Reprogrammable auxeticity in chiral multistable metamaterials

Auxeticity typically refers to materials that contract laterally under axial compression, a property extensively leveraged in metamaterials for energy absorption, vibration isolation, and shape morphing. In this work, we propose a class of multistable metamaterials that enable in-situ activation and deactivation of global auxeticity through a rotary bistable mechanism with chiral symmetry. By combining theoretical analysis, numerical simulations, and experimental validation, we elucidate the governing role of the chiral mechanism in its “open” and “close” states, which allows the building blocks to switch between counter-rotational and shear-dominant deformation modes under compression. Furthermore, we demonstrate that chiral multistable architectures deliver reprogrammable global buckling and snapping sequences under hydrostatic pressure. The approach here presented enables chiral multistable metamaterials with reprogrammable auxeticity, stiffness, snap-through instabilities, thereby opening avenues for the design of adaptive and multifunctional matter in soft robotics and fluidics.