A piezoelectric micromotor based on acoustic precessional waveguide

The piezomotor is composed of a stator, a steel axle, and a rotor. In the stator, which consists of a piezoelectric membrane, a flexural traveling wave is excited via piezoelectric effect. The rotating flexural displacement of the membrane excites a wide precessional wave in the axle; this wave propagates as in a waveguide, producing a precessional motion in the terminal surface of the axle. The rotor consists of a cylindrical permanent magnet, pressed in contact with the top surface of the axle by means of the magnetic force. In this way, a continuous slipping takes place between the terminal surface of the axle and the rotor. We demonstrate that the acoustic waveguide can transfer a good mechanical power (max torque 1.5x10(-5) Nm, max rotational velocity 3500 rpm) with unique design flexibility in a variety of different microsystem applications. (C) 1999 American Institute of Physics. [S0003-6951(99)02633-9].