A study of Love wave acoustic sensors in ZnO/quartz structure

Love wave acoustic devices are very suitable as biosensors in liquid environments because of their high sensitivity. Up to now, few systems have been tried to use ZnO film as the guiding layer in the Love wave device. An experimental study of Love-wave devices based on ZnO/ST-cut quartz with different thickness of ZnO films is presented. ZnO films with c-axis orientated crystalline structure have been grown successfully on quartz by r.f. sputtering technique. Phase velocity, sensitivity and temperature coefficient of frequency of Love wave devices have been studied as a function of layer thickness. The maximum sensitivity is obtained as ZnO film is 1.8 μm, near zero temperature coefficient of frequency value (TCF) is obtained as ZnO film is 2.6 μm for a wavelength of 40 μm, separately. The change of insertion loss by Love wave sensor due to the viscosity variation of sensing liquid has been investigated. In this research, we report ZnO/quartz structure of Love wave sensors with high sensitivity and excellent temperature coefficient of the frequency in liquid environment.