartz crystal inductance frequency pulling in oscillators is very low and therefore is not often used in practice. The new method of improving frequencypullability uses inductance to compensate for quartz stray capacitances. To this end, a special AT fundamental quartz crystal working
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Generally, quartz crystal inductance frequency pulling in oscillators is very low and therefore is not often used in practice. The new method of improving frequencypullability uses inductance to compensate for quartz stray capacitances. To this end, a special AT fundamental quartz crystal working near the antiresonance frequency is selected. By modifying its equivalent circuit with load inductance and series tuning capacitance, the magnetic sensing of the circuit can be highly improved. The experimental results show that the new approach using the quartz crystal stray capacitance compensation method increases the frequency pulling range (from ≅ 2 kHz/mH to ≅ 600 kHz/mH) by × 300 depending on the type of oscillator, making possible the measurement of nano-magnetic changes. Full article
(This article belongs to the Special Issue Advances in Transducers)
Open AccessArticle A Monitoring and Advisory System for Diabetes Patient Management Using a Rule-Based Method and KNN
Sensors 2010, 10(4), 3934-3953; https://doi.org/10.3390/s100403934
Received: 25 January 2010 / Revised: 17 March 2010 / Accepted: 30 March 2010 / Published: 19 April 2010
Cited by 8 | PDF Full-text (936 KB) | HTML Full-text | XML Full-text
Abstract
Diabetes is difficult to control and it is important to manage the diabetic’s blood sugar level and prevent the associated complications by appropriate diabetic treatment. This paper proposes a system that can provide appropriate management for diabetes patients, according to their blood sugar
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Diabetes is difficult to control and it is important to manage the diabetic’s blood sugar level and prevent the associated complications by appropriate diabetic treatment. This paper proposes a system that can provide appropriate management for diabetes patients, according to their blood sugar level. The system is designed to send the information about the blood sugar levels, blood pressure, food consumption, exercise, etc., of diabetes patients, and manage the treatment by recommending and monitoring food consumption, physical activity, insulin dosage, etc., so that the patient can better manage their condition. The system is based on rules and the K Nearest Neighbor (KNN) classifier algorithm, to obtain the optimum treatment recommendation. Also, a monitoring system for diabetes patients is implemented using Web Services and Personal Digital Assistant (PDA) programming. Full article
Open AccessArticle BARI+: A Biometric Based Distributed Key Management Approach for Wireless Body Area Networks
Sensors 2010, 10(4), 3911-3933; https://doi.org/10.3390/s100403911
Received: 6 February 2010 / Revised: 6 March 2010 / Accepted: 7 April 2010 / Published: 16 April 2010
Cited by 30 | PDF Full-text (472 KB) | HTML Full-text | XML Full-text
Abstract
Wireless body area networks (WBAN) consist of resource constrained sensing devices just like other wireless sensor networks (WSN). However, they differ from WSN in topology, scale and security requirements. Due to these differences, key management schemes designed for WSN are inefficient and unnecessarily
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Wireless body area networks (WBAN) consist of resource constrained sensing devices just like other wireless sensor networks (WSN). However, they differ from WSN in topology, scale and security requirements. Due to these differences, key management schemes designed for WSN are inefficient and unnecessarily complex when applied to WBAN. Considering the key management issue, WBAN are also different from WPAN because WBAN can use random biometric measurements as keys. We highlight the differences between WSN and WBAN and propose an efficient key management scheme, which makes use of biometrics and is specifically designed for WBAN domain. Full article
(This article belongs to the Section Chemical Sensors)
Open AccessReview Metal Oxide Sensors for Electronic Noses and Their Application to Food Analysis
Sensors 2010, 10(4), 3882-3910; https://doi.org/10.3390/s100403882
Received: 11 March 2010 / Revised: 12 April 2010 / Accepted: 13 April 2010 / Published: 15 April 2010
Cited by 125 | PDF Full-text (394 KB) | HTML Full-text | XML Full-text
Abstract
Electronic noses (E-noses) use various types of electronic gas sensors that have partial specificity. This review focuses on commercial and experimental E-noses that use metal oxide semi-conductors. The review covers quality control applications to food and beverages, including determination of freshness and identification
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Electronic noses (E-noses) use various types of electronic gas sensors that have partial specificity. This review focuses on commercial and experimental E-noses that use metal oxide semi-conductors. The review covers quality control applications to food and beverages, including determination of freshness and identification of contaminants or adulteration. Applications of E-noses to a wide range of foods and beverages are considered, including: meat, fish, grains, alcoholic drinks, non-alcoholic drinks, fruits, milk and dairy products, olive oils, nuts, fresh vegetables and eggs. Full article
(This article belongs to the Special Issue Metal-Oxide Based Nanosensors)
Open AccessArticle Spectroscopic Interpretation of PAH-Spectra in Minerals and Its Possible Application to Soil Monitoring
Sensors 2010, 10(4), 3868-3881; https://doi.org/10.3390/s100403868
Received: 3 February 2010 / Revised: 6 April 2010 / Accepted: 7 April 2010 / Published: 15 April 2010
Cited by 6 | PDF Full-text (597 KB) | HTML Full-text | XML Full-text
Abstract
In order to properly assess the feasibility of using Laser-Induced Fluorescence (LIF) spectroscopy for soil monitoring, the variation of fluorescence intensity due to the heterogeneity and complexity of soil media was investigated. Different soil minerals showed fluorescence spectral structures distinguishable from the contaminants,
[...] Read more.
