Flexible piezoelectric micro ultrasonic transducer array integrated on various flexible substrates

Abstract

Flexible ultrasonic transducers have attracted much attention in industrial and biomedical applications. However, most of them are fabricated based on a single substrate by complex micromachining techniques. In this paper, a bending mode based flexible piezoelectric micro ultrasonic transducer (PMUT) array has been designed and fabricated through an improved simple and robust adhesive bonding fabrication process. The developed flexible PMUT array consists of 3 × 3 elements and its resonant frequency is about 161 kHz. Our device can be fabricated on various flexible substrates and pasted on concave, convex, and undulant surfaces, reaching an output signal of 75 mVpp under 100 Vpp excitation. The characterizations of the device were performed to verify its excellent flexibility, mechanical stability, and lifespan. Its acoustic performance was also evaluated using diverse time of flight (TOF) tests in air ambient, demonstrating its potential use in flexible acoustic devices or wearable range finder.