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Ultrasonics, Ferroelectrics, and Frequency Control, IEEE Transactions on

Issue 5 • Date Sept. 1998

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Displaying Results 1 - 25 of 39
  • Comments on the effects of nonuniform mass loading on a quartz crystal microbalance

    Publication Year: 1998 , Page(s): 1123 - 1124
    Cited by:  Papers (9)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (155 KB)  

    The Sauerbrey equation can yield incorrect results when the mass and amplitude of vibration distributions are not uniform, and when the mass is not attached rigidly. View full abstract»

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  • Gas sensing properties of Langmuir-Blodgett polypyrrole film investigated by surface acoustic waves

    Publication Year: 1998 , Page(s): 1125 - 1132
    Cited by:  Papers (6)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (852 KB)  

    The gas sensing properties of organic polypyrrole (PPS) film, deposited onto LiNbO/sub 3/ substrate by Langmuir-Blodgett (LB) technique, have been monitored by surface acoustic wave (SAW) delay lines and studied with respect to sensitivity, selectivity, response time, stability, repeatability, and aging. The SAW PPy elements demonstrate high sensitivity toward NH/sub 3/ gas with high selectivity against CH/sub 4/, CO, H/sub 2/, and O/sub 2/. The detectable threshold concentration has been estimated as 20 ppm NH/sub 3/ in air; the response time is in the 10s range, and the recovery time is about 15 min; the repeatability of the SAW response toward eight sequential NH/sub 3/ gas exposures is within 6%; the aging of the PPy film is within 4% over a month; and the effect of humidity on SAW NH/sub 3/ gas response is negligible for the typical conditions at room ambient air. Partially reversible SAW response recognizing NH/sub 3/ gas as one component of an interfering gases-mixture has been observed. Simultaneous chemoresponses of SAW phase and insertion loss have been performed in order to investigate the sensing mechanisms. By merging with electrical conductivity gas response, the dominant SAW sensing effects for NH/sub 3/ gas detection are defined as elastic loading. View full abstract»

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  • Standing wave bi-directional linearly moving ultrasonic motor

    Publication Year: 1998 , Page(s): 1133 - 1139
    Cited by:  Papers (16)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (851 KB)  

    A standing wave bi-directional linearly moving ultrasonic motor has been studied for the purpose of implementing a practical linear ultrasonic motor with simple structure, simple driving and high resolution. The fundamental principle of this linear motor is projections on the right sides of a standing wave crests generating thrust force right-diagonally on the slider pressed against the projections. Correspondingly, projections on the left sides of the wave crests make the slider move toward the left. In order to realize bi-directional actuating, vibration mode B3 or B4 is excited in a rectangular plate-type vibrator to make the projections on the right sides or the left sides of the wave crests. In this paper, the operation principle of the linear motor is demonstrated. Furthermore, a prototype linear ultrasonic motor of 40 mm in length, 10 mm in width is fabricated and investigated. The following performances have been achieved: maximum speed 200 mm/s, maximum force output 150 gf, and resolution less than 0.1 /spl mu/m. View full abstract»

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  • Inductively coupled surface acoustic wave device for sensor application

    Publication Year: 1998 , Page(s): 1140 - 1144
    Cited by:  Papers (1)  |  Patents (2)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (630 KB)  

    We present a new type of surface acoustic wave device for sensor applications where the need for bonding wires is eliminated. Instead the device is coupled inductively to the RF circuitry. The impedance of such devices and the necessary matching have been investigated both theoretically and experimentally. The devices have repeatedly been operated at temperatures up to 400/spl deg/C and have shown a good temperature resistance. In order to test the suitability of the new concept for sensor applications, several devices with an operating frequency of 363 MHz were coated with copper phthalocyanine for the detection of NO/sub 2/. From these measurements we derive a detection limit of these devices below 1 ppb for NO/sub 2/. View full abstract»

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  • A planar unimorph-based actuator with large vertical displacement capability. I. Experiment

    Publication Year: 1998 , Page(s): 1145 - 1150
    Cited by:  Papers (3)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (829 KB)  

