Surface-acoustic-wave oscillators: mode selection and frequency modulation

Crabb, Justin; Lewis, M.F.; Maines, J.D.

doi:10.1049/el:19730144

Cited by 42 publications

(6 citation statements)

References 4 publications

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“…(5) was achieved by careful selection of the coaxial cables length to obtain c that provides an overall phase shift equal to 2 P and to operate the SAW sensor at the resonant frequency which is predetermined by the network analyzer analysis using 50 calibrated leads. This approach was adopted by several groups and a graphic representation of the above described oscillator configuration can be found elsewhere [33,39,40]. A Fluke high-resolution frequency counter (PM66860B) was used to measure the sensor operational frequency upon exposure to target gases.…”

Section: Methodsmentioning

confidence: 99%

Polypyrrole nanofiber surface acoustic wave gas sensors

Al-Mashat

Tran

Włodarski

et al. 2008

Sensors and Actuators B: Chemical

124

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Section: Methodsmentioning

confidence: 99%

Polypyrrole nanofiber surface acoustic wave gas sensors

Al-Mashat

Tran

Włodarski

et al. 2008

Sensors and Actuators B: Chemical

124

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“…SPUDT and combed structure can enhance the generated signal in the forward direction but reduce the signal in the reverse direction using the distributed reflection sources (λ/4 reflection electrode), which suppress triple transit and reduce insertion loss effectively [11]. Single-mode selection can be simply accomplished by a comb transducer which is a means of combination of frequency selectivity of two IDTs to suppress all unwanted frequencies [12]. In order to keep the uniformity of the acoustic velocity, many pseudo fingers are distributed between the teeth of the comb transducer.…”

Section: Design Considerationsmentioning

confidence: 99%

Enhanced sensitivity of a surface acoustic wave gyroscope using a progressive wave

Lee

Yang

et al. 2011

J. Micromech. Microeng.

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A surface acoustic wave (SAW)-based gyroscope with an 80 MHz central frequency was developed on two different piezoelectric substrates (128° YX LiNbO3 and ST-X quartz). A sensor was developed that contained two SAW oscillators. One oscillator was used as the sensing element and had metallic dots in the cavity between the input and output interdigital transducers (IDTs). The other oscillator was used as a reference element. Two oscillators were formed to extract the Coriolis effect by comparing the oscillation frequencies between these two delay lines, and metallic dots were used to induce a Coriolis force. Three different IDT structures were used to obtain a stable progressive SAW. Coupling of modes modeling was conducted prior to fabrication for determining the optimal device parameters. The device was fabricated and then measured on a rate table in accordance with the results of simulation. When the device was subjected to an angular rotation, the oscillation frequencies of the two oscillators were observed to differ. Depending on the angular velocity, the frequency difference was linearly modulated. The obtained sensitivity was approximately 62.57 Hz deg−1 s−1 at angular rates in the range 0–1000 deg s−1 in the case of the LiNbO3 substrate and single-phase unidirectional transducer and combed electrode structure. The dependence of the device performance on the piezoelectric substrate, IDT structure, and temperatures was also characterized. The developed device has good resistance to mechanical shock and stability to temperature.

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“…This approach, however, may cause mode hopping if the oscillation condition is fulfilled near the side lobes of the transfer function. This can be avoided if CC is chosen in such a way that the poles of the magnitude meet the phase condition for the first side lobe, eg, if the length of the IDT equals CC [16]. However, this configuration is disadvantageous since the phase slope is fairly low and electromagnetic cross talk is likely because of the vicinity of the IDTs.…”

Section: Oscillator Setupmentioning

confidence: 99%

Microacoustic Sensors for Liquid Monitoring

et al. 2001

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In recent years, much effort has been expended to developing miniaturized, reliable sensors for measuring physical and chemical liquid properties. Microacoustic devices may be employed to determinate physical quantities perturbing the propagation conditions of the acoustic wave, even in liquid environments. For liquid sensors, acoustic modes with shear polarization are often used in order to avoid radiation losses. Examples are shear bulk modes, surface skimming bulk waves, shear-horizontal acoustic plate modes, and Love modes. Furthermore, modes with sagittal polarization may be applied if their phase velocity is sufficiently lower than the sound velocity in the adjacent liquid. General interactions between acoustic waves and liquids are viscous coupling, acoustoelectric effects, and mass loading. The resulting changes in device frequency and attenuation may be utilized for sensing purposes.The general advantages of microacoustic sensors are high sensitivity, simple fabrication, and quasidigital frequency readout. Hence, a wide variety of devices based on different modes for very different applications has been discussed in the relevant literature. The aim of this review is to provide a systematic overview of microacoustic sensors particularlay suited for operation in liquids.First, we provide a brief introductionto surfaceacousticwave devices and the underlying physics, basic microacoustic structures, and general measurement techniques. A description of the mechanisms of interaction between liquids and acoustic waves is then followed by a comprehensive survey covering the different types of microacoustic liquid sensors, with emphasis on the mode-specific device properties. Thereafter, aspects of material selection and device fabrication are summarized. Lastly, an overview is given indicating where microacoustic liquid sensors have already been put into practice and where their application may be expected in the near future.

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Surface-acoustic-wave oscillators: mode selection and frequency modulation

Cited by 42 publications

References 4 publications

Polypyrrole nanofiber surface acoustic wave gas sensors

Polypyrrole nanofiber surface acoustic wave gas sensors

Enhanced sensitivity of a surface acoustic wave gyroscope using a progressive wave

Microacoustic Sensors for Liquid Monitoring

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