By Topic

Sensors Journal, IEEE

Issue 4 • Date Aug. 2003

Filter Results

Displaying Results 1 - 25 of 26
  • Temperature correction to chemoresistive sensors in an e-NOSE-ANN system

    Page(s): 484 - 489
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (465 KB)  

    The influence of the temperature coefficient of resistance in the chemoresistive response of inherently conductive polymer (ICP) sensors in the performance of an artificial neural network (ANN) e-natural olfactory sensor emulator (e-NOSE) system is evaluated. Temperature was found to strongly influence the response of the chemoresistors, even over modest ranges (ca. 2/spl deg/C). An e-NOSE array of eight ICP sensor elements, a relative humidity (RH/spl plusmn/0.1%) sensor, and a resistance temperature device (RTD/spl plusmn/0.1/spl deg/C) was tested at five different RH levels while the temperature was allowed to vary with the ambient. A temperature correction algorithm based on the temperature coefficient of resistance /spl beta/ for each material was independently and empirically determined then applied to the raw sensor data prior to input to the ANN. Conversely, uncorrected data was also passed to the ANN. The performance of the ANN was evaluated by determining the error found between the actual humidity versus the calculated humidity. The error obtained using raw input sensor data was found to be 10.5% and using temperature corrected data, 9.3%. This negligible difference demonstrates that the ANN was capable of adequately addressing the temperature dependence of the chemoresistive sensors once temperature was inclusively passed to the ANN. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Fatigue testing of a composite propeller blade using fiber-optic strain sensors

    Page(s): 393 - 399
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (540 KB)  

    The performance of surface-mounted extrinsic Fabry-Perot interferometric (EFPI) sensors during a seventeen-million-cycle, high-strain fatigue test is reported. Fiber-optic strain measurements did not degrade during the test. The sensors were applied to a composite propeller blade subject to a constant axial load and a cyclic bending load. Strain measurements were taken at four blade locations using two types of EFPI sensors and co-located electrical resistance strain gages. Static and dynamic strain measurements were taken daily during the 65 days of this standard propeller-blade test. All fiber-optic sensors survived the fatigue test while most of the resistive gages failed. The suitability of fiber-optic monitoring for fatigue testing and other high-cycle monitoring is demonstrated. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Bulk acoustic wave affinity biosensor for genetically modified organisms detection

    Page(s): 369 - 375
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (467 KB) |  | HTML iconHTML  

    Bulk acoustic waves have been applied as affinity sensors. In particular, a nucleic acid sensor for hybridization studies has been developed and applied for detecting DNA target sequences in solution. A DNA probe is immobilized on the sensor surface while the target sequence is free in solution; the interaction between the two complementary strands (hybridization) is followed in real-time, without the use of any label. The system has been applied to analytical problems, i.e., genetically modified organisms (GMOs) detection. The probe was complementary to characteristic DNA sequences present in GMOs. The probe sequences were internal to the sequence of 35S promoter and Nos terminator that are inserted sequences in the genome of the GMO regulating the transgene expression. Two different probe immobilization procedures were characterized to improve the performances of a piezoelectric crystal DNA sensor for GMOs detection: 1) thiol-dextran-streptavidin-biotin procedure and 2) thiol-derivatized probe and blocking thiol procedure. The system has been optimized using synthetic oligonucleotides. The probe immobilization step was monitored by a surface plasmon resonance system. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Application of empirical neural networks to chlorophyll-a estimation in coastal waters using remote optosensors

    Page(s): 376 - 382
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (516 KB) |  | HTML iconHTML  

    This paper presents chlorophyll-a estimation in coastal waters off the Gulf of Finland using remote optosensors. Concurrent remote optosensor data and in situ measurements of water quality were obtained in the study area. Significant correlations were observed between digital values and chlorophyll-a measurements. The results as a case study show that the estimated accuracy of chlorophyll-a retrieval using neural networks is higher than the accuracy of chlorophyll-a estimation using regression analyzes in the area. The study also shows one example why remote optosensors are critical to monitor water quality in coastal areas such as the Gulf of Finland. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Strain-sensing fabrics for wearable kinaesthetic-like systems

    Page(s): 460 - 467
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (805 KB) |  | HTML iconHTML  