    A piezoelectric actuator utilizing a planar arrangement of unimorph elements that produces displacements perpendicular to the plane of the actuator is described. The elements are connected in series mechanically so that the vertical displacement of each element adds to the vertical displacements of the other elements. Two prototype actuators were built and tested. One was stick-built from individual bars of PZT and aluminum, which were epoxied together and connected to each other with short aluminum connector bars. The other was fabricated monolithically from a single plate of PZT by bead-blasting the PZT plate through a steel shadowmask to mill out the desired actuator shape. Copper bars epoxied to the milled-out PZT bars then formed the unimorph elements. The unloaded output displacement of each actuator versus applied voltage was measured as well as the displacement versus applied force with no applied voltage. These measurements were in agreement with the predictions of an electromechanical model of the actuator that has been developed. The model predicted and measurements verified that stiffeners can be added to the basic geometry that will significantly increase the force output without affecting the displacement versus applied voltage characteristic. View full abstract»

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  • A planar unimorph-based actuator with large vertical displacement capability. II. Theory

    Publication Year: 1998 , Page(s): 1151 - 1160
    Cited by:  Papers (3)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1028 KB)  

    A piezoelectric actuator utilizing a planar trellis-like arrangement of multiple unimorph elements is described which produces displacements perpendicular to the plane of the actuator. The unimorph elements are connected in series mechanically so that the vertical displacement of each unimorph element in the structure adds to the vertical displacements of the other elements, resulting in a large overall vertical displacement at the output of the actuator. A simple electromechanical model of the actuator is developed. The model consists of a voltage-actuated force source, which is the result of the piezoelectric properties of the unimorph bars that make up the actuator, in parallel mechanically with a stiff spring that models the elastic response, both bending and twisting, of the unimorph elements. The long moment arms inherent in the geometry of the actuator make a substantial contribution to the overall compliance of the actuator. The addition of stiffeners to the actuator can significantly reduce the effect of these moment arms, and thus substantially increase the stiffness of the actuator. As a result, the force generation capability of the actuator is significantly increased without affecting its displacement capability. View full abstract»

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  • Wireless sensing using oscillator circuits locked to remote high-Q SAW resonators

    Publication Year: 1998 , Page(s): 1161 - 1168
    Cited by:  Papers (29)  |  Patents (4)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (981 KB)  

    This paper introduces a method of wireless read out of high Q surface acoustic wave (SAW) resonator sensors. The resonator is excited by a short RF pulse and decays after switching off the interrogating signal. In the measurement system, a gated phase locked loop (GPLL) locks to the resonance frequency of the SAW resonator within a few bursts. Then the frequency of the GPLL oscillator is synchronized to the resonance of the sensor and can be measured easily. The concept is intended to yield an alternative to interrogators with expensive signal processing. Considering the inherent limitations, the proposed system presents a low cost solution for temperature, force, torque, etc. measurements. We describe the sensors, the signals, and the implemented system. Results of temperature measurements using quartz resonators are presented, and merits and disadvantages are discussed. View full abstract»

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  • PZT thin film actuated elastic fin micromotor

    Publication Year: 1998 , Page(s): 1169 - 1177
    Cited by:  Papers (12)  |  Patents (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1194 KB)  

    A piezoelectric elastic fin micromotor based on a PbZr/sub 0.53/Ti/sub 0.47/O/sub 3/ thin film driving a micromachined silicon membrane was fabricated and studied. The stator was characterized by interferometry, and a laser set-up was used to measure the angular velocity and acceleration of the motor. The torque, the output power, and the efficiency of the device were extracted from these measurements. Values up to 1020 rpm and 0.94 /spl mu/Nm were observed for the velocity and the torque, respectively, which would be sufficient for a wristwatch application. The present version exhibited an efficiency of 0.17%, which could theoretically be increased to 4.8%. View full abstract»

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  • A cylindrical micro ultrasonic motor using PZT thin film deposited by single process hydrothermal method (/spl phi/2.4 mm, L=10 mm stator transducer)

    Publication Year: 1998 , Page(s): 1178 - 1187
    Cited by:  Papers (15)  |  Patents (4)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1575 KB)  

    A micro ultrasonic motor using PZT (lead zirconate titanate) thin film has been improved by a single process hydrothermal method. The hydrothermal method is a unique method for depositing PZT thin film in a solution. An earlier reported hydrothermal method consisted of two linked processes. Our new method, however, has only a single process. Hence, less distribution of chemical components of the PZT film contributes to a higher efficiency of the stator transducer. The piezoelectric factor d/sub 31/ was -30 pC/N for this new method, which is six times larger than that of the previous method. The output torque of the micro ultrasonic motor fabricated by the single process hydrothermal method was measured. The output torque was 7.0 /spl mu/Nm, and the maximum revolution speed was 880 rpm at 15 Vp-p driving voltage. View full abstract»

