Wrinkling micropatterns regulated by a hard skin layer with a periodic stiffness distribution on a soft material

A wrinkling-based method is proposed to create various surface micropatterns regulated by a hardened skin layer with a periodic stiffness distribution on a soft material. It is shown that the surface patterns generated by this technique are controlled by three fundamental surface deformation modes that involve sinusoidal wrinkling, Euler buckling, and rigid rotation of the skin. Systematic experiments and a phase diagram validate the efficacy and robustness of the proposed method. (C) 2016 AIP Publishing LLC.