Comparison of different operational modes on LiTaO3 LFE bulk acoustic wave sensors

Abstract

Previous studies have shown that when working in liquid, (yxl)90° LiTaO3 LFE devices work on pure-LFE mode (the observed bulk acoustic wave is excited by the lateral field) and (yxl)0° LiTaO3 LFE devices work on pseudo-LFE mode (the observed bulk acoustic wave is not excited by the lateral field but the thickness field with the liquid acting as an virtual electrode). In this work, LiTaO3 LFE devices on both modes are designed and fabricated. The devices' sensitivities to liquid conductivity and permittivity were tested and compared. The experimental results showed that compared to the LiTaO3 pure-LFE device, the LiTaO3 pseudo-LFE device has much higher sensitivities to liquid electrical property changes.