Miniature bulk PZT traveling wave ultrasonic motors for low-speed high-torque rotary actuation.

Traveling wave ultrasonic micromotors fabricated from a single layer of homogeneous bulk piezoelectric lead zirconate titanate (PZT) are described. The miniature motors are capable of bi-directional rotary motion with controllable speeds. By taking advantage of transverse interdigitated electrodes to excite traveling waves in a patterned bulk PZT substrate, the monolithic micromotor stators are patterned using a simple and low cost fabrication technique based on micropowder blasting. Performance of the ultrasonic micromotors is explored using devices with integrated glass rotors, using defined preload forces applied between the microfabricated stator and rotor elements. For the case of a 4.12 mm diameter PZT stator, a maximum speed of 30 rpm and stall torque of 501 mN · mm are achieved when applying a 323 mN preload force to the rotor.