Enhanced VZO-Based PMUT for Advanced Acoustic Sensing

Piezoelectric micromachined ultrasonic transducers have become highly attractive for applications such as intravascular ultrasound, marine exploration, and other forms of high-resolution acoustic sensing owing to their low power requirements and compact footprint. In this work, a vanadium-doped ZnO (VZO) PMUT is presented, which features a piezoelectric coefficient of 121±/V and a dominant crystallographic orientation. The device incorporates a 6 × 6 circular membrane array structure, which enhances the overall acoustic sensitivity through parallel reception and signal accumulation. The resonant frequency of the device is around 477 kHz in air, shifting to approximately 295 kHz when immersed in water. Experimental testing indicates that the receiving and transmitting sensitivity of the proposed device are as high as -140 dB(re. 1V/μ Pa) and 119 dB(re. 1 μPa/V), respectively, which are superior to the majority of PMUTs. Its ability to operate at low drive voltages enables reliable detection of weak acoustic signals. The combination of a minimal form factor and enhanced electromechanical coupling positions VZO-based PMUT arrays as promising candidates for critical applications.