Transmitting Sensitivity Enhancement of pMUTs via Releasing Residual Stress by V-Shaped Springs

Residual stress can dramatically hamper the performance of piezoelectric micromachined ultrasound transducers (pMUTs), in particular the transmitting sensitivity. This paper reports a series of square pMUTs with enhanced transmitting sensitivity through V-shaped springs in different angles. The V-shaped springs can release the residual stress through self-deformation, which contributes to a flat vibrating membrane rather than a curved one. A flat vibrating membrane conduces to a large vibration amplitude. Consequently, the transmitting sensitivity of the pMUT with 150° V-shaped springs is measured as 50.9 nm/V, which is 203% higher than that of the pMUT without springs. The enhanced pMUTs have advantages in various applications of emission ultrasound.