AlN PMUT-based Ultrasonic Power Transfer Links for Implantable Electronics

Abstract

The present work reports on the first demonstration of acoustic power transfer through the use of Aluminum Nitride (AlN) Piezoelectric Micro Machined Ultrasonic Transducer (PMUT) arrays at transmission distances suitable for intra-body powering applications. In contrast to Lead Zirconate Titanate (PZT), used as the piezoelectric in state-of-the-art devices, AlN offers higher biocompatibility and the possibility of single chip integration with Complementary Metal Oxide Semiconductor (CMOS) technology. An output power of 1 μW, from a minute (8 mm x 8 mm x 300 μm) PMUT array chip, was achieved on an optimal 330 Ω load. The operating frequency was 2 MHz, through a distance of 4 cm, in an oil medium resembling intra-body conditions. This implementation is a critical step towards increasingly miniaturized, highly integrated implantable circuits.