Reprogrammable Soft Pneumatic Metamaterials with Multimodal Twisting and Tunable Multistability

Abstract

Energy landscape and deformation modes endow soft pneumatic metamaterials with specific functionalities encoded by design. Their ability to perform tasks beyond their as‐designed functions, however, is currently limited by the invariant nature of their properties, unalterable post‐fabrication. Herein, a modular strategy for soft pneumatic materials is introduced to reprogram both their energy landscape and deformation modes, enabling in‐situ tunable multistability with a plurality of deformation modes, including unprecedented multistable twisting. Two empowering features are sculpted into their architecture. The first is the insertion of narrow grooves, allowing the selective installation of modular stoppers initiating contact against mating elements and enabling multiple deformation modes. The second is the carefully tailored unit cell asymmetry, resulting in twisting bistability emanating from the building block and accumulating through tessellation. The stopper length tunability is investigated to initiate contact either prior to or during snap‐through for reprogrammable multistability, and both bistability and monostability are experimentally demonstrated in a single pneumatic actuator. Furthermore, the modular strategy for reprogrammable contact is leveraged to realize a soft robotic arm switching between diverse trajectories beyond those sealed by design, hence demonstrating the remarkable versatility this class of soft pneumatic metamaterials can offer to attain reprogrammable multistability and multimodality.