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Sensors Journal, IEEE

Issue 10 • Date Oct. 2008

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Displaying Results 1 - 21 of 21
  • Table of contents

    Page(s): 1613 - 1614
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    Freely Available from IEEE
  • High Pressure Sensor Based on Fiber Bragg Grating and Carbon Fiber Laminated Composite

    Page(s): 1615 - 1619
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (174 KB) |  | HTML iconHTML  

    A simple anisotropic structure made by carbon fiber laminated composite for fabricating a high pressure sensor is reported. A pressure sensor with good sensitivity over a broad measurement range is fabricated by using fiber Bragg grating and the anisotropic carbon fiber laminated composite structure. The characteristic responses of pressure and temperature of the new pressure sensor are analyzed. Experimental data show that when the pressure changes from 0 to 70 MPa, the wavelength shift of the fiber Bragg grating pressure sensor is up to 7 nm, corresponding to a sensitivity of 10 kPa/pm. View full abstract»

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  • A New Low Cost Linear Resolver Converter

    Page(s): 1620 - 1627
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    A new low cost converter topology is proposed for sinusoidal position encoders. The converter enables determination of the angle from the sine and cosine signals of the encoder. When used with resolvers, the implementation of the present scheme takes advantage of the available excitation signal used to operate the device. This trigonometric reference signal is optimally used to generate an analogue signal equivalent to a digital look-up table (LUT). This enables determination of the mechanical angle without using LUT, A/D, and D/A converters. The scheme is optimized in order to achieve highest possible precision. Beside simplicity of its implementation, the proposed converter offers the advantage of robustness to amplitude fluctuation of the transducer excitation signal. The converter was implemented using ordinary low-cost analog components. The theory of operation, computer simulation, and experimental results are given. View full abstract»

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  • A Study of the Electrochemical Behavior of Poly [N-Vinyl Carbazole] Formed on Carbon-Fiber Microelectrodes and Its Response to Dopamine

    Page(s): 1628 - 1639
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (2343 KB) |  | HTML iconHTML  

    N-vinyl carbazole (NVCz) random polymers were electrochemically coated onto micron-size carbon fibers in lithium perchlorate/acetonitrile $({hbox {LiClO}}_{4} /{hbox {ACN}})$, sodium perchlorate/acetonitrile $({hbox {NaClO}}_{4} /{hbox {ACN}})$, and tetraethylammonium tetrafluoroborate/acetonitrile $({hbox {TEABF}}_{4} /{hbox {ACN}})$ solutions in order to form dopamine-sensing layers on the carbon fiber microelectrodes (CFMEs). The resulting micron-thick polymer films were characterized by using scanning electron microscopy and Fourier transform infrared reflectance spectroscopy. Electrocoating of polymeric film was performed by three different electrochemical methods such as cyclic voltammetry and chronoamperometric and chronopotentiometric polarizations. These modified CFMEs were tested against dopamine by applying only cyclovoltammetric techniques. Under optimum experimental conditions, the electrode shows a reversible and stable behavior during 24 days in a 0.1-M ${hbox {TEABF}}_{4} /{hbox {ACN}}$ solution and, hence, can be considered as a promising sensor for dopamine detection. The dopamine detection limit as low as 0.01 nM (3S/N) was obtained for the polymer film formed among applied cyclic voltammetry, chronoamperometry, and chronopotentiometry. The polymer film was demonstrated to offer high selectivity toward dopamine detection in the presence of ascorbic acid. View full abstract»

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  • A Novel Capacitive Safety Device for Target Localization and Identification

    Page(s): 1640 - 1647
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    A novel capacitive device dedicated to the safety of people working on automated production sites has been developed. It can be implemented on an articulated mechanical system (robot, press) to estimate the distance between sensors that are fixed on such a system and a mobile target. An interdigital sensor has been fabricated to identify the target nature among them (human beings or objects). The variable geometry of the system is taken into account as well as its motion relatively towards the ground by means of an ingenious sensitive element design. Furthermore, the sensors are made of conducting paint, thus providing low weight and negligible space hindrance devices. Results show this novel low-cost sensing setup has a great potential to estimate the distance and to discriminate targets. View full abstract»

