Development of an electrostatic linear actuator by micromachining processes

The dimension of the developed electrostatic linear actuator is 3 mm×4 mm×14 μm. It consists of upper and lower stators of a comb shape and a ladder-shape slider between the stators. The actuator was fabricated on a Si substrate using a multilayered film of Si₃ N₄ and SiO₂ for the structure, AlSi as electrodes and polyimide as sacrificial layers using semiconductor process technology. The relation between driving force and displacement of the slider was revealed by numerical simulation of the electric field by the infinite integral method. The results show that a constant driving force of 1.49×10^-5 N is obtained by changing electrodes of voltage application by every 15 μm motion of the slider, that the maximum driving force is 2.89×10^-5 N which is enough to drive the actuator, and that the optimum pitch ratio of the slider and the stator is 4:3