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Optimal Roughness For Minimal Adhesion, Nancy Burnham, D-L Liu, J Martin

Nancy A. Burnham

Roughness has a significant affect on adhesion. The authors used a single-asperity model to describe a smooth tip in contact with a rough surface and predicted that an optimal size of asperity yields a minimum of adhesion. Experimentally, adhesive forces on silicon wafers with varying roughness were measured using atomic-force-microscopy cantilevers with varying tip radii. It was found that minima do exist, and for all tip radii, the adhesion falls significantly for roughness greater than 1–2nm and drops at higher roughness for larger tips. This work should help minimize stiction in microelectromechanical systems and progress the understanding of nanoscale-contact mechanics.