In order to properly assess the feasibility of using Laser-Induced Fluorescence (LIF) spectroscopy for soil monitoring, the variation of fluorescence intensity due to the heterogeneity and complexity of soil media was investigated. Different soil minerals showed fluorescence spectral structures distinguishable from the contaminants, implying dissimilar interactions or the binding of contaminants on mineral surfaces. More interestingly, solvent and water addition showed different responses in the fluorescence spectral structure showing their effect on the interactions between contaminants and minerals. These results support the claim that the spectral structure contains information on contaminant-mineral interactions; therefore contaminants can be used as a fluorescence probe for these interactions. Full article
(This article belongs to the Special Issue Laser Spectroscopy and Sensing)
Open AccessArticle Carbon Nanotube Integration with a CMOS Process
Sensors 2010, 10(4), 3857-3867; https://doi.org/10.3390/s100403857
Received: 27 January 2010 / Revised: 6 April 2010 / Accepted: 9 April 2010 / Published: 15 April 2010
Cited by 4 | PDF Full-text (1111 KB) | HTML Full-text | XML Full-text
Abstract
This work shows the integration of a sensor based on carbon nanotubes using CMOS technology. A chip sensor (CS) was designed and manufactured using a 0.30 μm CMOS process, leaving a free window on the passivation layer that allowed the deposition of SWCNTs
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This work shows the integration of a sensor based on carbon nanotubes using CMOS technology. A chip sensor (CS) was designed and manufactured using a 0.30 μm CMOS process, leaving a free window on the passivation layer that allowed the deposition of SWCNTs over the electrodes. We successfully investigated with the CS the effect of humidity and temperature on the electrical transport properties of SWCNTs. The possibility of a large scale integration of SWCNTs with CMOS process opens a new route in the design of more efficient, low cost sensors with high reproducibility in their manufacture. Full article
(This article belongs to the Special Issue Advances in Transducers)
Open AccessArticle Design, Fabrication, and Testing of a Bulk Micromachined Inertial Measurement Unit
Sensors 2010, 10(4), 3835-3856; https://doi.org/10.3390/s100403835
Received: 22 February 2010 / Revised: 17 March 2010 / Accepted: 6 April 2010 / Published: 14 April 2010
Cited by 7 | PDF Full-text (582 KB) | HTML Full-text | XML Full-text
Abstract
A bulk micromachined inertial measurement unit (MIMU) is presented in this paper. Three single-axis accelerometers and three single-axis gyroscopes were simultaneously fabricated on a silicon wafer using a bulk micromachining process; the wafer is smaller than one square centimeter. In particular, a global
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A bulk micromachined inertial measurement unit (MIMU) is presented in this paper. Three single-axis accelerometers and three single-axis gyroscopes were simultaneously fabricated on a silicon wafer using a bulk micromachining process; the wafer is smaller than one square centimeter. In particular, a global area optimization method based on the relationship between the sensitivity and layout area was proposed to determine the layout configuration of the six sensors. The scale factors of the X/Y-axis accelerometer and Z-axis accelerometer are about 213.3 mV/g and 226.9 mV/g, respectively. The scale factors of the X/Y-axis gyroscope and Z-axis gyroscope are about 2.2 mV/o/s and 10.8 mV/o/s, respectively. The bias stability of the X/Y-axis gyroscope and the Z-axis gyroscope are about 2135 deg/h and 80 deg/h, respectively. Finally, the resolutions of X/Y-axis accelerometers, Z-axis accelerometers, X/Y-axis gyroscopes, and Z-axis gyroscopes are 0.0012 g/ √Hz, 0.0011 g/ √Hz, 0.314 °/s/ √Hz, and 0.008 °/s/ √Hz, respectively. Full article
(This article belongs to the Special Issue Modeling, Testing and Reliability Issues in MEMS Engineering - 2009)
Open AccessArticle On BER Performance of EBPSK-MODEM in AWGN Channel
Sensors 2010, 10(4), 3824-3834; https://doi.org/10.3390/s100403824
Received: 25 February 2010 / Revised: 30 March 2010 / Accepted: 1 April 2010 / Published: 14 April 2010
Cited by 39 | PDF Full-text (153 KB) | HTML Full-text | XML Full-text
Abstract
In order to satisfy the higher and higher demand for communication systems, an Extended Binary Phase Shift Keying (EBPSK) system with very high spectra efficiency has been proposed. During the research, a special kind of filters was found, which can amplify the signal
