Dual-mode CMUT structure sensor for high hydrostatic pressure measurements: conventional and collapse modes

Capacitive Micromachined Ultrasonic Transducer (CMUT) are widely utilized in fields such as medical imaging, non-destructive testing, and chemical sensing for active sensing applications. However, the capacitive structure of CMUT also demonstrates significant potential in the domain of passive pressure sensing. This study is the first to apply the CMUT structure to passive pressure sensing in high hydrostatic pressure environments. The CMUT pressure sensor, fabricated using MEMS technology, demonstrates high consistency, with a maximum static capacitance deviation of only 1% among multiple sensors. Experimental results from high hydrostatic pressure testing indicate that the sensor can reliably measure pressures exceeding 20 MPa with real-time responsiveness. After being placed in a dynamic pressure chamber for three months, the sensor's pressure measurements remained consistent with the initial results, exhibiting a maximum deviation of just 0.65%, demonstrating excellent repeatability. These experiments confirm the high reliability and outstanding long-term stability of the sensor, laying a foundation for CMUT structure applications in high hydrostatic pressure sensing.