Finite Element Analysis of the Distribution Parameters of a Metal Dot Array in a SAW Gyroscope

Abstract

A surface acoustic wave (SAW) gyroscope has many unique advantages, but a low detection sensitivity limits its development. Previous studies have shown that adding a metal dot array to the acoustic wave propagation path of the SAW delay line can enhance the Coriolis force and further improve sensitivity. Therefore, in order to optimize the detection sensitivity performance of the sensor, 128°YX-LiNbO3, ST-X Quartz and X112°Y-LiTaO3 piezoelectric substrates were selected by finite element method to analyze the influence of the metal dot array size on the SAW gyroscopic effect in this paper. The most suitable metal dot size for 128°YX-LiNbO3 and X112°Y-LiTaO3 obtained by simulation are 5/16λ and 1/16λ, respectively; for example, when the normalized angular velocity is 1 × 10−3, the SAW gyroscopic effect factor g of the two piezoelectric substrates distributing the optimum size metal dots can reach 22.4 kHz and 5.2 kHz. For ST-X quartz, there is a threshold between the rotation speed of the substrate and the optimum size of the metal dot. When the rotating speed is lower than the threshold, the SAW gyroscopic effect is strongest when the metal dot size is 3/16λ; otherwise, the SAW gyroscopic effect is strongest when the size is 11/16λ. These research results provide new ideas for improvement of the SAW gyroscope.

Research on the SAW Gyroscopic Effect in a Double-Layer Substrate Structure Incorporating Non-Piezoelectric Materials

“…Since the reflectivity of SiO 2 is greater than that of STX quartz, it can be concluded that if the reflection coefficient of the lower-layer material is greater than that of the upper-layer material, the energy propagated into the substrate will be more significantly reflected back into the upper layer, causing interference with the Rayleigh wave propagating on the substrate surface and weakening the SAW gyroscopic effect. In our previous research, we found that different substrate structures have different requirements in terms of the optimal size of the metal dot array [26]. Moreover, during the simulation, we observed another phenomenon, whereby the addition of non-piezoelectric materials below the piezoelectric material could also change the optimal size of the metal dot array.…”

“…Additionally, the non-piezoelectric layer was set to 2λ, and a Perfectly Matched Layer (PML) with a thickness of 1λ was set at the bottom to absorb SAW and prevent reflection from affecting the simulation results [40]. Although the distribution of metal dot arrays along the acoustic wave propagation path has been shown to effectively enhance the Coriolis force [25,41], in SAW angular velocity sensors, the size of the metal dot array in terms of length, width, and thickness changes the proportions of the elastic wave energy in the metal dot array, as roughly shown in Figure 3, and the optimal size of the metal dot array varies with the material [26]. Previous research has shown that with increased thickness of the metal dot array, the SAW gyroscopic effect becomes stronger [21], but in this study, we chose a metal dot thickness of 0.9 um due to technological limitations.…”

“…This has been discussed in detail in refs. [24][25][26]. In this paper, we primarily explore methods for increasing the SAW gyroscopic effect, thereby enhancing the sensitivity of sensor detection by means of optimal substrate selection and design.…”