Low friction liquid bearing mems micromotor

This paper examines the performance of rotating microdevices incorporating a liquid bearing to couple a rotating element to a fixed substrate. Liquid bearing technology promises to significantly improve the durability and lifetime of micromechanical motors. Here, the fluid is confined between the rotor and stator using surface patterning of a hydrophobic layer. Magnetic actuation of 10 mm diameter silicon rotor is used to characterize the liquid bearing motor at rotation rates up to 1800 rpm. Bearings with fluid thickness from 20-200 microns are characterized. A minimum torque of 0.15 μN-m is required to overcome static friction and initiate rotation. At rotation rates above 720 rpm, the rotor wobble is less than ±1 mrad and the bearing exhibits viscous friction with a drag coefficient of 1.2 × 10^-3 μN-m/rpm.