Faculty

Associate Professor Seong H. Kim | Research

Nanotribology Research

Gas Phase Lubrication of MEMS devices

Water and other small volatile organic molecules have the propensity to adsorb onto solid substances with high surface energies and change interfacial properties. These changes become a dominating factor in engineering micro- and nano-scale systems. In the case of organic molecules, such as alcohols, the adhesive force of the silicon oxide nanoasperity contact decreases as alcohol adsorbs onto oxide surfaces. This is mainly due to formation of an organic monolayer on the surface. However, the effect of water adsorption on the nanoasperity adhesion force for hydrophilic surfaces such as silicon oxide or mica is quite different and complicated. The observed trend shows the adhesion force as a function of humidity initially increases, reaches a maximum value, and then decreases. The origin of this complicated RH dependence is due to the presence of ice-like structured water and the viscoelastic behavior of the adsorbed water layer. The adsorption alcohol vapor on the surface prevents the ice-like structure formation of water molecules and significantly reduces adhesion, friction, and wear.

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of a Micro Nano article about this research.

References:

1. Asay DB, Dugger MT, Ohlhausen JA, & Kim SH, "Macro - to Nano-scale Wear Prevention via Molecular Adsorption" Langmuir (in press).
2. Asay DB & Kim SH, "Molar Volume and Adsorption Isotherm Dependence of Capillary Forces in Nano-asperity Contacts" Langmuir (in press).
3. Kim SH, Asay DB, & Dugger MT, "Nanotribology and MEMS" Nanotoday 2 (5): 22-29 2007.
4. D. B. Asay and S. H. Kim, "Direct Force Balance Method for AFM Lateral Force Calibration" Rev. Sci. Instrum. 2006, 77, 043903.
5. D. B. Asay and S. H. Kim, "Effects of Adsorbed Water Layer Structure on Adhesion Force of Silicon Oxide Nano-asperity Contact in Humid Ambient" J. Chem. Phys. 2006, 124, 174712.
6. K. Strawhecker, D. B. Asay and S. H. Kim "Gas-Phase Lubrication of MMES Devices: Using Alcohol Vapor Adsorption Isotherm for Lubrication of Silicon Oxides" Dekker Encyclopedia of Chemical Processing, 2006, 1143.
7. D. B. Asay and S. H. Kim, "Evolution of the Adsorbed Water Layer Structure on Silicon Oxide at Room Temperature" J. Phys. Chem. B 2005, 109, 16760.
8. K. Strawhecker, D. B. Asay, J. P. McKinney, and S. H. Kim "Effects of Adsorbed Water Layer Structure on Adhesion Force of Silicon Oxide Nanoasperity Contact in Humid Ambiance" Tribol. Lett. 2005, 19, 17.
9. H. B. Nembhard, N. Acharya, M. Aktan, and S. H. Kim "Design Issues and Analysis of Experiments in Nanomanufacturing" Handbook of Industrial & Systems Engineering 2005, Chapter 17.
10. M. Leolukman and S. H. Kim "Effect of Rubbing-Induced Polymer Chain Alignment on Adhesion and Friction of Glassy Polystyrene Surfaces" Langmuir 2005, 21, 682.

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