LAUSR

Residual stress dramatically affects the performance of piezoelectric micromachined ultrasonic transducers (pMUTs), in particular, the transmitting sensitivity. This letter presents a novel architecture for pMUTs with V-shaped springs. Stiffness modification achieved by the V-shaped springs contributes to localize the residual stress, resulting in a flat vibrating membrane rather than a curved one. The experimental results show that the initial deflection of the vibration membrane is less than 10 nm or 0.004% (deflection/membrane size) for the enhanced pMUT. Leveraging on the flat vibrating membrane, the transmitting sensitivity of the enhanced pMUT is 50.9 nm/V, which is 203% higher than the pMUT without springs. Combining with the piston-like mode shape, the output sound pressure of the pMUT can be improved by around 23 dB.