A Wireless Surface Acoustic Wave-based Tire Pressure and Temperature Sensing Module

Abstract

Based on the piezoelectric and temperature effects of lithium niobate (LiNbO3) wafer, this paper presents a design of a one-port resonator-type interdigital surface acoustic wave-based sensing device with a wireless transmission function for measuring vehicle tire pressure and temperature. The sensing components of the proposed device comprised a double-layered 3-D structure for measuring pressure and temperature changes simultaneously. The pressure-sensing film on the top layer of the wafer was formed by anisotropic back-etching. This feature enhanced the sensitivity of the device by 33% compared with sensing components featuring planar structures. Furthermore, the sealed bottom layer of the wafer served as a linear temperature sensor. The proposed sensing module was characterized as having a temperature sensing range of 25-95 °C with sensitivity 4.05 kHz/°C and pressure sensing range of 0-5 bar with sensitivity 8.19 kHz/bar.