    In recent years, an innovative technology based on polymeric conductors and semiconductors has undergone rapid growth. These materials offer several advantages with respect to metals and inorganic conductors: lightness, large elasticity and resilience, resistance to corrosion, flexibility, impact strength, etc. These properties are suitable for implementing wearable devices. In particular, a sensitive glove able to detect the position and the motion of fingers and a sensorized leotard have been developed. Here, the characterization of the strain-sensing fabric is presented. In the first section, the polymerization process used to realize the strain sensor is described. Then, the thermal and mechanical transduction properties of the strain sensor are investigated and a geometrical parameter to invariantly codify the sensor response during aging is proposed. Finally, a brief outline of ongoing applications is reported. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Comparative analysis of wavelength-multiplexed photonic-sensor networks using fused biconical WDMS

    Page(s): 475 - 483
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (414 KB)  

    Three networks based on fused biconical wavelength division multiplexers (WDMs) and fiber Bragg gratings (FBGs) are theoretically and experimentally demonstrated for photonic-intensity-sensor multiplexing. The aim of replacing standard couplers for WDMs in the power division process is to reduce power losses and improve the robustness of the systems to FBG wavelength shifts. The different network topologies are analyzed both in terms of power budget and crosstalk noise, considering the multiplexing of two fiber-taper displacement sensors. The configuration with one detector for each sensor and the corresponding FBG at the detection end is proven to be the best topology in terms of crosstalk, doubling the peak-isolation value of the WDMs employed and yielding a 37.4 dB optical signal-to-noise ratio for a two-sensor network. Regarding power losses, the optimum configuration locates the FBGs at the sensor heads, thus improving power budget and avoiding additional couplers at the detectors. Both topologies are expanded to multiplex four sensors, with crosstalk identified as the critical factor in these networks. With this limiting parameter, the first configuration has been determined as the most suitable for multiplexing a high number of sensors. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Fiber-optic temperature sensor used for oil well based on semiconductor optical absorption

    Page(s): 400 - 403
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (312 KB) |  | HTML iconHTML  

    This paper describes an optical-fiber sensor developed for temperature measurement under offshore oil well conditions. The sensor exploits the displacement of the optical absorption edge occurring in semiconductors under the influence of temperature variation as a result of temperature-induced energy shifting of conduction band extrema. The structure of the sensor and the measurement principle are described. The common-path reference measurement and node type error compensation technologies are developed. And, the detailed theoretical analysis indicates that the proposed sensor system can effectively improve measurement errors caused by light fluctuation, difference and variation of the detector responsiveness, circuit magnification times, and so on. It proves that this sensor system can be applied under long-term formidable conditions with fairly good measurement stability. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • A comparison of Schottky barrier position-sensitive detectors as a function of light wavelength

    Page(s): 519 - 524
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (548 KB) |  | HTML iconHTML  

    Position-sensitive detectors (PSDs), are single continuous optical sensors that utilize the lateral photovoltaic effect to produce an electrical output that varies linearly with light spot position. This work reports further on the results from Schottky barrier PSDs fabricated from thin films of tantalum, titanium, and aluminum. The optimal thickness of the Schottky metals was determined, trading off light transmissivity and proper Schottky barrier formation. The objective of this work was to determine if devices performed particularly well or poorly under certain light sources and, if so, at what thickness of film. Each device has been tested in one dimension under 5 mW of red laser light, focused broad-band light, as well as filtered red, green, and blue light. It was found that all devices generally responded well to the filtered red light and worst under the green light source. The extent to which this is true depends on the Schottky metal used and its thickness. It was also found that the detector response changed over time. Most interestingly, the tantalum Schottky barrier devices either improved or remained the same while the titanium devices deteriorated noticeably. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Tunable injection current compensation architecture for high fill-factor self-buffered active pixel sensor

    Page(s): 525 - 532
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1353 KB) |  | HTML iconHTML  

