Analysis of pre-stress impact on stiffness and performance in PMUT devices

Abstract Pre-stress affects the performance of piezoelectric micromechanical ultrasonic transducers (PMUTs), but the influence mechanism of pre-stress is not deeply discussed. This research examines the impact of pre-stress on PMUTs with different structures and sizes through simulations, theoretical calculations, and experiments. The findings reveal that pre-stress mainly influences PMUTs based on stiffness, with lower stiffness devices undergoing greater neutral axis shifts under stress. These shifts lead to notable changes in stiffness, resonance frequency, and electromechanical coupling coefficient. Under 45 MPa tensile stress, the stiffness change rate for clamped and pinned PMUTs is 12.16% and 57.42%, respectively, with pinned structures showing 2–3 times larger changes in frequency and coupling coefficient. Applying a DC bias of ±40 V to simulate pre-stress shows that pinned PMUT frequency deviations three times greater than clamped ones, with stiffness change rates of 61.08% and 9.87%, respectively. This study offers valuable insights for evaluating stress in industrial PMUT applications.