Dynamic FEM analysis of multiple cMUT cells in immersion [capacitive micromachined ultrasonic transducers]

This paper reports on the accurate modeling of immersion capacitive micromachined ultrasonic transducers (cMUTs) using a time-domain, nonlinear FEM package. A cMUT device consists of many cells. In this paper, a square membrane was used as the unit cell to cover the transducer area by periodic replication on the surface. The FEM calculations were used to analyze the nonlinear operation regimes of the cMUT. Nonlinear operation regimes (collapsed and collapse-snapback) provided higher acoustic output pressures than the conventional operation. The FEM calculations were compared to transmit experiment results performed with a hydrophone, and good agreement was observed.