    A high fill-factor self-buffered active pixel sensor and a tunable injection current compensation architecture for high dynamic range imager are proposed for scaled standard CMOS technology. The new cell, including a photo diode formed by n-well and p-type substrate and an one-transistor output buffer, shows enhanced characteristics in output voltage swing and sensitivity compared with conventional APS. The imager can achieve fill-factor of 55%, sensitivity of 3.4 V/sec-lux, and large output swing of 2.2 V at VDD=3.3 V for 0.25-μm CMOS technology. In addition, the proposed tunable injection current compensation architecture can improve dynamic range by as much as 40 dB and can be tailor designed to meet various application specifications. A dynamic range of up to 120 dB is projected by simulation results. Experimental results of the new structure, as well as simulated design of the circuit, are presented. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Interface for MEMS-based rotational accelerometer for HDD applications with 2.5 rad/s2 resolution and digital output

    Page(s): 383 - 392
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (747 KB) |  | HTML iconHTML  

    A 0.6 μm BiCMOS interface for microelectromechanical systems (MEMS) based rotational accelerometers is presented. It is housed in an inexpensive standard SO-24 plastic package with a capacitive rotational accelerometer sensor produced using MEMS technology. This sensitive interface chip includes the analog-to-digital conversion, filtering, and interface functions. The analog-to-digital conversion is realized through a single-bit electromechanical Σ-Δ loop able to detect capacitive unbalancing as low as 50 aF (50×10-18 F). The produced bitstream is then processed by a digital chain and made available through a standard 3.3 V (5 V tolerant) three-wire serial bus. The signal bandwidth is about 800 Hz, the sensitivity is 2.5 rad/s2, with a full-scale sinewave of 200 rad/s2 and a signal-to-noise ratio peak of 38 dB over 30-800 Hz. Through the serial bus, it is also possible to program device characteristics including gain, offset, filter performance, and phase delay. The complete sensor is used in a feed-forward compensation scheme to cancel external disturbances acting on computer hard-disk drives so as to steadily keep the read-write heads on track: this allows greater track densities and better speed performance. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Monolithic miniaturized quartz microbalance array and its application to chemical sensor systems for liquids

    Page(s): 361 - 368
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1049 KB) |  | HTML iconHTML  

    We report on the design, fabrication, and application of novel monolithic miniaturized quartz microbalance (QMB) arrays. Up until now, almost all reported resonator arrays (often designated as "electronic noses" or "electronic tongues", respectively, dependent on their application) are assembled from single QMBs. We fabricate arrays with up to 36 QMBs on a single AT-cut quartz blank. Mass sensitive devices based on AT-cut quartz resonators are suitable as (bio)chemical sensors. A frequency shift caused by mass accumulation on the sensor surface increases theoretically with f2, hence the detection limits for the application as chemical sensors should be decreased with increasing frequency. Since the quality factor Q of a quartz crystal decreases with f, the frequency stability is reduced, thus limiting mass sensitivity. The mass sensitivity of resonators with different resonant frequencies was examined by means of electrochemical copper deposition on their surface. Subsequently, the manufactured resonators were coated with different layers (polystyrene, amyl-calix[8]arene, β-cyclodextrine). In order to examine the applicability of such coatings as sensitive layers, their sensitivities to toluene in water were investigated. Moreover, arrays with up to four different resonant frequencies on one chip were fabricated for comparing the resonator behavior of the same coating at different frequencies. In another test setup, different layers were sprayed onto an array of microbalances having all the same resonant frequency. This allowed for comparing the different coating behavior under equivalent test conditions. Arrays were tested for viscosity measurement to find an optimum resonant frequency. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Fundamental study of odor recorder for multicomponent odor using recipe exploration method based on singular value decomposition

    Page(s): 468 - 474
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (509 KB) |  | HTML iconHTML  

    A new method for the odor recorder, electronically recording the recipe of odors or scents made up of many components, was proposed. Although apple flavors have been recorded with a mixture of five components using the odor recorder in previous work, the number of odor components should be increased to expand the applicable range of odors. Since the collinearity problem of the odor sensor array became apparent with the increase of components, a new method based on variable transformation using singular value decomposition was developed in this paper, to extract the effective subspace of the sensor outputs for recipe exploration. As a result, the sensor-array response pattern of the reproduced odor, with the eight-component recipe, almost agreed with that of the target apple flavor. Furthermore, human sensory tests revealed that the smell of the approximated odor was identical to that of the target flavor. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Fabrication of a disposable biosensor for Escherichia Coli O157:H7 detection

    Page(s): 345 - 351
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (614 KB) |  | HTML iconHTML  

