Design, fabrication and testing of a silicon-on-insulator (SOI) MEMS parallel kinematics XY stage

This paper presents the design, kinematics, fabrication and characterization of a monolithic micro positioning two degree- of- freedom translational ( XY) stage. The design of the proposed MEMS ( micro- electro- mechanical system) stage is based on a parallel kinematics mechanism ( PKM). The stage is fabricated on a silicon- on- insulator ( SOI) substrate. The PKM design decouples the motion in the XY directions. The design restricts rotations in the XY plane while allowing for an increased motion range and produces linear kinematics in the operating region ( or workspace) of the stage. The truss- like structure of the PKM also results in increased stiffness by reducing the mass of the stage. The stage is fabricated on a silicon- on- insulator ( SOI) wafer using surface micromachining and a deep reactive ion etching ( DRIE) process. Two sets of electrostatic linear comb drives are used to actuate the stage mechanism in the X and Y directions. The fabricated stage provides a motion range of more than 15 mu m in each direction at a driving voltage of 45 V. The resonant frequency of the stage under ambient conditions is 960 Hz. A high Q factor (similar to 100) is achieved from this parallel kinematics mechanism design.