4D Printing Auxetic Metamaterials with Tunable, Programmable, and Reconfigurable Mechanical Properties

Abstract Auxetic mechanical metamaterials, which expand transversally when axially stretched, are widely used in flexible electronics and aerospace. However, these chiral metamaterials suffer from three severe limitations as a typical auxetic metamaterials: narrow strain range, non‐tunable mechanical behaviors, and fixed properties after fabrication. In this work, 4D printing chiral metamaterials with tunable, programmable, and reconfigurable properties are developed. The deformation mode transforms from bending dominated to stretching dominated under large deformation, leading to the stress–deformation (σ–λ) behavior of the auxetic metamaterials similar to those of the biomaterials (“ J ”‐shaped), such as tissues or organs. The programmability and reconfigurability of the developed chiral metamaterials allow mechanical behavior to change between different biomaterials with high precision. Furthermore, scaffolds with personalized mechanical properties as well as configurations and metamaterials‐based light‐emitting diode integrated devices demonstrate potential applications in tissue engineering and programmable flexible electronics.