Design Analysis of Capacitive Micromachined Ultrasonic Transducers

Currently, capacitive micromachined ultrasonic transducers (CMUTs) have emerged as an alternative to the well-established piezoelectric micromachined ultrasonic transducers (PMUTs). The micromachining technology has attracted MEMS researchers to test the capabilities of CMUT devices to be introduced in various ultrasonic applications. This research presents design characterization and simulations of three cell geometries: square, hexagonal, and circular, to highlight factors influential for CMUT operation. CMUT cells are analytically modeled and simulated by finite element modeling with COMSOL Multiphysics to highlight the factors influencing acoustic pressure outputs. The hexagon membrane has the highest array packaging density while the more flexible circular membrane has the least amount of stress to operate. This research introduces factors significant for determining the optimal CMUT design for applications with operating frequency of 1.5 MHz.