Piezoelectric micromachined ultrasonic transducer array for micro audio directional loudspeaker

A piezoelectric micromachined ultrasonic transducers(pMUT) array as the emitter of micro audio directional loudspeaker is studied to examine the feasibility of realizing in portable multimedia devices. The array element is multilayered that the circular PZT thin film with Au electrodes is adhered to the silicon on insulator. The radius and thickness effects of PZT and Si layer are studied and focused on the vibration characteristics which include first resonant frequency, electromechanical coupling coefficient and center flexural displacement. The directivity of the array is simulated. A 5*5 square array is fabricated and its impedance, sound pressure frequency response are measured and analysed. The experiment results indicate the feasibility of realizing the audio directional loudspeaker with low power consumption and micro size in portable multimedia devices as well as in mobile phone.