Modeling, Fabrication and Characterization of Piezoelectric ZnO-Based Micro-Sensors and Micro-Actuators

In this study, capabilities of zinc oxide (ZnO) thin films in sensing and actuating were investigated using micromachined micro-cantilevers. A heterogeneous piezoelectric cantilever was modeled to study its response under voltage and/or external mechanical loading. A ZnO thin-film micro-cantilever was designed based on the developed theoretical model. Simulated tip deflections of the micro-cantilever were on the nanometer level under typical electrical and mechanical input. A prototype was fabricated with microfabrication techniques. The ZnO thin film was sputtered at room temperature and demonstrated good compatibility with common chemicals and processes in micromachining. The fabricated micro-cantilever was experimentally characterized for its actuating and sensing performance. For actuator characterization tip deflection of the micro-cantilever was detected by a laser Doppler vibrometer, while for sensor characterization the micro-cantilever was calibrated as an acceleration sensor using a reference accelerometer. The experimental resonant frequency, actuating and sensing sensitivities agreed well the design specifications.