An investigation of the dependence of ZnO film on the sensitivity of Love mode sensor in ZnO/quartz structure

Abstract

Love mode acoustic devices are very promising as biosensors in liquid environments because of their high sensitivity. An experimental study of Love mode sensors based on ZnO/90° rotated ST-cut quartz structure with different sputtering conditions to deposit ZnO films is presented. In order to achieve sensor with higher sensitivity, the effects of sputtering substrate temperatures to deposit ZnO films on the sensitivity of viscosity and conductivity were investigated. Phase velocity, sensitivity and temperature coefficient of frequency (TCF) of Love wave devices have been studied. The Love wave sensor has higher sensitivity as sputtering ZnO films on the unheated substrate than that of on the heated substrate. The maximum sensitivity up to −18.77×10 −8 m 2 s kg −1 of ZnO film with thickness of 1.8 μm for a wavelength of 40 μm is much bigger than SiO 2/quartz structure. In this research, we report ZnO/90° rotated ST-cut quartz structure of Love wave sensors with high sensitivity of viscosity and conductivity in liquid circumstance and TCF of quartz is compensated by ZnO film.