Effect of fluid losses and acoustic resonances in CMUTs with vented cavities

We report on capacitive micromachined ultrasonic transducers (CMUTs) with vented cavities for varying their bandwidth and sensitivity in airborne applications. The devices are simulated using a finite element model which incorporates viscous and thermal fluid losses in the squeeze film and the vent holes, as well as acoustic radiation and acoustic resonance in the backing. Our model accurately predicts the behavior of such CMUTs. The model is also validated with measurements at elevated pressure.