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In order to satisfy the higher and higher demand for communication systems, an Extended Binary Phase Shift Keying (EBPSK) system with very high spectra efficiency has been proposed. During the research, a special kind of filters was found, which can amplify the signal characteristics and remove utmost noise, i.e., at the point of the phase jumping corresponding to code “1”, produce the amplitude impulse much higher than code “0”, therefore, the aim of our study was to analyze the BER performance of the impacting filter assisted EBPSK-MODEM. Considering the receiver filtered “0” and “1”signal with Rice amplitude distribution, just having different mean values, so the BER performance of EBPSK is deduced based on the classic detection theory, and compared with the traditional BPSK modulation both in spectra efficiency and in BER performance, which lays the theoretical foundation for the feasibility of Ultra Narrow Band communications based on EBPSK modulation. Full article
(This article belongs to the Section Chemical Sensors)
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Open AccessArticle Optical Sensor for Characterizing the Phase Transition in Salted Solutions
Sensors 2010, 10(4), 3815-3823; https://doi.org/10.3390/s100403815
Received: 11 February 2010 / Revised: 27 February 2010 / Accepted: 17 March 2010 / Published: 14 April 2010
Cited by 9 | PDF Full-text (1779 KB) | HTML Full-text | XML Full-text
Abstract
We propose a new optical sensor to characterize the solid-liquid phase transition in salted solutions. The probe mainly consists of a Raman spectrometer that extracts the vibrational properties from the light scattered by the salty medium. The spectrum of the O-H stretching band
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We propose a new optical sensor to characterize the solid-liquid phase transition in salted solutions. The probe mainly consists of a Raman spectrometer that extracts the vibrational properties from the light scattered by the salty medium. The spectrum of the O-H stretching band was shown to be strongly affected by the introduction of NaCl and the temperature change as well. A parameter SD defined as the ratio of the integrated intensities of two parts of this band allows to study the temperature and concentration dependences of the phase transition. Then, an easy and efficient signal processing and the exploitation of a modified Boltzmann equation give information on the phase transition. Validations were done on solutions with varying concentration of NaCl. Full article
(This article belongs to the Special Issue Laser Spectroscopy and Sensing)
Open AccessArticle Alternative Sensor System and MLP Neural Network for Vehicle Pedal Activity Estimation
Sensors 2010, 10(4), 3798-3814; https://doi.org/10.3390/s100403798
Received: 19 January 2010 / Revised: 21 February 2010 / Accepted: 22 March 2010 / Published: 14 April 2010
Cited by 7 | PDF Full-text (562 KB) | HTML Full-text | XML Full-text
Abstract
It is accepted that the activity of the vehicle pedals (i.e., throttle, brake, clutch) reflects the driver’s behavior, which is at least partially related to the fuel consumption and vehicle pollutant emissions. This paper presents a solution to estimate the driver activity regardless
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It is accepted that the activity of the vehicle pedals (i.e., throttle, brake, clutch) reflects the driver’s behavior, which is at least partially related to the fuel consumption and vehicle pollutant emissions. This paper presents a solution to estimate the driver activity regardless of the type, model, and year of fabrication of the vehicle. The solution is based on an alternative sensor system (regime engine, vehicle speed, frontal inclination and linear acceleration) that reflects the activity of the pedals in an indirect way, to estimate that activity by means of a multilayer perceptron neural network with a single hidden layer. Full article
Open AccessReview Optoelectronic Capillary Sensors in Microfluidic and Point-of-Care Instrumentation
Sensors 2010, 10(4), 3771-3797; https://doi.org/10.3390/s100403771
Received: 15 February 2010 / Revised: 10 March 2010 / Accepted: 30 March 2010 / Published: 14 April 2010
Cited by 24 | PDF Full-text (489 KB) | HTML Full-text | XML Full-text
Abstract
This paper presents a review, based on the published literature and on the authors’ own research, of the current state of the art of fiber-optic capillary sensors and related instrumentation as well as their applications, with special emphasis on point-of-care chemical and biochemical
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This paper presents a review, based on the published literature and on the authors’ own research, of the current state of the art of fiber-optic capillary sensors and related instrumentation as well as their applications, with special emphasis on point-of-care chemical and biochemical sensors, systematizing the various types of sensors from the point of view of the principles of their construction and operation. Unlike classical fiber-optic sensors which rely on changes in light propagation inside the fiber as affected by outside conditions, optical capillary sensors rely on changes of light transmission in capillaries filled with the analyzed liquid, which opens the possibility of interesting new applications, while raising specific issues relating to the construction, materials and instrumentation of those sensors. Full article