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  • Transducer for high speed and large thrust ultrasonic linear motor using two sandwich-type vibrators

    Publication Year: 1998 , Page(s): 1188 - 1195
    Cited by:  Papers (18)  |  Patents (3)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1277 KB)  

    A transducer for an ultrasonic motor using two sandwich-type vibrators has been proposed and designed. The vibrators cross at right angles with each other at the tip. The transducer has two vibration modes; one is a symmetrical mode and the other is anti-symmetric. The normal direction motion of the transducer tip is excited by the symmetrical mode. The lateral motion of the tip is excited by the anti-symmetrical mode. The transducer is designed so that these vibration modes are degenerated. To obtain high output force and high power, materials were carefully selected. Heat-treated high strength chromium manganese steel bolts were used for binding the PZT elements. A zirconia ceramics plate was bonded on the transducer tip as frictional material. The no-load maximum speed was 3.5 m/sec. The output force was 39 N at the driving voltage of 500 V/sub rms/ and the preload of 150 N. At this condition the maximum efficiency was 28%, and the velocity was 0.55 m/sec. The maximum output force was 51 N, which was 17 times of the transducer weight. The maximum output power per unit weight was 76 W/kg. View full abstract»

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  • Quartz thickness-shear mode pressure sensor design for enhanced sensitivity

    Publication Year: 1998 , Page(s): 1196 - 1203
    Cited by:  Papers (17)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1205 KB)  

    Companies in the oil and gas industry rely upon acquisition of accurate downhole pressure data for management of reservoir resources. Pressure data must be acquired in extreme environments present in wells, including high pressures, high temperatures, and high levels of shock and vibration. A primary concern of oil and gas companies is that pressure transducers provide reliable data throughout the duration of well-testing jobs. Important performance parameters for well-test pressure gauges include inaccuracy arising from nonlinearity, hysteresis, nonrepeatability, and temperature. Accurate pressure measurements are required for determination of reservoir resources. Sensor output per unit pressure (sensitivity) and the corresponding minimum resolvable pressure (resolution) are important performance considerations. Pressure resolution is the key parameter for dynamic well-test analyses used to determine reservoir properties. Design limits, including maximum allowable pressure over the operating temperature range, also must be known. Pressure transducers must retain acceptable performance characteristics including accuracy, sensitivity, and resolution for long periods of operation to provide reliable data and reduce the frequency and cost of recalibration. This paper describes a unique quartz thickness-shear mode sensor that was developed for downhole pressure measurements. Pressure transducers that use this sensor meet the demanding requirements of downhole testing. View full abstract»

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  • Mass effects of quartz resonant sensors with different surface microstructures in liquids

    Publication Year: 1998 , Page(s): 1204 - 1210
    Cited by:  Papers (3)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1352 KB)  

    Liquid trapped by the rough surface of a quartz resonator vibrating in thickness-shear mode (TSM) will act as a mass effect to the crystal. It has been proven that this mass effect not only depends on the liquid mass enclosed in the surface cavities, but also the liquid properties and the crystal surface features. Based on a series of experiments, this paper introduces "trapping factor" to analyze the mechanism of the liquid mass effect. Influences of different surface microstructures, including structure dimension and orientation, on the liquid mass effect have been studied on 10 MHz fundamental mode AT-cut resonators. The result indicates that the trapping factor of a chess-board structure has no advantage compared to a line-structure. For the same structure height of 0.4 /spl mu/m, the mass effect of a crystal with about 3 /spl mu/m distance line-structure is bigger than that of a 7.5 /spl mu/m distance line-structure. With a similar surface roughness value (R/sub a/), the crystal with a line structured surface has a much bigger mass effect than that with a randomly rough surface. View full abstract»

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  • Modification of piezoelectric vibratory gyroscope resonator parameters by feedback control

    Publication Year: 1998 , Page(s): 1211 - 1215
    Cited by:  Papers (10)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (610 KB)  

