The influence of DC bias on the displacement and sensor output of self-sensitive piezoelectric microcantilevers

Abstract

The present study describes the influence of DC bias on the displacement and sensor output of self-sensitive piezoelectric microcantilevers that employ PZT thin films for an actuator and a sensor. The self-sensitive piezoelectric microcantilevers were fabricated via a microelectromechanical systems (MEMS) microfabrication process from a multilayer of Pt/Ti/PZT/Pt/Ti/SiO2 deposited on a silicon-on-insulator wafer. The microcantilever displacement and sensor output were measured under the application of sine wave and DC bias to the actuator PZT thin films. The amplitude of the sine wave was larger than the coercive voltage of the PZT thin films. Under the non-resonant actuation, the waveforms of the displacement and sensor output of the self-sensitive piezoelectric microcantilevers with DC bias application exhibited a normal sine wave, while those without DC bias application exhibited a distorted sine wave due to a polarization reversal. Under resonant actuation, the waveforms of the microcantilever displacement and sensor output with and without DC bias application exhibited a normal sine wave. It was found that the application of DC bias generates a larger sensor output and linearity to the actuation voltage, which is desirable for the feedback control of self-sensitive piezoelectric microcantilevers using sensor output.