A Highly Multi-Stable Meta-Structure via Anisotropy for Large and Reversible Shape Transformation.

Shape transformation offers the possibility of realizing devices whose 3D shape can be altered to adapt to different environments. Many applications would profit from reversible and actively controllable shape transformation together with a self-locking capability. Solutions that combine such properties are rare. Here, a novel class of meta-structures that can tackle this challenge is presented thanks to multi-stability. Results demonstrate that the multi-stability of the meta-structure is strictly tied to the use of highly anisotropic materials. The design rules that enable large-shape transformation, programmability, and self-locking are derived, and it is proven that the shapes can be actively controlled and harnessed to realize inchworm-inspired locomotion by strategically actuating the meta-structure. This study provides routes toward novel shape adaptive lightweight structures where a metamaterial-inspired assembly of anisotropic components leads to an unforeseen combination of properties, with potential applications in reconfigurable space structures, building facades, antennas, lenses, and soft robots.