Abstract
Acoustic-wave-based voltage sensors utilizing surface acoustic wave (SAW) delay lines are reviewed. A SAW oscillator that consists of a SAW delay line and an amplifier connected between input and output interdigital transducers (IDTs) can be used as a SAW-based voltage sensor, when a d.c. or a.c. voltage is applied on the SAW propagation path in the piezoelectric substrate. The voltage sensors detect an applied voltage as a fractional change of oscillation frequency. there are two electrode configurations for applying a voltage to the substrates on which the SAW propagates. One is to apply a voltage perpendicular to the surface of the substrate, and the other is to apply it parallel to the surface of the substrate and perpendicular to the propagation direction of the SAW. The former configuration is used in a sensor having a ZnO thin film on Si and a sensor utilizing a Lamb wave, as well as in a sensor utilizing a Rayleigh wave on LiNbO 3 plates, whereas the latter is used in a sensor with SAW waveguides.
Published Version
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