Micromachined ultrasonic motor based on parametric polycrystalline silicon plate excitation

This paper reports on novel ultrasonic actuation of a surface micromachined motor using substrate vibrations. The rotor thickness and diameter are 2.5 and 1000 μm, respectively, and is actuated by a piezoelectric lead-zirconate-titanate (PZT) plate with segmented electrodes. The motor operates with sub-three volt peak-to-peak excitation in atmospheric pressure. This low voltage operation is enabled by the use of parametric excitation of rotating plate vibrations. The rotation direction of the motor can be controlled by selectively exciting different electrodes on the PZT plate. The piezoelectric plate is adhesively mounted to silicon die after the surface micromachine fabrication making the method suitable for actuating micromachines from any surface micromachine process.