Heat generation in PZT MEMS actuator arrays

Abstract

Piezoelectric microelectromechanical systems (piezoMEMS) enable dense arrays of actuators which are often driven to higher electrical fields than their bulk piezoelectric counterparts. In bulk ceramics, high field driving causes internal heating of the piezoelectric, largely due to field-induced domain wall motion. Self-heating is then tracked as a function of vibration velocity to determine the upper bound for the drive levels. However, the literature is limited concerning self-heating in thin film piezoMEMS. In this work, it is shown that self-heating in piezoMEMS transducer arrays occurs due to domain wall motion and Ohmic losses. This was demonstrated via a systematic study of drive waveform dependence of self-heating in piezoMEMS arrays. In particular, the magnitude of self-heating was quantified as a function of different waveform parameters (e.g., amplitude, DC offset, and frequency). Thermal modeling of the self-heating of piezoMEMS using the measured hysteresis loss from electrical characterization as the heat source was found to be in excellent agreement with the experimental data. The self-heating model allows improved thermal design of piezoMEMS and can, furthermore, be utilized for functional heating, especially for device level poling.