Surface roughness and hydrodynamic boundary slip of a Newtonian fluid in a completely wetting system

The hydrodynamic drainage force on a borosilicate glass sphere approaching a wall (silicon wafer) perpendicularly in a viscous liquid was measured using an atomic force microscope. The deformation of the microsphere in contact with the substrate was estimated using Johnson-Kendall-Roberts theory to be less than 0.1 nm. Aqueous solutions of sucrose of varying concentration whose temperature has been equilibrated at 20°C before each measurement were used as Newtonian viscous fluids. The experimental results were compared to the existing theoretical models.