Surface charge-enhanced cellulose nanocrystal/polyvinyl alcohol/carbon nanotube composite for high-efficiency hydrovoltaic power generation and durable wearable health monitoring sensor

Artikel i vetenskaplig tidskrift, 2025

Hydrovoltaic energy harvesting — extracting electricity from water evaporation and moisture gradients — is emerging as a promising renewable power source for self-sustained devices. Here, we report a highly flexible and durable hydrovoltaic energy generator (HVEG) based on a composite of surface charge-enhanced sulfonated cellulose nanocrystals (CNCs), polyvinyl alcohol (PVA), and carbon nanotubes (CNTs) coated on mulberry paper (MP). The negatively charged CNCs enhance electric double layer (EDL) formation, while CNTs enable efficient charge collection, and PVA improves mechanical stability. The device achieves an open-circuit voltage of 300–350 mV, a short-circuit current of ∼30 µA under ambient condition, which was further enhanced to 550 mV/ 60 µA, with a high volumetric power density of 73.5 µW cm⁻³ under external stimulation such as mechanical rubbing. The HVEG also demonstrates stable power generation performance even after repeated mechanical deformation, high-velocity water splashing (7.5 m/s), and prolonged water immersion. A series connection of multiple devices successfully powers LEDs and digital electronics. Furthermore, the device operates as a self-powered wearable sensor, detecting breathing, coughing, speaking, and physical activity with a rapid response time (<2 s) and sensitivity exceeding 40 %. Our work demonstrates a high-performance, self-sustained energy platform for next-generation wearable health monitoring applications.