Development of a fluid-driven microactuator

In this paper we describe a new design of a fluid-driven microactuator which comprises a planar piston, a four-way control valve, and a mechanical feedback system that controls the output in accordance with an input displacement. Merits of this design are expected in terms of output density, scalability, and feedback ability realized with no electronic devices. Fabrication processes of the microactuator include bulk micromachining of two sheets of silicon substrate and their assembly by electrostatic bonding to glass plates. The output characteristics were measured while compressed air was supplied. Generated output force showed an almost linear relationship to supplied pressure and to valve displacement. However, the magnitude was asymmetric in terms of driven directions, which resulted from geometrical configuration essentially introduced by an anisotropic etching of the silicon substrate. The position of the output shaft was sufficiently controlled with a designed magnification factor multiplied to the input displacement in both static and dynamic senses.