Design, fabrication, position sensing, and control of an electrostatically-driven polysilicon microactuator

This paper describes the design, fabrication, position sensing, and control of an electrostatically-driven microactuator. The polysilicon microactuator, together with an on-chip electronic buffer, were fabricated by the Modular Integration of CMOS and microStructure (MICS) technology. The microactuator has a linear dimension of 310 μm×340 μm×1.7 μm and a “long throw” range of motion of ±4 μm. The driving comb fingers of the microactuator can generate up to 0.3 μN of electrostatic force, which is able to pull the suspended microactuator across the substrate at an acceleration of over 270 G's. The lateral position of the microactuator, relative to the substrate, is capacitively sensed by a Kalman filtering scheme, which achieves a position estimation error covariance below 0.01 μm RMS. A state-variable feedback loop operates at a closed loop bandwidth of over 11 kHz. Experimental results are given