Controlling Adhesion Force by Means of Nanoscale Surface Roughness

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• 作者：Shivaprakash N. Ramakrishna ; Lucy Y. Clasohm ; Akshata Rao ; Nicholas D. Spencer
• 刊名：Langmuir
• 出版年：2011
• 出版时间：August 16, 2011
• 年：2011
• 卷：27
• 期：16
• 页码：9972-9978
• 全文大小：926K
• 年卷期：v.27,no.16(August 16, 2011)
• ISSN：1520-5827

文摘

Control of adhesion is a crucial aspect in the design of microelectromechanical and nanoelectromechanical devices. To understand the dependence of adhesion on nanometer-scale surface roughness, a roughness gradient has been employed. Monomodal roughness gradients were fabricated by means of silica nanoparticles (diameter 12 nm) to produce substrates with varying nanoparticle density. Pull-off force measurements on the gradients were performed using (polyethylene) colloidal-probe microscopy under perfluorodecalin, in order to restrict interactions to van der Waals forces. The influence of normal load on pull-off forces was studied and the measured forces compared with existing Hamaker-approximation-based models. We observe that adhesion force reaches a minimum value at an optimum particle density on the gradient sample, where the mean particle spacing becomes comparable with the diameter of the contact area with the polyethylene sphere. We also observe that the effect on adhesion of increasing the normal load depends on the roughness of the surface.