High temperature effects on surface acoustic wave strain sensor

Abstract

Surface acoustic wave sensors (SAW), as a wireless passive sensor, are susceptible to temperature disturbance for high-temperature strain measurements, which results in poor accuracy and repeatability of the strain sensing. This paper investigates temperature effects on SAW strain sensors. Results show that high temperature not just induces frequency drift, but also reduces strain transfer ratio due to glue softening. The resonant frequencies of the langasite (LGS) SAW sensor have a linear relationship with strain for fixed temperatures, while the strain sensitivity is greatly affected by temperature. The results also show that the difference of measured strain sensitivities between the two resonant frequencies for one device is much less affected by temperature because they suffer the same strain transfer ratio and temperature characteristics, but different strain responses. A method to eliminate temperature effects has been proposed and accurate high-temperature strain measurements with SAW sensor were conducted to extend strain range up to 380 με with high repeatability under 500 °C.