The SAW Resonators on LiNbO3 for Mass-Sensing Applications

A mass-loading effect SAW resonator with shorted synchronously reflectors is presented in this work. The input and output Interdigital Transducer (IDT) has 10 pairs of aluminum electrodes on the high K-2 LiNbO3 Substrate. The acoustic waves generated from input IDT travel to output IDT and convert into electric signals. The sensing area includes of the input, output IDTs and reflectors. The velocity and frequency of acoustic waves change when the mass is on the sensing area. The mass on the electrodes causes the mass-loading effects and decreases the center frequency. The sensitivity curve can be obtained due to the center frequency shift. In this work, the Potassium Chloride (KCL) is used to deposit on the sensing area. Different concentrations of KCL solution lead to different masses and center frequencies on the surface. According to the simulation results, it shows the linearity between the center frequency shift and the thickness of the deposited KCL layer.