Theoretical study and finite element simulation of ZnO/GaAs higher-order Lamb waves for microsensor application in liquid media

Abstract: Lamb waves with dominantly longitudinal displacement component have been reported for sensor application in liquid media. However, they are still limited for the fundamental symmetry mode with low plate thickness-to-wavelength (h/l) ratio, resulting in large wavelength and low resonance frequency. Here we show the finite element simulation study of higher-order Lamb waves on GaAs and ZnO/GaAs plates. In-plane polarised quasi-longitudinal higher-order Lamb waves are obtained at higher h/l ratio resulting in higher resonance frequencies. The solid-liquid contact simulation shows the confinement of acoustic energy inside the plate. The result demonstrates the suitability of ZnO/GaAs higher-order quasi-longitudinal modes for microsensor in liquid media.