Ultrasonically driven surface micromachined motor

The first-ever all-surface micromachined ultrasonic micro-rotor is presented. The rotor is actuated by electrically driving a piezoelectric PZT plate mounted at the back of the silicon die eliminating the need for interconnects and space consuming surface actuators. The rotor operates with a single phase sub-five volt peak-to-peak excitation in atmospheric pressure. The piezoelectric plate is adhesively mounted making the method suitable for actuating micromachines from any surface micromachine process. Two different modes of operation are demonstrated: pulsed and resonant. The pulse actuation results in low rotation rate (0.5-3 RPM) while resonant actuation results in a fast rotation (10-100 RPM). The ability to drive a geared down rotor (50:7), much smaller than the driving rotor indicates high torque output capability.