Effect of nanoscale roughness on four different atomic force microscopy probes in aqueous solutions using adhesion force measurement

Abstract

Despite substantial theoretical approaches explaining the effect of nanoscale roughness (NR) on particle deposition, experiments are rarely performed. Fabricating the sophisticated rough surfaces and obtaining the experimental data for interaction between the colloids and surfaces are crucial to understand colloidal adsorption onto the rough surfaces. We investigated the adhesion of different particle types of atomic force microscope (AFM) probes (different shapes, i.e., sphere and plateau; diameters, i.e., 2 μm–15 μm) onto smooth and rough fabricated surfaces. We successfully fabricated well-organized rough surfaces on Silicon (Si) using colloidal lithography and metal-assisted chemical etching using a cylindrical shape of constant nanoscale height and diameter. The properties of roughness (i.e., height, diameter, and fraction) were quantitatively analyzed, and the corresponding. The force-distance curves measured with the AFM revealed that, for the four types of probes, contact area varied with the surface roughness, and their adhesion forces differed accordingly. Expanding the contact area tended to increase the repulsive force possibly because of the hydration force. This study effectively devised a simplified experimental system that explains the influence of NR on particle deposition using previous theoretical data. The findings should be considered in designing NR for subsequent colloidal deposition.