A gas-expanded liquid nanoparticle deposition technique for reducing the adhesion ofsilicon microstructures

Abstract

A gas-expanded liquid-based nanoparticle deposition technique was integrated with acritical point drying process to modify the surface of polysilicon microstructures in order toreduce the adhesion that ordinarily occurs due to dominant interfacial surface forces.Dodecanethiol-capped gold nanoparticles (AuNPs) were deposited onto arrays of cantileverbeams using gas-expanded liquid technology in an effort to increase the surfaceroughness, thereby reducing the real contact surface area as well as changing thechemical constituents of the contacting areas. Both AuNP-coated and uncoated(native oxide surface) arrays were actuated electrostatically in order to determinethe work of adhesion. The results of this study indicate that while cantileverbeams with only their native oxide exhibit apparent adhesion energies of about700 ± 100 µJ m−2, cantilever beam arrays coated with AuNPs exhibit an apparent adhesion energy of about8 µJ m−2 or less. These results indicate that metallic nanoparticle coatings can be successfullyapplied to micromachines and provide a drastic reduction in apparent adhesion energy.