High Temperature Surface Acoustic Wave Sensor with Strain Isolation Structure

This paper presents a high temperature surface acoustic wave (SAW) sensor with less strain sensitivity. To realize more accurate temperature measurement, a strain isolation structure is designed to alleviate the transfer of inevitable substrate strain to the sensing unit. Langasite (LGS) piezoelectric substrate and composite film electrode are used to ensure the high temperature stability of the sensor. FEA simulation shows the strain isolation effect of the presented structure. Compared with the ordinary sensor, the strain sensitivity of the presented sensor is reduced from 0.1761 to 0.0025 kHz/us. The output presents a quadratic function relationship with temperature in 80-850°C, and an error of less than 5%. is achieved.