Beamforming with AlN-based bimorph piezoelectric micromachined ultrasonic transducers

In this paper, we demonstrate a multi-membranes piezoelectric micromachined ultrasonic transducer (pMUT) device devoted to air-borne pulse-echo measurement with an angular resolution of 18 degrees. The setup includes a one-dimensional pMUT array of 5 bimorph AlN-based membranes working at 113.6 kHz for reception and a single pMUT membrane for emission. Pulse-echo measurement are achieved on an acoustic target located at 40 cm from the device. A beamforming strategy is implemented to achieve spatial filtering of the signal. The angle of the acoustic beam is manually defined and clearly evidenced by signal processing, confirming experimentally the potential of pMUT device for air-borne beamforming-based system.