Design and implementation of an on-chip polymer micro ball bearing

This study presents a novel design and fabrication process to realize an on-chip micro ball bearing. The ball bearing consists of a polymer-Si-polymer outer-race (stator), and a suspended polymer-Si-polymer inner-disk (rotor) supported by polymer micro-balls. The outer-race and inner-disk are demolded from silicon mold, which is patterned by wet isotropic etching on double-polished 525 μm-thick silicon wafer. The liquid phase photocurable polymer balls are dispensed by commercial dispenser with a hundred micrometer diameter tip and in-situ self-assembled in buffer liquid. After photocurable polymer solidified by UV-curing, the polymer balls are confined between the outer race and inner disk. Note the ball bearing is fabricated on a single wafer with no assembly required.