Is there more than one stickiness criterion?

Abstract Adhesion between an elastic body and a smooth, rigid substrate can lead to large tensile stresses them. However, most macroscopic objects are microscopically rough, which strongly suppresses adhesion. A fierce debate has unfolded recently as whether local or global parameters determine the crossover small Here, we report simulations revealing that dependence of pull-off force F n on surface energy γ does not only have two regimes high low adhesion but up four regimes. They related contacts, at moment rupture consist (i) last individual Hertzian-shaped contact, in is linear , (ii) meso-scale, patches with super-linear scaling, (iii) many isolated contact extremely strong (iv) dominating largest patch, for stress no longer negligible compared maximum, microscopic stress. Regime be seen transition domain. It located near point where half per unit area conformal contact. criterion appears difficult grasp.