    As the safety in the food supply becomes critical, the demand for a rapid, low-volume, and sensitive microbial detection device has dramatically increased. A biosensor based on an electrochemical sandwich immunoassay using polyaniline has been developed for detecting foodborne pathogens, such as Escherichia coli (E. coli) O157:H7. The biosensor is comprised of two types of proteins: capture protein and reporter protein. The capture protein is immobilized on a pad between two electrodes, while the reporter protein is attached to conductive polymers. After adding the sample, the target protein binds to the reporter protein and forms a sandwich complex with the capture protein. The conductive polymer that is attached to the reporter protein serves as a messenger, reporting the amount of target protein captured in the form of an electrical signal. The architecture of the biosensor utilizes a lateral flow format, which allows the liquid sample to move from one pad to another by capillary action. Experiments to evaluate the best construction materials, the optimal polyaniline and antibody concentrations, and the distance between electrodes are highlighted in this paper. Results show that the biosensor could detect approximately 7.8×101 colony forming unit per milliliter of E. coli O157:H7 in 10 min. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Improving the response of a wheel speed sensor by using frequency-domain adaptive filtering

    Page(s): 404 - 413
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (655 KB) |  | HTML iconHTML  

    In this paper, a frequency-domain least-mean-square adaptive filter is used to cancel noise in a wheel speed sensor embedded in a car under performance tests. In this case the relevant signal is buried in a broad-band noise background, where we have little or no prior knowledge of the signal or noise characteristics. The results of the experiments show that the signal of interest and the noise (all forms of interference, deterministic, as well as stochastic) share the same frequency band and that the filter used significantly reduced the noise corrupting the information from the sensor while it left the true signal unchanged from a practical point of view. In this paper, a signal-to-noise ratio improvement higher than 40 dB is achieved. The results of the experiment show the importance of using digital signal processing when dealing with a signal corrupted by noise. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Preparation and gas-sensing characteristics of nanocrystalline spinel zinc ferrite thin films

    Page(s): 435 - 438
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (362 KB) |  | HTML iconHTML  

    Zinc ferrite is a promising sensor material. In this paper, thin films of nanocrystalline zinc ferrite were deposited on alumina substrates by nebulization of a 0.01-M solution of a mixture of ZnCl2 and FeCl3 in ethanol (Zn:Fe=1:2) followed by pyrolysis and annealing in flowing air. The resulting films were characterized by X-ray diffraction and scanning electron microscopy, and the gas-sensing properties of as-deposited films were also investigated. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Comparison of barrel-stave sonar transducer simulations between a coupled FE-BEM and ATILA

    Page(s): 439 - 446
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1146 KB)  

    An acoustic analysis of a barrel-stave sonar transducer has been performed using a coupled finite element-boundary element method developed by the author. The dynamics of the piezoelectric flextensional sonar transducer is modeled in three dimensions and is analyzed with external electrical excitation conditions. Different results are available such as steady-state displacement modes, underwater directivity patterns, resonant frequencies, and transmitting voltage responses. The results of this analysis were then compared and found to be in good agreement to the same analysis performed using ATILA. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • In-line highly sensitive hydrogen sensor based on palladium-coated single-mode tapered fibers

    Page(s): 533 - 537
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (330 KB) |  | HTML iconHTML  

    We report a fiber-optic sensor for detecting low concentrations of hydrogen. The sensor is based on the absorption change of the evanescent fields in a Pd-coated, single-mode tapered fiber. We fabricated a collection of polarization-sensitive and polarization-insensitive devices and we studied the effect of the different parameters on the sensitivity of the device. We found that the sensor's response is wavelength dependent and it can be adjusted with the taper diameter. Dramatic transmission changes were observed when the sensors were exposed to hydrogen concentrations below 4%. We complement the experimental results with theoretical calculations of the attenuation constant of the fundamental fiber-mode. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • A thickness-shear quartz resonator force sensor with dual-mode temperature compensation

    Page(s): 490 - 496
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (377 KB) |  | HTML iconHTML  

