Lubrication of MEMS by ionic liquids

COLL 161

Jeffrey S. Zabinski1, K. C. Eapen2, Benjamin S. Phillips3, Robert A. Mantz2, and Jose J Nainaparampil2. (1) Tribology and Coatings, Air Force Research Laboratory, 2941 Hobson Way, Bldg. 654, Room 136, Wpafb, OH 45433-7750, (2) AFRL/MLBT, Air Force Research Laboratory, Wright Patterson Air Force Base, Ohio, Bldg. 654, Rm 136, 2941 P Street, Wright Patterson AFB, OH 45433, (3) Systran Corporation, 4126 Linden Avenue, Dayton, OH 45432
Lubrication of MEMS devices is critical for controlling friction, stiction, and wear problems that prevent reliable operation. Hard coatings and monolayer film strategies have been partially successful in controlling tribological problems, but hard coatings are difficult to apply uniformly, and monolayer films wear away too quickly. Combinations of bound and mobile monolayers have significantly improved device durability by providing lubricant replenishment. In this study, ionic liquids were used to lubricate model Si surfaces and MEMS devices. Functional groups were selected to allow for covalent bonding of one ion while the counter ion was mobile. Durability was assessed in device studies and lubrication mechanisms were explored in AFM/LFM experiments on model surfaces. Results are compared to hydrocarbon and fluorocarbon bound/mobile lubricant systems. Ionic liquids significantly increased durability and results will be explained in terms of surface chemistry and mobility.