In-Water Characterization of Capacitive Micromachined Ultrasound Transducers Produced on Glass for Medical Imaging

We present the fabrication and characterization of capacitive micromachined ultrasound transducers (CMUTs) on glass substrates. The devices exhibit electromechanical coupling efficiency, fractional bandwidth, and transmit sensitivity comparable to state-of-the-art silicon-based CMUTs for an in-water frequency range of 4 - 12 MHz. Performance improves with higher DC bias, though dielectric charging may affect long-term stability. The used process flow is compatible with existing flat-panel display production lines, paving the way for large-area and flexible transducer arrays tailored for continuous ultrasound monitoring in and outside hospitals.