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Open AccessCommunication Development of an Emergency Locking Unit for a Belt-In-Seat (BIS) System Using a MEMS Acceleration Sensor
Sensors 2010, 10(4), 3759-3770; https://doi.org/10.3390/s100403759
Received: 1 February 2010 / Revised: 7 April 2010 / Accepted: 8 April 2010 / Published: 14 April 2010
PDF Full-text (1261 KB) | HTML Full-text | XML Full-text
Abstract
This paper proposes an emergency locking unit (ELU) for a seat belt retractor which is mounted on the back frame of a vehicle seat. The proposed unit uses a recliner sensor based on a MEMS acceleration sensor and solenoid mechanism. The seat has
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This paper proposes an emergency locking unit (ELU) for a seat belt retractor which is mounted on the back frame of a vehicle seat. The proposed unit uses a recliner sensor based on a MEMS acceleration sensor and solenoid mechanism. The seat has an upper frame supported to tilt on a lower frame. The retractor in belt in seat (BIS) system is supported by the upper frame. The proposed recliner sensor based on a MEMS acceleration sensor comprises orientation means for maintaining a predetermined orientation of emergency relative to the lower frame independently of the force of gravity when the upper frame tilts on the lower frame. Experimental results show that the developed recliner sensor unit operates effectively with respect to rollover angles. Thus, the developed unit will have a considerable potential to offer a new design concept in BIS system. Full article
(This article belongs to the Section Chemical Sensors)
Open AccessArticle Error Analysis in a Stereo Vision-Based Pedestrian Detection Sensor for Collision Avoidance Applications
Sensors 2010, 10(4), 3741-3758; https://doi.org/10.3390/s100403741
Received: 25 January 2010 / Revised: 18 March 2010 / Accepted: 23 March 2010 / Published: 13 April 2010
Cited by 23 | PDF Full-text (910 KB) | HTML Full-text | XML Full-text
Abstract
This paper presents an analytical study of the depth estimation error of a stereo vision-based pedestrian detection sensor for automotive applications such as pedestrian collision avoidance and/or mitigation. The sensor comprises two synchronized and calibrated low-cost cameras. Pedestrians are detected by combining a
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This paper presents an analytical study of the depth estimation error of a stereo vision-based pedestrian detection sensor for automotive applications such as pedestrian collision avoidance and/or mitigation. The sensor comprises two synchronized and calibrated low-cost cameras. Pedestrians are detected by combining a 3D clustering method with Support Vector Machine-based (SVM) classification. The influence of the sensor parameters in the stereo quantization errors is analyzed in detail providing a point of reference for choosing the sensor setup according to the application requirements. The sensor is then validated in real experiments. Collision avoidance maneuvers by steering are carried out by manual driving. A real time kinematic differential global positioning system (RTK-DGPS) is used to provide ground truth data corresponding to both the pedestrian and the host vehicle locations. The performed field test provided encouraging results and proved the validity of the proposed sensor for being used in the automotive sector towards applications such as autonomous pedestrian collision avoidance. Full article
Open AccessArticle A Multiwell Electrochemical Biosensor for Real-Time Monitoring of the Behavioural Changes of Cells in Vitro
Sensors 2010, 10(4), 3732-3740; https://doi.org/10.3390/s100403732
Received: 2 March 2010 / Revised: 1 April 2010 / Accepted: 6 April 2010 / Published: 13 April 2010
Cited by 4 | PDF Full-text (555 KB) | HTML Full-text | XML Full-text
Abstract
We report the development of a multiwell biosensor for detecting changes in the electrochemical open circuit potential (OCP) generated by viable human cells in vitro. The instrument features eight culture wells; each containing three gold sensors around a common silver/silver chloride reference
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We report the development of a multiwell biosensor for detecting changes in the electrochemical open circuit potential (OCP) generated by viable human cells in vitro. The instrument features eight culture wells; each containing three gold sensors around a common silver/silver chloride reference electrode, prepared using screen-printed conductive inks. The potential applications of the device were demonstrated by monitoring rheumatoid synovial fibroblasts (RSF) and HepG2 hepatocarcinoma cells in response to chemical and biological treatments. This technology could provide an alternative to conventional end-point assays used in the fields of chemotherapy, toxicology and drug discovery. Full article
