Engineering reversible elasticity in ductile and brittle thin films supported by a plastic foil

Reversible deformation is a unique property of elastic materials. Here, we design and fabricate highly stretchable multilayered films by patterning Y-shaped motifs through films of non-elastic materials, e.g. plastics, metals, ceramics. By adjusting the geometry and density of the motif, as well as the thickness of the film(s), the effective spring constant of the engineered film(s) can be tuned. Three-dimensional bending of the patterned film(s) enables macroscopic stretchability and minimizes local film strain fields. The engineered films demonstrate no preferential direction of stretching and the proposed design is versatile. Furthermore our approach is compatible with thin-film processing. We demonstrate the Y-shaped motifs allow for the design of stretchable plastic foils coated with metallic and metal oxide conductors. We anticipate the patterned motifs can be scaled down to offer a wider range of elastic electronic materials to use in stretchable electronics and to create soft bioelectronics.