Agarose Hydrogel-Based Power Source: Electrode Potential Engineering and Flow System Integration for Enhanced and Sustained Performance

Inspired by the electrical discharge mechanism of electric fish, we report a bio-inspired power source based on agarose hydrogels. The device generates electrical energy by exploiting ion concentration gradients across high- and low-salinity hydrogels, in combination with polyelectrolyte membrane gels exhibiting ion selectivity based on Donnan exclusion. Systematic optimization of hydrogel composition identified optimal ion concentrations and agarose content that balance energy output and mechanical stability. To further enhance performance, asymmetric redox pairs—ferrocyanide/ferricyanide at the anode and vanadium oxide at the cathode—were introduced, boosting both voltage and current outputs. Additionally, a continuous flow system was incorporated to replenish ionic gradients, addressing limitations from ion gradient depletion during extended operation. Simulations and experimental results confirmed that the flow-assisted configuration maintained stable ion distributions, enabling sustained power output over time. This work demonstrates a safe, scalable, and environmentally friendly platform for water-based energy harvesting, with potential applications in bio-interfacing and soft energy devices.