    A method for analyzing the effect of feedback control on the dynamics of piezoelectric resonators used in vibratory gyroscopes has been developed. This method can be used to determine the feasibility of replacing the traditional mechanical balancing operations, used to adjust the resonant frequency, by displacement feedback and for determining the velocity feedback required to produce a particular bandwidth. Experiments were performed on a cylindrical resonator with discrete piezoelectric actuation and sensing elements to demonstrate the principles. Good agreement between analysis and experiment was obtained, and it was shown that this type of resonator could be balanced by displacement feedback. The analysis method presented also is applicable to micromachined piezoelectric gyroscopes. View full abstract»

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  • A concentration dependent study of acoustic plate mode immunosensor response using antigen/antibody systems with different binding ability

    Publication Year: 1998 , Page(s): 1216 - 1220
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (587 KB)  

    Acoustic plate mode sensors have been used to monitor immunochemical reactions as a function of antigen concentration. In the studies, antibodies were covalently linked to the gold-coated sensing surface via mercaptoethanol, aminosilane, and glutaraldehyde. Two antigen/antibody model systems that differ in their ability to mutually bind one another have been used. For sensor operation at about 150 MHz, a detection limit of approximately 0.5 /spl mu/g/ml was obtained in both cases. No significant difference between the two systems was found for the value of the binding constants. They amount to about 1/spl middot/10/sup 8/ 1/mole and fall well into the range of binding constants reported for homogeneous immunoassays. A comparison of the sensor response obtained for the two model systems shows that about 70% of the immobilized antibodies are active. View full abstract»

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  • Reciprocity calibration of impulse responses of acoustic emission transducers

    Publication Year: 1998 , Page(s): 1221 - 1228
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (887 KB)  

    By means of reciprocity calibration in Rayleigh-wave and longitudinal-wave sound fields, frequency characteristics of amplitude and phase of absolute sensitivity of acoustic emission transducers were measured on the basis of the newly derived complex reciprocity parameters, and the impulse responses were obtained through inverse Fourier transform. Calibration results were confirmed with supplemental experiments in which the fracturing of a pencil lead was utilized for the source of elastic waves. Impulse responses of acoustic emission transducers to both the Rayleigh-wave and longitudinal-wave displacement velocities were determined by means of purely electrical measurements without the use of mechanical sound sources or reference transducers. View full abstract»

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  • Elastic contact conditions to optimize friction drive of surface acoustic wave motor

    Publication Year: 1998 , Page(s): 1229 - 1237
    Cited by:  Papers (10)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1085 KB)  

    The optimum pressing force, namely the preload, for a slider to obtain superior operation conditions in a surface acoustic wave motor have been examined. We used steel balls as sliders. The preload was controlled using a permanent magnet. The steel balls were 0.5, 1, and 2 mm diameter, with the differences in diameter making it possible to change contact conditions, such as the contact pressure, contact area, and deformation of the stator and the slider. The stator transducer was lithium niobate, 128 degrees rotated, y-cut x-propagation substrate. The driving frequency of the Rayleigh wave was about 10 MHz. Hence, the particle vibration amplitude at the surface is as small as 10 nm. For superior friction drive conditions, a high contact pressure was required. For example, in the case of the 1 mm diameter steel ball at the sinusoidal driving voltage of 180 V/sub peak/, the slider speed was 43 cm/sec, the thrust output force was 1 mN, and the acceleration was 23 times as large as the gravitational acceleration at a contact pressure of 390 MPa. From the Hertz theory of contact stress, the contact area radius was only 3 /spl mu/m. The estimation of the friction drive performance was carried out from the transient traveling distance of the slider in a 3 msec burst drive. As a result, the deformation of the stator and the slider by the preload should be half of the vibration amplitude. This condition was independent of the ball diameter and the vibration amplitude. The output thrust per square millimeter was 50 N, and the maximum speed was 0.7 m/sec. From these results, we conclude that it is possible for the surface acoustic wave motor to have a large output force, high speed, quick response, long traveling distance, and a thin micro linear actuator. View full abstract»

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  • A temperature insensitive quartz microbalance

    Publication Year: 1998 , Page(s): 1238 - 1245
    Cited by:  Papers (8)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (996 KB)  

