Design and testing of a 4-mm3 bidirectional linear microfin actuator

A new linear microactuator, using bulk PZT and electro-discharge-machined components, generates a sliding velocity and force of 100 mm/s and 12 mN in either direction, and a peak velocity and force of 212 mm/s and 44 mN, is an order of magnitude smaller than any other reported piezoelectric linear actuator to date at less than 4 mm³ in volume. Using a simple combination of two slightly different fins, placed in contact with a slider, and vibrated at two different resonance frequencies, 508 and 522 kHz, by a specially-designed, axially-vibrating piezoelectric element, bidirectional linear motion was obtained. By simply reducing the length of the applied signal, the sliding distance was reduced to 90±2 nm, which could be improved with a variety of control methods. The design offers not only silent operation, slider clamping upon removal of power, and all the other advantages of piezoelectric actuators, but also the potential to be further reduced in size to sub-mm³ for microrobotics and other applications.