Multistable bioinspired origami with reprogrammable self-folding

Abstract

Origami has emerged as a design paradigm to realize morphing structures with rich kinematic and mechanical properties. Biological examples augment the potential design space by suggesting intriguing routes for achieving self-folding from architected materials. We introduce a class of multistable self-folding origami adaptable after fabrication inspired by the earwig wing. This is achieved by designing bilayer creases that display anisotropic shrinkage in response to external stimulation, enabling a mechanism for prestrain adaptation. We establish a bilayer model for stretchable straight and trapezoidal (β) creases to generate bistable origami structures. We adapt the topology of the structure’s energy landscapes by tuning the fold prestrain level as a function of the stimulation time. The proposed method and model allows for converting flat sheets with arranged facets and prestrained mountain-valley creases into self-folding multistable structures. Introducing multistability from self-folding avoids ambiguous folding branches present in the rich configuration space at the flat state. The obtained crease prestrain programming is leveraged to manufacture a biomimetic earwig wing featuring the complex crease pattern, structural stability and rapid closure of the biological counterpart. The presented method provides a route for encoding prestrain in self-folding origami, the multistability of which is adaptable after fabrication.