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  • Robust Algorithm for a Noncontact Single Chip Input Device With Four Degrees of Freedom

    Page(s): 1648 - 1655
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1121 KB) |  | HTML iconHTML  

    This paper presents an input device with four degrees of freedom that can be used for various applications. The system comprises an array of lateral Hall elements implemented on a single chip in standard CMOS technology. A computationally efficient evaluation algorithm is presented that can be easily implemented on a simple microcontroller or dedicated hardware within the integrated circuit. View full abstract»

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  • A Disposable Optical Fiber-Based Capillary Probe for Sensing Lead Ions

    Page(s): 1656 - 1662
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    A disposable capillary-based probe using optical fiber technology to create a compact and portable configuration has been designed for sensing lead ions. It is based around a glass capillary tube pretreated with a fluorophore with high sensitivity and selectivity towards lead ions. The capillary tube makes use of capillary action to uptake the same sample volume for each single-shot measurement. The probe response to lead has been shown to be in the 20–150 $mu {hbox {M}}$ concentration range with a dynamic range of 20–80 $mu {hbox {M}}$. A relative standard deviation of ${sim {hbox {6}}}%$ was obtained from a series of results on different probes. This preliminary work is essentially a proof-of-principle for a probe design in which chemical indicators that cannot be immobilized onto a solid support can still be adapted for optical fiber sensing without any chemical modification. The disposable capillary probe provides a mechanical support and protection to the fluorophore without the use of membranes, thus avoiding problems with leaching. As far as the authors are aware, this is the first time that an optical fiber sensor using a fluorescent indicator for optical lead sensing in an organic solution has been produced. View full abstract»

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  • Model for Studies of Lateral Photovoltaic Effect in Polymeric Semiconductors

    Page(s): 1663 - 1671
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    We present here a discrete circuit spreading impedance network model for highly disordered semiconducting polymeric Schottky devices. Qualitative arguments are presented to correlate the parameters of the spreading function, which represents the network connectivity in the model, to the underlying morphology of the polymer. A detailed theoretical study of the lateral charge transport in organic Schottky devices is carried out using the model. We observe and analyze the dependence of the lateral photovoltage (LPV) on the polymer morphology, incident power, material specific Schottky junction parameters and the modulation frequency. The model is shown to account for a variety of experimental observations on poly-(3-hexylthiophene) and poly-[2-${hbox {methoxy}}$,5-(2-${hbox {ethylhexoxy}})$-1, 4- ${hbox {phenylene~vinylene}}$]-based position sensitive devices, while being physically transparent and computationally efficient. Using the model, we highlight those parameter regimes that would be optimal for position sensing applications. View full abstract»

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  • Effects of Operational Frequency Scaling in Multi-Degree of Freedom MEMS Gyroscopes

    Page(s): 1672 - 1680
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    This paper analyzes the design tradeoffs associated with increasing the operational frequency of single-axis microelectromechanical systems (MEMS) gyroscopes with multi-degree of freedom (DOF) sense modes. Previously, a z-axis multi-DOF gyroscope (1-DOF drive, 2-DOF sense) was shown to be robust to thermal variations using a prototype with a subkilohertz operational frequency; automotive applications, however, require higher frequencies of operation to suppress the effect of ambient vibrations. To study scaling effects on the multi-DOF concept, design equations were obtained in terms of operational frequency. These revealed a constraint on system parameters that introduces two scaling methods that dictate a tradeoff between gain, die size, and sense capacitance. Second generation multi-DOF gyroscopes were designed and fabricated resulting in 0.7-, 3.1-, and 5.1-kHz devices with smaller sense mode resonant frequency spacings than previously achievable. Experimental rate characterization resulted in scale factors of 14.2, 5.08, and 2.34 mu V/deg /s, respectively, confirming the predicted scaling effects while also demonstrating the feasibility of increased frequency multi-DOF gyroscopes. View full abstract»

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  • Contaminant Cloud Boundary Monitoring Using Network of UAV Sensors

    Page(s): 1681 - 1692
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    In this paper, we describe research work currently being undertaken to detect, model, and track the shape of a contaminant cloud boundary using air borne sensor swarms. A model of the contaminant cloud boundary is first developed using a splinegon, defined by a set of vertices linked by segments of constant curvature. This model is then used in an estimator to predict the evolution of the contaminant cloud. This approach is efficient in that only the vertices and segment curvatures are required to define the cloud boundary, rather than using a distribution function to represent the dispersion density. View full abstract»

