Fabrication and Characterization of Micromachined Piezoelectric T-Beam Actuators

This paper presents a monolithically fabricated microelectromechanical piezoelectric cantilever beam with a T-shaped cross section capable of in-plane and out-of-plane displacements and sensing. High-aspect-ratio T-beams are achieved by direct micromachining of bulk lead zirconate titanate (PZT-4) via reactive ion etching of 65-mu m-deep features. Electrodes deposited on the top and bottom web and flange regions of the T-shaped structure allow in-plane and out-of-plane motion actuation and sensing. The T-beam structures were tested for in-plane and out-of-plane tip displacements, out-of-plane blocking force, and impedance response. These results are explained using analytical models that predict static deflection, blocking force, and resonance frequency. Nine prototype micromachined T-beams are fabricated that achieve up to 129 mu m of out-of-plane displacement, 11.6 mu m of in-plane displacement, and 700 mu N of out-of-plane blocking force.