The development of wireless energy transfer is critical to the promotion of implantable medical devices (IMDs). In this paper, an aluminum nitride (AlN) based piezoelectric micromachined ultrasonic transducer (pMUT) array is designed, fabricated and characterized, which can be a potential power supply for IMDs. The pMUT array is ideally suitable for integration with wireless-powered system since it is fabricated from miniaturized AlN membrane array of 4×4 units. Both the simulation and experiment are conducted to characterize the pMUT device. The transmitting sensitivity of the fabricated pMUT array is measured as 83 nm/V at a resonant frequency of 527 kHz.