    Mass deposition onto a microbalance is generally accompanied by a temperature change. By measuring a single frequency only, it is not possible to separate the frequency change due to mass change from that due to temperature change. In the temperature insensitive microbalance technique, measurements of two frequencies, the fundamental mode and third overtone frequencies of an SC-cut resonator, yield two equations with two unknowns. This allows the separation of mass change effects from temperature change effects. Dual mode excitation can be used for highly accurate resonator self-temperature sensing over wide temperature ranges. SC-cut resonators are also thermal transient compensated. These unique properties allowed the development of a temperature compensated microbalance that is highly sensitive to mass changes, which can be used in rapidly changing thermal environments, over wide temperature ranges, and which requires neither temperature control nor a thermometer other than the resonator. To demonstrate the performance of this microbalance, SC-cut resonators were coated with thin polymethylmethacrylate (PMMA) photoresist films then placed into a UV-ozone cleaning chamber that initially was at about 20/spl deg/C. When the UV lamp was turned on, the UV-ozone removed PMMA from the surfaces while the chamber temperature rose to about 60/spl deg/C. The frequency changes due to mass changes could be accurately determined, independently of the frequency changes due to temperature changes. View full abstract»

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  • Frequency response of multilayer pyroelectric sensors

    Publication Year: 1998 , Page(s): 1246 - 1254
    Cited by:  Papers (3)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1014 KB)  

    The pyroelectric response of the multilayer system consisting of the front surroundings, the pyroelectric element, the intermediate layer, and the back surroundings is calculated. The general expression and simple relations are obtained between main geometric and thermophysical parameters of the system under consideration and characteristics of the pyroelectric response in a large variety of configurations of pyroelectric sensors, such as detectors with the pyroelectric element in a gas, detectors without air gap as well as detectors with air gap between the element and the substrate, and detectors in immersion systems, etc. In particular, it is shown that, for the detectors with air gap, the wide flat part of the frequency response appears with any properties of substrate if the double thermal resistance of the air gap exceed that of the pyroelectric element, whereas for the detectors without air gap it appears only if the substrate has relatively large complex thermal conductivity. View full abstract»

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  • Low-frequency response of pyroelectric sensors

    Publication Year: 1998 , Page(s): 1255 - 1260
    Cited by:  Papers (2)  |  Patents (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (753 KB)  

    Sensitivity of pyroelectric IR-detectors of slow thermal processes, especially of human body sensors, depends strongly on their response in the infra-low (/spl sim/0.1 to 1 Hz) region of frequency spectrum. The main mechanisms of heat losses-heat conduction of environment, lateral heat conduction in the plane of sensitive element, and emission of radiation-are considered. Their influence on the low-frequency response of pyroelectric sensors is estimated. Exact solutions and simple expressions for quantitative description of main specific features of real systems are obtained. Criteria of validity of the adequate models are determined. View full abstract»

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  • Chemical sensor based on surface acoustic wave resonator using Langmuir-Blodgett film

    Publication Year: 1998 , Page(s): 1261 - 1265
    Cited by:  Papers (5)  |  Patents (2)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (505 KB)  

    A one-port surface acoustic wave (SAW) resonators incorporating Langmuir-Blodgett (LB) films has been investigated. SAW sensors are one potential applications of SAW devices. Most of the work reported on SAW sensor concerns delay lines. In this paper we characterize the mass loading effects of one-port resonators by depositing successive monolayers of LB films onto the surface. A 90 MHz SAW gas-phase sensor has been fabricated on an ST cut quartz substrate, and one-port resonator configurations have been used as the sensing element. Ultra thin monolayers of arachidic acid and arachidic acid ethyl ester have been deposited using the LB method. The resonant frequencies and the Q values have been measured as sensor response. Experimental results show that the Q values and the resonant frequencies of the one-port SAW resonator vary with film mass loading on the SAW device surface. View full abstract»

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  • Mass sensitivity of acoustic plate mode in liquids

    Publication Year: 1998 , Page(s): 1266 - 1272
    Cited by:  Papers (8)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (831 KB)  

    In this paper, the concept of electrical effective permittivity function is used to calculate the eigen-frequencies and the particle displacements of piezoelectric acoustic plate modes (APM). These results allowed us to determine the mass sensitivities of the first order vibration modes using a first order perturbation theory. Theoretical results are discussed and compared to those of a variational method and isotropic two-layer composite analysis in the case of a shear horizontal APM sensor on a singly rotated cut quartz substrate. Experimental measurements by a copper electrodeposition are carried out and show that the perturbation method leads to a better understanding of the APM behavior. View full abstract»

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  • Surface acoustic wave thermogravimetric measurements of thin polymer films

    Publication Year: 1998 , Page(s): 1273 - 1280
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1097 KB)  

