Elastomeric Ionic Hydrogel-Based Flexible Moisture-Electric Generator for Next-Generation Wearable Electronics

Rapid consumption of traditional energy resources creates utmost research interest in developing self-sufficient electrical devices to progress next-generation electronics to a level up. To address the global energy crisis, moisture-electric generators (MEGs) are proving to be an emerging technology in this field, capable of powering wearable electronics by harvesting energy from abundantly available ambient moisture without any requirement for external/additional energy. Recent advances in MEGs generally utilize an inorganic, metal, or petroleum-based polymeric material as an active material, which may produce sufficient current but lacks the flexibility and stretchability required for wearable electronics. Herein, we prepared an elastomer-based ionic hydrogel as an active material, and an MEG was fabricated by placing the ionic hydrogel on a PET sheet with two copper tapes on both sides of the hydrogel. The preparation of the hydrogel was thoroughly optimized and characterized in terms of spectroscopic analysis, swelling, water retention, and mechanical and rheological studies. The highly stretchable (350%) fabricated MEG is capable of producing a short-circuit current (J_SC) of 16.1 μA/cm², an open-circuit voltage (V_OC) of 0.24 V, and a power density of 3.86 μW/cm². The synergistic effect of the ion concentration gradient and the redox reaction on electrodes can be considered MEG's working principle. Apart from the current generation, this device is also used as a self-powered electronic sensor to monitor different physical activities by measuring breathing patterns. This prepared device is also capable of sensing the proximity of a hand. Therefore, our low-cost, easily fabricable, sustainable MEG device can be a potential aspirant for next-generation self-powered wearable electronics in healthcare applications.