Temperature compensation of surface acoustic wave strain sensors on 122° X-cut lithium tantalate substrate at high temperatures

We report a temperature compensation method for surface acoustic wave (SAW) strain sensors that accounts for the thermal expansion effects of the measured object. This approach effectively reduces the cross-sensitivity error of the SAW sensors at elevated temperatures caused by the thermal expansion of the target substrate. Experiments were conducted using SAW sensors fabricated on 122° X-cut lithium tantalate substrates. The temperature and strain response characteristics of the LT SAW sensor were experimentally analyzed over a temperature range of 25 °C–140 °C and the results showed that the resonant frequency decreased linearly with increasing temperature. In addition to the intrinsic temperature response of the LT SAW sensor, the cross-sensitivity error induced by the thermal expansion in the measured object was identified as a major source of measurement error. A dual-sensor differential structure was implemented to quantify the strain interference caused by the thermal expansion of the measured object. A temperature–strain coupling model of the measured object was established using finite element simulation. A resonant frequency correction formula incorporating temperature compensation was proposed. The experimental results show that the measurement error of the sensor using the proposed temperature compensation formula was only 9.13% at 120 °C, demonstrating the effectiveness of the method. This study provides theoretical and technical support for high-precision measurement of SAW strain sensors in high temperature environments.