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  • GaN Metal–Semiconductor–Metal Photodetectors With SiN/GaN Nucleation Layer

    Page(s): 1693 - 1697
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (509 KB) |  | HTML iconHTML  

    In this paper, GaN metal-semiconductor-metal (MSM) photodetectors with SiN/GaN nucleation layer were proposed and fabricated. Compared with the GaN MSM photodetector with conventional single low-temperature GaN nucleation layer, it was found that we achieved much smaller dark current and much lower bias-dependent photocurrent. We also achieved much lower bias-dependent spectral response and larger ratio of photoresponse at 360-450 nm from the photodetector with SiN/GaN nucleation layer. Furthermore, it was found that we can significantly reduce noise-equivalent power (NEP) and enhance normalized detectivity by using the SiN/GaN nucleation layer. View full abstract»

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  • Micromachined Fiber Optical Sensor for In Vivo Measurement of Optical Properties of Human Skin

    Page(s): 1698 - 1703
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1221 KB) |  | HTML iconHTML  

    In this paper, we present the design, fabrication, and testing of a new micromachined fiber optic sensor probe to conduct oblique incidence diffuse reflectance spectrometry (OIDRS) for in vivo estimation of optical properties of human skins. The probe consists of three source fibers, two linear array of collection fibers, and four micromachined positioning devices for accurate alignment of the fibers. Micromachining plays a significant role in the probe development by enabling device miniaturization, low-cost fabrication, and precise assembly. The new probe has been successfully used to estimate the absorption and scattering coefficient spectra of skin with an optical spectrum between 455 and 765 nm. View full abstract»

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  • Processing and Characterization of a MOS-Type Tetra Lateral Position Sensitive Detector With Indium Tin Oxide Gate Contact

    Page(s): 1704 - 1709
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    A 2-D tetra lateral position sensitive detector (PSD) based on the metal-oxide-semiconductor (MOS) principle has been manufactured and characterized. The active area of the device is 5 mm times 5 mm and the intention is to use the central 4 mm times 4 mm for low nonlinearity measurements. The gate contact is made of indium tin oxide (ITO) that is a degenerate electrically conducting semiconductor, which, in addition, is also transparent in the visible part of the spectrum. The use of a MOS structure results in a processing with no necessity to use implantation or diffusion in order to make the resistive p-layer as in a conventional p-n junction lateral effect PSD. Position measurements show good linearity in the middle 4 mm times 4 mm area. Within the middle 2.1 mm times 2.1 mm, the nonlinearity is within plusmn1.7% of the active area with a position detection error of maximum 60 mum. Measured MOS IV characteristics are compared to a level 3 spice model fit and show good agreement. The threshold voltage is determined to be -0.03 V. Responsivity measurements show a high sensitivity in the visible spectral region. View full abstract»

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  • A WSN-Based Intelligent Light Control System Considering User Activities and Profiles

    Page(s): 1710 - 1721
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    Recently, wireless sensor networks (WSNs) have been widely discussed in many applications. In this paper, we propose a WSN-based intelligent light control system for indoor environments. Wireless sensors are responsible for measuring current illuminations. Two kinds of lighting devices, namely, whole lighting and local lighting devices, are used to provide background and concentrated illuminations, respectively. Users may have various illumination requirements according to their activities and profiles. An illumination requirement is as the combination of background and concentrated illumination demands and users' locations. We consider two requirement models, namely, binary satisfaction and continuous satisfaction models, and propose two decision algorithms to determine the proper illuminations of devices and to achieve the desired optimization goals. Then, a closed-loop device control algorithm is applied to adjust the illumination levels of lighting devices. The prototyping results verify that our ideas are practical and feasible. View full abstract»

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  • Effects of Synchronous Demodulation in Vibratory MEMS Gyroscopes: A Theoretical Study

