A shear horizontal-mode surface acoustic wave (SH-SAW) has the unique characteristic of complete reflection at a free edge normal to the direction of propagation, making it possible to construct a reflective delay line. A passive SAW strain sensor based on such a reflective delay line is presented. The reflective delay line is constructed on a 36° YX LiTaO 3 substrate. The SH-SAW velocity is shown to provide a reliable measure of the strain of a propagation surface, and incorporation of an oscillator circuit is demonstrated to allow wireless remote monitoring of strain using this sensor.
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