A Kirigami-Driven Stretchable Paper-Based Hydrovoltaic Electricity Generator

Hydrovoltaic electricity generator (HEG), which converts thermal energy from water evaporation into electrical energy, offers a promising solution for sustainable, low-power applications such as remote sensors and wearable flexible electronics. However, current HEG suffers from poor deformation adaptability due to its reliance on the rigid ion transport interfaces of hydrovoltaic materials for electrokinetic effects, limiting its potential in wearable electronics. Herein, a stretchable paper-based hydrovoltaic electricity generator (SP-HEG) is developed by laser-cutting an optimized kirigami pattern on paper functionalized with carbon black. The SP-HEG can stretch up to 200% without compromising its electrical output (open-circuit voltage of 1.2 V and short-circuit current of 6.0 µA), as mechanical stress is evenly distributed and stable ion transport interfaces are maintained on the kirigami patterns. Moreover, the SP-HEG can be used as a wearable energy supply device and self-powered sweat sensor, with the advantages of stable output unaffected by deformation, sustainable power generation, and environmental friendliness. This study opens up a novel strategy to design deformable energy harvesters, broadening the potential applications of hydrovoltaic power generators in the wearable field.