(This article belongs to the Special Issue State-of-the-Art Sensors Technology in the UK)
Open AccessArticle Authentication and Key Establishment in Dynamic Wireless Sensor Networks
Sensors 2010, 10(4), 3718-3731; https://doi.org/10.3390/s100403718
Received: 8 March 2010 / Revised: 6 April 2010 / Accepted: 6 April 2010 / Published: 13 April 2010
Cited by 22 | PDF Full-text (326 KB) | HTML Full-text | XML Full-text
Abstract
When a sensor node roams within a very large and distributed wireless sensor network, which consists of numerous sensor nodes, its routing path and neighborhood keep changing. In order to provide a high level of security in this environment, the moving sensor node
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When a sensor node roams within a very large and distributed wireless sensor network, which consists of numerous sensor nodes, its routing path and neighborhood keep changing. In order to provide a high level of security in this environment, the moving sensor node needs to be authenticated to new neighboring nodes and a key established for secure communication. The paper proposes an efficient and scalable protocol to establish and update the authentication key in a dynamic wireless sensor network environment. The protocol guarantees that two sensor nodes share at least one key with probability 1 (100%) with less memory and energy cost, while not causing considerable communication overhead. Full article
Open AccessArticle A New Automatic System for Angular Measurement and Calibration in Radiometric Instruments
Sensors 2010, 10(4), 3703-3717; https://doi.org/10.3390/s100403703
Received: 1 February 2010 / Revised: 19 March 2010 / Accepted: 30 March 2010 / Published: 13 April 2010
Cited by 4 | PDF Full-text (371 KB) | HTML Full-text | XML Full-text
Abstract
This paper puts forward the design, construction and testing of a new automatic system for angular-response measurement and calibration in radiometric instruments. Its main characteristics include precision, speed, resolution, noise immunity, easy programming and operation. The developed system calculates the cosine error of
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This paper puts forward the design, construction and testing of a new automatic system for angular-response measurement and calibration in radiometric instruments. Its main characteristics include precision, speed, resolution, noise immunity, easy programming and operation. The developed system calculates the cosine error of the radiometer under test by means of a virtual instrument, from the measures it takes and through a mathematical procedure, thus allowing correcting the radiometer with the aim of preventing cosine error in its measurements. Full article
(This article belongs to the Section Chemical Sensors)
Open AccessReview Quantitative Modeling of Coupled Piezo-Elastodynamic Behavior of Piezoelectric Actuators Bonded to an Elastic Medium for Structural Health Monitoring: A Review
Sensors 2010, 10(4), 3681-3702; https://doi.org/10.3390/s100403681
Received: 6 January 2010 / Revised: 16 March 2010 / Accepted: 31 March 2010 / Published: 13 April 2010
Cited by 42 | PDF Full-text (947 KB) | HTML Full-text | XML Full-text
Abstract
Elastic waves, especially guided waves, generated by a piezoelectric actuator/sensor network, have shown great potential for on-line health monitoring of advanced aerospace, nuclear, and automotive structures in recent decades. Piezoelectric materials can function as both actuators and sensors in these applications due to
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Elastic waves, especially guided waves, generated by a piezoelectric actuator/sensor network, have shown great potential for on-line health monitoring of advanced aerospace, nuclear, and automotive structures in recent decades. Piezoelectric materials can function as both actuators and sensors in these applications due to wide bandwidth, quick response and low costs. One of the most fundamental issues surrounding the effective use of piezoelectric actuators is the quantitative evaluation of the resulting elastic wave propagation by considering the coupled piezo-elastodynamic behavior between the actuator and the host medium. Accurate characterization of the local interfacial stress distribution between the actuator and the host medium is the key issue for the problem. This paper presents a review of the development of analytical, numerical and hybrid approaches for modeling of the coupled piezo-elastodynamic behavior. The resulting elastic wave propagation for structural health monitoring is also summarized. Full article
(This article belongs to the Special Issue Advances in Actuators)
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