A theoretical study of acoustic plate modes as biosensing elements

Shear horizontal acoustic plate model (SH-APM) devices have recently been used as sensing elements, both in biosensor applications and for the physical measurement of fluid properties. Properly designed APM sensors are more sensitive than quartz crystal microbalance (QCM) sensors and suffer much lower attenuation under fluid loading than surface acoustic wave (SAW) sensors. The theory of APMs in a fluid-loaded plate is discussed, and the perturbation of the APMs due to a thin film at the solid-fluid boundary which, in the case of a biosensor, may arise from antibody-antigen reactions or DNA hybridization is described. Typical results are presented for ZX LiNbO/sub 3/ and ST-X quartz and are compared with experimental results.<
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