Optimization of surface acoustic wave-based rate sensors.

Fangqian Xu,Xiuting Shao,Wen Wang,Yong Liang,Xinlu Liu

doi:10.3390/s151025761

Abstract

The optimization of an surface acoustic wave (SAW)-based rate sensor incorporating metallic dot arrays was performed by using the approach of partial-wave analysis in layered media. The optimal sensor chip designs, including the material choice of piezoelectric crystals and metallic dots, dot thickness, and sensor operation frequency were determined theoretically. The theoretical predictions were confirmed experimentally by using the developed SAW sensor composed of differential delay line-oscillators and a metallic dot array deposited along the acoustic wave propagation path of the SAW delay lines. A significant improvement in sensor sensitivity was achieved in the case of 128° YX LiNbO3, and a thicker Au dot array, and low operation frequency were used to structure the sensor.

Highlights

The surface acoustic wave (SAW)-based micro rate sensor has gained increasing attraction for inertial navigation applications because it exhibits many unique properties such as superior inherent shock robustness, a wide dynamic range, low cost, small size, and long working life compared to other current gyroscope types [1]
Sensors 2015, 15 effect [2,3], that is, as the Coriolis force induced by the applied rotation acts on the vibrating particles along the SAW propagation path, a pseudo running wave shifted by a quarter of a wavelength will arise, and it couples with the initial SAW generated by the interdigital transducers (IDTs) on the piezoelectric substrate, resulting in the change of trajectory of the wave particles and an acoustic wave velocity shift
The piezoelectric crystals used for the SAW sensors analyzed are YZ-LiNbO3, X-112°Y LiTaO3, ST-X quartz, and 128°YX LiNbO3, and the metallic dot materials are assumed as copper (Cu) and gold (Au), respectively

Summary

Introduction

The surface acoustic wave (SAW)-based micro rate sensor has gained increasing attraction for inertial navigation applications because it exhibits many unique properties such as superior inherent shock robustness, a wide dynamic range, low cost, small size, and long working life compared to other current gyroscope types [1]. Referring to a certain differential oscillation structure, the SAW micro rate sensor-based gyroscopic effect can be implemented. Lee et al first realized a prototype of a micro rate sensor based on SAW gyroscopic effect utilizing a temperature-compensated ST quartz substrate and a differential dual-delay-line oscillator configuration [4,5], but, the corresponding sensitivity was far too low, only 0.43 Hz·deg−1·s−1. Some other meaningful research works about SAW rate sensors were reported [7,8], it is obvious that there is still no tangible improvement in the sensor performance because of its very weak Coriolis force

Objectives

Results

Conclusion