Ridge localizations and networks in thin films compressed by the incremental release of a large equi-biaxial pre-stretch in the substrate.

Two-dimensional ridge structures are induced by equi-biaxial compression with large equi-biaxial pre-stretch in a thin film by using a micro-fluidics technique. Whereas wrinkles tend to be uniformly distributed, ridges are localized. The wrinkle-to-ridge transition is unstable (subcritical), resulting in large amplitude changes. The nature and morphology of the ridges is studied and quantified by experiments and numerical simulations.