Nature-inspired helical piezoelectric hydrogels for energy harvesting and self-powered human-machine interfaces

Empowering hydrogels with self-powered capabilities addresses the limitations of conventional hydrogels that depend on external power. Among self-powered hydrogels, piezoelectric hydrogels (PHs) stand out for their minimal power consumption and exceptional wearability, making them ideal for wearable energy harvesting and self-powered sensing. However, enhancing the piezoelectric performance of current PHs often sacrifices flexibility due to the addition of stiffer materials, restricting their practical use. Here, we introduce an innovative selfpowered dual-network PH with 3D-interconnected cellulose and poly(vinylidene fluoride-trifluoroethylene) (C/P (VDF-TrFE)) microstructures, crafted using a co-solvent method. This dual-network PH offers an exceptional balance of self-powered capability, skin-like flexibility, high strength, and toughness, enabling structural deformation and nature-inspired 3D designs from helices to rings tailored for specific wearable applications. We showcase a helical PH device integrated with a pacemaker lead for cardiac energy harvesting and a smart PH ring functioning as a self-powered human-machine interface. This work presents a straightforward and effective approach to creating self-powered hydrogel devices with advanced 3D architectures for next-generation wearable bioelectronics.