High-temperature vibration sensor based on Ba$_2$TiSi$_2$O$_8$ piezoelectric crystal with ultra-stable sensing performance up to 650°C

High-temperature vibration sensors are needed for precise monitoring of dynamic mechanical conditions in aerospace, automotive, and energy-generation-related systems. In this study, a compression-mode vibration sensor was designed and fabricated using a Ba $_2$ TiSi $_2$ O $_8$ (BTS) single crystal for structural health monitoring at elevated temperatures (650°C). The fundamental performance of the sensor was simulated, and the effect of pre-tightening torques on sensor performance was studied. Sensor performance was characterized as a function of temperature up to 650°C in a frequency range of 100-600 Hz. The sensitivity of the sensor was found to be on the order of 2.6-2.7 pC/g over the tested frequency and temperature ranges, with variation below 2%. In addition, the sensor was found to maintain ultra-stable sensitivity at 650°C. Thus, it exhibits good sensing capability and high reliability at elevated temperatures.