In-situ Performance Evaluation of silicon-Based Ultrasonic Transducer Under Extreme Thermal Conditions

Recently, ultrasonic transducers have been widely used in nondestructive testing for critical industries requiring accurate structural and functional monitoring. However, piezoelectric materials, such as lead zirconate titanate (PZT), commonly used in transducers, have limitations at high temperatures due to depoling issues, which hinders their use in in-situ extreme conditions. Capacitive micromachined ultrasonic transducers (CMUTs) offer an alternative, providing better thermal stability, but the actual validation of CMUT for in-situ thermal conditions has not been proved in preliminary studies. In this study, a silicon-based CMUT array was tested at temperatures up to 180 ºC, showing minimal performance degradation with only a 27.6 % reduction in maximum displacement and a 2 % resonance frequency shift, which highlights the potential of CMUT for reliable, high-temperature operation in critical applications, especially in nondestructive testing.