Position Sensing And Control Of Electrostatically-driven Polysilicon Microactuators

Abstract

This paper reports on the position sensing and control of a polysilicon microactuator built by silicon surface micromachining technology. A top view photograph of the actuator is shown in Fig. 1. The actuator can be seen as a square skeleton which has a lateral dimension of 300 p m . The moving parts are 1.7 p m thick and are 2 p m away from the silicon substrate. The actuator is allowed to move f 4 pm laterally from its nominal position. The actuator is composed of four parts: anchors, springs, body, and fingers. Four anchors attach all other moving parts to the substrate. The four springs are slender polysilicon flexures that extend from the anchors to the body, usually in a multiple-folded fashion. The body is the square frame that connects all other parts and provides mechanical rigidity. Two additional vertical cross bars extend from top to bottom to carry the sensing fingers.