Finite element modeling of capacitor micromachined ultrasonic transducers

A finite element model of cMUTs is constructed using the commercial code ANSYS. The complex load impedance seen by individual cells is compared with the plane wave real impedance seen by a parallel combination of the cells to make a transducer. The result shows the origin and level of crosstalk between array elements, with evidence of coupling through Stoneley and Lamb waves. For reduction of the crosstalk level, the effects of various structural variations of the wafer are investigated, which includes change of wafer thickness, etched trenches in the wafer and the walls between array elements.