Characterization of an inchworm actuator fabricated by polysilicon surface micromachining

摘要

We describe the design, fabrication, test and preliminary analysis of a polycrystalline silicon MEMS inchworm actuator fabricated in a five level surface micromachining process. Large force generation (500 micronewtons), large range of motion (+-100 microns), small area requirements (600 X 200 um), small step size (10, 40 or 120 nanometers), and a large velocity range (0 to 90 microns per second) are demonstrated. We characterize force with a load cell whose range is calibrated on a logarithmic scale from micronewtons to millinewtons. We characterize out-of-plane displacement with interferometry, and in-plane displacement with Moire metrology sensitive to ～60 nm. The actuator serves well for testing friction under conditions of well-known applied pressure. We found that our surfaces exhibited a static coefficient of friction (cof) of ～0.3, and a dynamic cof of ～0.2. We also present initial wear studies for this device.