Novel polysilicon comb actuators for xy-stages

Different types of polysilicon comb actuators have been designed, fabricated, and operated. The design was based on a finite-element stiffness modeling of the suspensions. In particular, a new straight beam structure showed an improved mechanical stability compared with the classical folded beam actuators. IC-compatible sacrificial layer technology was used for the fabrication of the polysilicon structures. Electrostatic actuation of the straight beam elements resulted in displacements as a function of the applied voltage; a maximum of 2.7 μm was achieved for 200 V. To lower this rather high driving voltage, the authors propose a comb actuator where several combs are placed in parallel to form a sarcomere actuator. By assembling four actuators, a comb-driven xy-microstage has been realized. Mechanical operation of this microrobot allowed the positioning of the center stage at any point in a 30 by 30 μm area. Electrostatically the table was moved up to 1 μm in each of the four directions