High-Temperature Microwave Acoustic Vibration Sensor

High-temperature vibration sensors are desired in a number of contemporary harsh-environment applications, namely: power plants, metallurgy, aerospace, and defense. The detection of vibrations in these applications is important for providing condition-based maintenance (CBM) for electronic, mechanical, and structural systems, thus reducing operating and maintenance costs, improving industry efficiency, and increasing safety. Microwave surface acoustic wave resonator (MSAWR) sensors have the potential of being used as high-temperature vibration sensors due to their proven harsh-environment operation, small size, battery-free, and wireless capability. This paper explores the MSA WR as a vibration sensor mounted and tested up to 500°C. A 193MHz langasite-based MSA WR sensor was attached to a custom-designed constant-stress Inconel cantilever test beam using a high-temperature capable A1 2 O 3 -based adhesive. The bam was mounted in a box furnace and exposed to vibrations using a stainless-steel rod attached to a vibration generator outside the furnace. The resulting measurements at high-temperatures reported in this paper confirm the viability of the MSA WR sensor to detect both vibration frequency and magnitude for high temperature industrial, defense, aerospace, and power sector applications.