    An AT-cut thickness-shear quartz crystal resonator (QXR) has been used as a force sensing and self-temperature-sensing (STS) element to develop a digital output force sensor. The QXR is fixed in a two-line mounting configuration in a cylindrical metal shell by double diaphragms, through which a diametric force proportional to the unknown force is applied to the QXR. The double diaphragms improve the reliability and the mechanical stability of the sensor significantly. In order to increase the measurement range and the sensitivity, the energy trapping-based QXR is cut to a symmetrical, incomplete circular shape to decrease stress concentration. Because operating the QXR in dual-mode excitation allows the separation of force change effects from temperature change effects, force measurement and STS are accomplished simultaneously with the same QXR. The structure and the configuration are optimized with theoretical analysis and FEM. The dual-mode STS and temperature compensation are described in detail, as well as a trimming method to reduce activity dips of AT-cut QXRs. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Use of different sensing materials and deposition techniques for thin-film sensors to increase sensitivity and selectivity

    Page(s): 454 - 459
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (324 KB)  

    The performances of metal oxide semiconducting materials used as gas-sensing detectors depend strongly on their structural and morphological properties. The average grain size has been proved to play a prominent role and better sensor performances were found in polycrystalline films where the grain size is few tens of nm or smaller. On the other hand, thermal treatments during thin-film deposition and/or sample postprocessing could lead to a grain coalescence, thus decreasing the conductivity of the sensing film. Avoiding such a phenomenon, still keeping optimized processing conditions, will increase the sensor performances, maintaining the resistivity at acceptable values. In this work, new gas-sensing materials and new thin-film deposition procedures have been investigated. Aiming to preserve the sensitivity, to enhance selectivity and to reduce the drift, thin films of WO3 and CrTiO3 deposited by pulsed-laser ablation (PLA) and of SnO2 deposited by rheotaxial growth and thermal oxidation techniques were comparatively characterized. Three issues were mainly addressed: the variation of the conductivity as a function of RH, the sensitivity toward benzene, CO, acetone, and NO2, and the selectivity. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • A hygrometer comprising a porous silicon humidity sensor with phase-detection electronics

    Page(s): 414 - 420
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (750 KB)  

    A novel hygrometer is presented, comprising a capacitive humidity sensor with a porous silicon (PS) dielectric and electronics. The adsorption of water vapor by the PS layer leading to change of its effective dielectric constant is modeled with an effective medium approximation (EMA). A simple, but precise, phase-sensitive electronic circuit has been developed. This detects any change of phase of a sinusoidal signal transmitted through the PS dielectric and correlates to ambient humidity. It is outlined how the nonlinear response of the sensor is compensated through piecewise linearization. The sensor is tested in combination with the phase detection circuitry. Excellent linearity over the entire range of relative humidity is achieved. Experimental results show a resolution better than 0.1% and an accuracy of 2% (near the transition region) and better than 0.1% (otherwise). The response time is less than 10 s with good stability. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Optical router for optical fiber sensor networks based on a liquid crystal cell

    Page(s): 513 - 518
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (679 KB) |  | HTML iconHTML  

    Optical fiber sensor networks are evolving rapidly. They are used because of the inert nature of optical fibers allowing no electromagnetic interference and safe applications in inflammable atmospheres; other relevant characteristics are their low weights and wide bandwidths as a transmission medium. In any case, it is very interesting to have specific components such as optical routers for selecting a certain path in a network with no optical to electrical and electrical to optical conversions. In this paper, we propose an all-optical router based on liquid crystals, polarizers, and a spatial split polarization beam splitter. The implemented device is designed to operate with visible light and it has been tested with plastic optical fibers. It has a crosstalk of 14 dB between selected ON channels and nonoperative OFF channels and 11-dB insertion losses. An average switch time of 100 ms is measured. The device checks the optical power level in each channel and, in case of failure, automatically switches to an operative channel while an alarm is activated. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Study of xα-Fe2O3-(1-x)ZrO2 solid solution for low-temperature resistive oxygen gas sensors

    Page(s): 421 - 434
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (997 KB) |  | HTML iconHTML  

