An Experimental and Numerical Study of Crosstalk Effects in PMUT Arrays

This study provides a comprehensive characterization of a 4 x 4 piezoelectric micromachined ultrasonic transducer (PMUT) array suited for in-air applications. Crosstalk can be viewed as a lack of isolation among the transducers, with possible reasons, including the electrical, acoustic, and structural coupling among the transducers. This study focuses on acoustic coupling as the primary cause of crosstalk, since the influence of electrical and structural coupling on crosstalk is shown to be negligible by comparing experimental tests and numerical analysis conducted in vacuum and in air. It is expected that acoustic coupling among diaphragms occurs due to air-connected cavities. Consequently, several scenarios are investigated in which the cavities are either partially or completely acoustically disconnected. The computed response spectra of the PMUTs demonstrate that the presence of secondary peaks, which indicated the presence of crosstalk, is diminished when the PMUTs are decoupled partially or completely as compared with an open cavity. The conducted acoustic tests also demonstrated that crosstalk impacts the intensity and directivity of the acoustic wave produced by the array.