A 2-DOF MEMS positioning system

We report on the design, fabrication, and testing of a 2 degree of freedom MEMS positioning system. Sandia National Laboratories' MEMS foundry process was utilized for the fabrication of the device; this process incorporates five layers of polysilicon and four sacrificial layers of silicon dioxide. The actuation was achieved by identical comb-drives on both axes. The comb drives produce a displacement of ∼ 4 μm which was amplified to ∼ 30 μm by the use of a distance multiplier. A pin and track arrangement in the X and Y arms, extending from the actuator assembly, allows bi-axis motion. The stage is connected to the central pin. For testing the performance of the fabricated design a custom made optical characterization setup was assembled. To provide the actuation signals to the stage, a Keithley 2400 source meter was programmed using LabView to provide actuation voltages from 0-100 V with a 2 volt step. An optical microscope, interfaced with a Canon S5 IS digital camera, was used to record the actuation events for the measurement of in-plane displacement. Displacement at the various actuation voltages was obtained using a National Instruments' Vision image analysis software routine. The device has been tested and demonstrates a useful design for realizing a bi-directional 2-D positioning system. The positioning system is capable of 0 - 30 μm of motion in both the X and Y axes, with displacement showing a quadratic relationship with the applied voltage.