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

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.