A normally latched, large-stroke, inchworm microactuator

This paper presents the successful demonstration of a large-stroke, high-precision inchworm microactuator. The actuator is capable of zero-power latching, or forcibly maintaining its position by using pre-stressed spring load. The actuator is driven by a combination of a PZT-stack actuator unit for slider thrust and electrostatic comb-drive units for slider grip. Incremental step size is precisely adjustable to the tens of nanometers level by controlling the PZT-stack actuator voltage. The observed minimum step size was 59 nm/cycle. Large stroke is obtained by repeating the operation sequence numerous times. A large-stroke actuation exceeding 600 νm has been demonstrated. There is no conceivable limit to the stroke except for the length of the slider and external load.