The investigation of integrated SAW strain sensor based on AlN/TC4 structure

Abstract This paper reports a novel strain sensor integrated on metal component. High-performance SAW strain sensor is embed on the layered AlN/TC4(Ti-6Al-4 V) structure by lift-off photolithography techniques, while the AlN film is directly deposited on the TC4 metal beam without bonding materials. The strain characteristics of the integrated sensor have been simulated and experimental investigated. The finite element modeling (FEM) simulation reveals that the strain transfer ratio (STR) of the sensor reaches 0.992 at 20 °C. The experimental results show that the strain sensitivity of the sensor reaches 1.61 ppm/μe with a deviation of 0.56%. The strain hysteresis error of the SAW devices is about 0.32% at 25 °C. The temperature behavior in strain sensitivity and hysteresis errors have also been studied. Though negative effects caused by increasing of operation temperature on its strain response, the integrated SAW sensor shows better performance than the reported one in a wide range of operation temperature. The prepared layered SAW sensor integrated with TC4 alloy has great potential applications in high temperature harsh environment.