Ionic Liquid Lubrication of MEMS Devices: An AFM Based Analysis and Evaluation on Test Devices (Preprint)

摘要

Lubrication of Micro Electro Mechanical Systems (MEMS) became very important as the devices became complex and more and more parts had interacting areas. In previous reports, self-assembled monolayers and long chains of flurocarbons were used to lubricate MEMS components with significant success. In this report, a method based on atomic force microscopy is described that measures and compares ionic liquid lubricity. Effect of ring structure is studied in the case of substituted pyridinium and imidazolium rings as cations in ethyl methyl pyridinium and ethyl methyl imidazolium ethyl sulfate. Effect of alkyl chain length on friction was studied for butyl methyl pyrrolidimium and hexyl methyl pyrrolidinium bis(trifluro methyl sulfonyl) imide. Some of the ionic liquids that exhibited promising results from AFM study are tested on MEMS test devices. The friction and wear data obtained for these liquids applied on hydrogenated silicon showed ample correlation to the failure life span of hydrogenated MEMS test devices. This shows that AFM-liquid cell based tests of ionic liquid lubricity is a good characterization technique for screening lubricants for MEMS devices.