    The increased use of thin film polymers in microelectronic applications has resulted in the need to better understand their chemical, thermal, mechanical, and electrical properties. Of particular interest are changes in mass and viscoelasticity during curing of new high temperature polymers. A highly sensitive technique that can monitor mass and viscoelastic changes in thin polymer films during curing to high temperature is needed. In this work a surface acoustic wave (SAW) based system was developed that was capable of measuring the mass loss due to water outgassing during cure of thin polymer films in a temperature range of 20 to 400/spl deg/C. It also could measure the apparent glass transition temperature of acoustically thin films, and film resonance for acoustically thick films. The principle limitations of the system are the limited accuracy of temperature compensation and the limited ability to separate mass loss effects from viscoelastic effects. View full abstract»

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  • Theory and application of passive SAW radio transponders as sensors

    Publication Year: 1998 , Page(s): 1281 - 1292
    Cited by:  Papers (84)  |  Patents (15)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1616 KB)  

    Surface acoustic wave (SAW) radio transponders make it possible to read identification codes or measurement values from a remote location. The decisive advantage of these SAW transponders lies in their passive operation (i.e., no power-supply), and in the possibility of wireless installation at particularly inaccessible locations. The passive SAW transponders are maintenance free. Identification marks respond to an interrogation signal with their nonchanging identification pattern. In wireless SAW sensors the physical or chemical properties to be detected change the propagation characteristics of the SAW. SAW radio transponders are advantageously placed on moving or rotating parts and in hazardous environments such as contaminated or high voltage areas. They also can be used for contactless measurements in high vacuum process chambers, under concrete, extreme heat, or strong radioactive radiation, where the use of conventional sensors is complicated, dangerous, or expensive. In this paper we discuss the principles of wireless passive SAW transponders and present a radio frequency interrogation unit and several passive radio SAW sensors developed for noncontact measurements of temperatures, pressures, torques, and currents. View full abstract»

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  • Analysis and optimization of Love wave liquid sensors

    Publication Year: 1998 , Page(s): 1293 - 1302
    Cited by:  Papers (13)  |  Patents (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1252 KB)  

    Love wave sensors are highly sensitive microacoustic devices, which are well suited for liquid sensing applications thanks to the shear polarization of the wave. The sensing mechanism thereby relies on the mechanical (or acoustic) interaction of the device with the liquid. The successful utilization of Love wave devices for this purpose requires proper shielding to avoid unwanted electric interaction of the liquid with the wave and the transducers. In this work we describe the effects of this electric interaction and the proper design of a shield to prevent it. We present analysis methods, which illustrate the impact of the interaction and which help to obtain an optimized design of the proposed shield. We also present experimental results for devices that have been fabricated according to these design rules. View full abstract»

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  • Sensitivity and optimization of a high-Q sapphire dielectric motion-sensing transducer

    Publication Year: 1998 , Page(s): 1303 - 1313
    Cited by:  Papers (2)  |  Patents (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1342 KB)  

    A high-Q sapphire dielectric motion sensing transducer that operates at microwave frequencies has been developed. The device uses cylindrical whispering gallery modes of quality factor greater than 10/sup 5/ at room temperature and greater than 10/sup 8/ at 4 K. The tuning coefficient of the transducer resonance frequency with respect to displacement was measured to be of the order of a few MHz//spl mu/m. An electromagnetic model that predicts the resonant frequency and tuning coefficient has been developed and was verified by experiment. We implemented the model to determine what aspect ratio and what dielectric mode is necessary to maximize the sensitivity. We found that the optimum mode type was a TM whispering gallery mode with azimuthal mode number of about 7 for a resonator of 3 cm in diameter. Also, we determined that the tuning coefficients were maximized by choosing an aspect ratio that has a large diameter with respect to the height. By implementing a microwave pump oscillator of SSB phase noise -125 dBc/Hz at 1 kHz; offset, we have measured a sensitivity of order 10/sup -16/ m//spl radic/Hz. We show that this can be improved with existing technology to 10/sup -18/ m//spl radic/Hz, and that in the near future this may be further improved to 10/sup -19/ m//spl radic/Hz. View full abstract»

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Aims & Scope

IEEE Transactions on Ultrasonics, Ferroelectrics and Frequency Control focuses on the theory, design, and application on generation, transmission, and detection of bulk and surface mechanical waves.

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Editor-in-Chief
Steven Freear
s.freear@leeds.ac.uk