Piezoelectric Micromachined Acoustic Transducer with Electrically-Tunable Resonant Frequency

A Piezoelectric Micro Electro-Mechanical System (Piezo-MEMS) acoustic transducer able to electrically tune the resonant frequency in receiver and transmitter modes is reported. The proposed 6×6mm squared diaphragm has been simulated by a 2D finite element model, fabricated, and measured. A DC bias voltage applied to the piezoelectric layer produces a controllable stress, thus leading to a matching of the series and parallel resonant frequencies. This allows to increase performances when the transducer is operated as both transmitter and receiver. The resonance can be tuned in a range of ±70 Hz by a DC voltage of ±8 V with an estimated sensitivity of 8.87 Hz/V.