Capillary effect can be trivial in gecko adhesion
The present study is motivated by two classes of seemingly contradicting experiments on the effect of humidity or the capillary effect on adhesion. While one class of experiments suggests strong effect of humidity in gecko adhesion, those on micromachined surfaces indicate that the adhesion energy remains constant up to a relative humidity of 60–70% even for hydrophilic surfaces. To resolve this apparent paradox, we perform numerical simulations of the vertical peeling of a spatula pad adhered to a rough surface with periodic attachment sites.