    Page(s): 1722 - 1733
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    In a vibratory microgyroscope, the synchronous demodulation of the secondary (sense) resonator output is a critical part of the signal processing. This is because different nonidealities can corrupt the resulting signals, including the angular velocity information. The effect of these nonidealities is revealed in the demodulation process. In this paper, issues related to synchronous demodulation are discussed. A detailed analysis of the effects caused by various nonidealities is provided. The nonidealities considered are as follows: delay in the displacement-to-voltage conversion, differences in the transfer functions of the two sidebands in the force-to-displacement conversion in the secondary resonator, nonlinearities in the displacement-to-voltage conversion, and mechanical-thermal noise. In addition to the analysis of the nonidealities, a general insight into the demodulation process, which is necessary for a successful system-level design, is provided. View full abstract»

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  • Comparison of Methods for Estimating the Conversion Gain of CMOS Active Pixel Sensors

    Page(s): 1734 - 1744
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    The use of complimentary metal-oxide-semiconductor (CMOS) active pixel sensors (APS) in scientific applications is becoming increasingly widespread and as a result, attempts to quantify their absolute performance via the conversion gain parameter K(epsiv_/DN) are now common. The inherent non- linearity of CMOS APS response means that the gold standard "mean-variance" and "photon-transfer" methods for establishing sensor conversion gain cannot automatically be used. Recently, two alternative methods have been proposed for deriving the conversion gain of APS. These methods appear to produce good results but have yet to be directly compared using results from a single sensor. This paper uses a single data set from a prototype APS to provide an absolute comparison of the performance of these nonlinear methods with respect to each other, and to standard linear methods. It also proposes a measurement procedure to enable evaluation of any APS. The prototype APS "Vanilla" produced by the RC-UK MI-3 consortium was illuminated uniformly at 65 intensity levels between dark and saturation. Results for Vanilla from linear methods substantially overestimate the sensor full well capacity (p = 0.003) to be (94.1 plusmn 1.4) X 103e- and (91.2 plusmn 1.4) x 103e-, respectively, when compared to nonlinear analysis methods. They also slightly underestimate the sensor read noise (p = 0.016) to be 51.8 plusmn 0.7e_ and 52.3 plusmn 0.7e~, respectively. The results obtained from both nonlinear estimation (NLE) and nonlinear compensation (NLC) are in good agreement, predicting read noise of54.8plusmn0.3e- and 55.4 plusmn 0.2e- and full well capacity of (72.0 plusmn 0.3) x 103e- and (72.6 plusmn 0.3) X 103e-, respectively. Results indicate that nonlinear analysis should be performed for APSs. View full abstract»

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  • Software-Defined Six-Port Radar Technique for Precision Range Measurements

    Page(s): 1745 - 1751
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    A software-defined radar measurement system on the basis of a six-port receiver technique is proposed and described in this paper. The system makes use of a hybrid scheme of two performance-complementary operating modes, namely, frequency-modulated continuous-wave (FMCW) and two-tone continuous-wave signals. Generally, the FMCW-based measurement technique is deployed to give an approximate range value of target while the two-tone continuous-wave (CW)-based measurement technique can accurately determine the range that may, however, be ambiguous. The six-port circuit is used for the receiver as a precision phase detector in two-tone CW function and at the same time as a mixer in FMCW function. Various waveforms are generated in direct digital synthesizers and processed by different algorithms in a digital signal processor. The switching between the frequency-modulated CW and two-tone CW functions is controlled by software to improve the resolution and ensure a reliable operation. A system prototype is designed and made for a C-band demonstration. The Schottky diodes used as power detectors in the six-port are calibrated so that they can be used beyond the square-law region, thus allowing a higher power level and a better dynamic range. Measured results validate the proposed software-defined platform and accurate range results are confirmed. View full abstract»

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  • IEEE Sensors 2008

    Page(s): 1752
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    Freely Available from IEEE
  • IEEE Sensors Council Information

    Page(s): 1753
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    Freely Available from IEEE
  • [Front cover]

    Page(s): 1754
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    Freely Available from IEEE
  • IEEE Sensors Journal publication information

    Page(s): 1755
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    Freely Available from IEEE

Aims & Scope

The IEEE Sensors Journal is a peer-reviewed, monthly online/print  journal devoted to sensors and sensing phenomena

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Editor-in-Chief
Krikor Ozanyan
University of Manchester
Manchester, M13 9PL, U.K.