Surface Morphing of Geometrically Patterned Active Skins

Abstract

Nature is ripe with biological organisms that can interact with its surroundings to continuously morph their surface texture. Many attempts have been made to optimize artificial surfaces depending on operational needs; however, most of these architected materials only focus on enhancing a specific material property or functionality. This study introduces a new class of instability-induced morphable structures, herein referred to as “Active Skins”, which enables on-demand, reversible, surface morphing through buckling-induced feature deployment. By taking advantage of a preconceived auxetic unit cell geometrical design, mechanical instabilities were introduced to facilitate rapid out-of-plane deformations when in-plane strains are applied. Here, these notches were introduced at judiciously chosen locations in an array of unit cells to elicit unique patterns of out-of-plane deformations to pave way for controlling bulk Active Skin behavior. These purposefully designed imperfections were employed for selectively actuating them for applications ranging from camouflage to surface morphing to soft robotic grippers.