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 μm has been demonstrated. There is no conceivable limit to the stroke except for the length of the slider and external load. (Some figures in this article are in colour only in the electronic version)