    A noble type of oxygen-sensitive and electrical-conductive material, ZrO2-based with α-Fe2O3 thick-film gas sensor, was investigated for low operating temperature. Amorphous-like solid solutions of xα-Fe2O3-(1-x)ZrO2 powders were derived using the high-energy ball milling technique, and their physical and microstructural properties were characterized from DTA, XRD, TEM, and XPS. The oxygen gas-sensing properties of the screen-printed thick-film gas sensors fabricated from such mechanically-alloyed materials were characterized systematically. Very good sensing properties were obtained with a relative resistance value of 82 in 20% oxygen, and at a low operating temperature of 320°C. AC impedance spectra and thermally stimulated current were characterized to investigate the conduction properties of the solid solution, 0.2α-Fe2O3-0.8ZrO2, in air and nitrogen (carrier gas), respectively. It was found that the Arrhenius plots of σT versus 1000/T have two distinct gradients corresponding to two activation energies in the high and low temperature regions. The transition temperature occurs at about 320°C that corresponds to an optimal operating temperature of the gas sensor. It is believed that the high oxygen vacancy concentration present in the solid solution, 0.2α-Fe2O3-0.8ZrO2, and the dissociation of the associated oxygen vacancy defect complexes at 320°C are the critical factors for the high relative resistance to oxygen gas at low operating temperature. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Fluorescence decay characteristic of Tm-doped YAG crystal fiber for sensor applications, investigated from room temperature to 1400°C

    Page(s): 507 - 512
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (311 KB) |  | HTML iconHTML  

    An yttrium aluminum garnet (YAG) crystal fiber with a thulium-doped end tip was specially grown by means of the laser heated pedestal growth approach and designed to be incorporated in a fiber-optic temperature probe. The fluorescence decay characteristics of the crystal fiber, including the temperature dependence of both the fluorescence lifetime and intensity, were comprehensively investigated. Experimental results indicated that the crystal fiber showed a monotonic relationship between the fluorescence lifetime and temperature with an average lifetime sensitivity of 3 μs °C over a wide temperature range, taking measurement from room temperature to 1200°C. Good stability (up to 1400°C) was observed with high repeatability of the fluorescence lifetime during the annealing process carried out on the fiber over this temperature range. The fiber was found to be an excellent candidate material to be used as a fluorescence decay-based fiber thermometer probe and the results are presented on its performance. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Reduced response times using adsorption kinetics and pulsed-mode operation for the detection of oxides of nitrogen with nanocrystalline SnO2 sensors

    Page(s): 447 - 453
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (356 KB) |  | HTML iconHTML  

    The work presented in this paper investigates the use of pulsed temperature operation of nanocrystalline SnO2 sensors for detecting oxides of nitrogen. Pulsed-mode operation was employed to expand the detection range of these sensors while maintaining high sensitivity at low concentrations. In an attempt to reduce the response times of these devices, adsorption kinetics were applied to the response data. Gas concentrations as low as 10 ppb could be rapidly determined without waiting for a steady-state response to be achieved. The sensors also showed a strong response to ppb levels of NO even at low pulsing temperatures. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Nonresonant micromachined gyroscopes with structural mode-decoupling

    Page(s): 497 - 506
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (919 KB) |  | HTML iconHTML  

    This paper reports a novel four-degrees-of-freedom (DOF) nonresonant micromachined gyroscope design concept that addresses two major MEMS gyroscope design challenges: eliminating the mode-matching requirement and minimizing instability and drift due to mechanical coupling between the drive and sense modes. The proposed approach is based on utilizing dynamical amplification both in the 2-DOF drive-direction oscillator and the 2-DOF sense-direction oscillator, which are structurally decoupled, to achieve large oscillation amplitudes without resonance. The overall 4-DOF dynamical system is composed of three proof masses, where second and third masses form the 2-DOF sense-direction oscillator, and the first mass and the combination of the second and third masses form the 2-DOF drive-direction oscillator. The frequency responses of the drive and sense direction oscillators have two resonant peaks and a flat region between the peaks. The device is nominally operated in the flat regions of the response curves belonging to the drive and sense direction oscillators, where the gain is less sensitive to frequency fluctuations. This is achieved by designing the drive and sense anti-resonance frequencies to match. Consequently, by utilizing dynamical amplification in the decoupled 2-DOF oscillators, increased bandwidth and reduced sensitivity to structural and thermal parameter fluctuations and damping changes are achieved, leading to improved robustness and long-term stability over the operating time of the device. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.

Aims & Scope

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

Full Aims & Scope

Meet Our Editors

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