Programmable 3D Self‐Folding Structures with Strain Engineering

Abstract

Self‐assembly of three‐dimensional (3D) structures, through bending, twisting, folding, and buckling, has garnered broad interest among physicists, mathematicians, chemists, and biologists. Herein strain engineering and geometric frustration as an on‐demand strategy for fabricating spontaneous rolling "origami" structures with programmable multistability across multiple length scales are exploited. Through experiments, theory, and finite element simulations, it is demonstrated that a strain‐engineered bilayer structure can make a transition from a monostable, doubly curved shape to a neutrally stable, developable configuration, depending on a dimensionless parameter that is determined through the plate's geometry and misfit strain. In addition, the doubly curved region near the edge can play a significant role in deciding the final bending direction of the strained bilayer due to edge effects. A strain‐engineering approach is further proposed to generate various 3D structures by programming the geometry, misfit strain, and mechanical properties of the bilayer units, for instance, a self‐folding buckyball structure. These design principles have promising broad applications in constructing self‐deploying, stimuli‐responsible, and multifunctional devices across multiple length scales.