Reprogrammable mechanical metamaterials with heterogeneous assembly of soft shell‐based voxels

Mechanical metamaterials are well studied to enable functions that are difficult to achieve in natural materials, in which reprogramming of specific underlying structures targeting different mechanical responses is particularly challenging. Herein, a heterogeneous voxel assembly-based 2D mechanical metamaterial is purposed, aiming at a reprogrammable design of the mechanical properties and shape-morphing simultaneously. In particular, each voxel is structured with a bistable soft shell and soft beams, which can be well controlled to achieve various desirable mechanical properties by a parameterized design method. The engineered metamaterial has a periodic arrangement of the voxel structures that can be transformed into an arbitrary aperiodic architecture with low geometrical frustration in the metamaterial plane by manipulating voxels, in which reprogrammable stiffness and Poisson's ratios, as well as deformation sequences and complex surface textures, can be achieved. In addition, the voxelated assembly has two modes allowing for fine or extensive tuning of the stiffness and the optional generation of 1D or 2D textures. Under this design paradigm, the programmability of multiple mechanical responses can support the development of more intelligent mechanical metamaterials with great potentials to soft robotics and active deformable devices.