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 self-powered 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.