Optimizing crystal cut and the frequency shift of a langasite surface acoustic pressure sensor with new FEM approach

Abstract

Pressure monitoring in a high-temperature condition stands as a primary objective in development and optimization of pressure sensors. Langasite, which are known to be useful in high temperatures, is a great candidate for gauging pressure in such challenging environments, particularly in Surface Acoustic Wave (SAW) devices. Employing a new FEM approach, we provide calculating the frequency shift of the resonator when subjected to varying force angles. Our analysis extends to consider nonlinear material constants, including second and third-order piezoelectric, electrostrictive, and thirdorder dielectric constants. Within this study, we computed the sensitivity of stress-induced velocity shifts, incorporating the effects of nonlinear parameters. Validation of our numerical findings is conducted against experimental data obtained from a SAW quartz circular resonator, where the force application rotates around the SAW disk at specific angles relative to the wave propagation direction. Presenting the results concluded from our findings, we present a comprehensive forcevelocity effect graph, describing the interplay between force angle rotation and frequency shift across various Euler angles. Our numerical results are consistent with experimental measurements, demonstrating alignment both in overall trends and the span of frequency shifts observed. The validation process agrees with our numerical approach, as evidenced by its applicability to diverse configurations of SAW resonators with varying Euler angle arrangements. Notably, our analysis reveals that Y-cut Langasite (LGS) SAW resonators exhibit lower sensitivity to force-velocity effects compared to their Y-cut quartz SAW sensor counterparts.