Polymer PMUT array for high-bandwidth underwater communications

Abstract

This paper demonstrates an 11-by-11 PMUT array used as a high-bandwidth receiver and transmitter developed for underwater communications. The array is composed of a randomized distribution of elements with three different diameters. While each individual element has its own unique resonance frequency - around 61, 66 or 73 kHz depending on its dimensions - and a bandwidth around 5 kHz in water, the combination of multiple sizes within the same array is shown to result in an average frequency response exhibiting a single resonance peak around 63 kHz with a fractional bandwidth up to 18% in water. A transmit efficiency of 1.6 Pa/V is achieved at 10 cm, combined with a receive sensitivity of 0.23 mu V/Pa.