A hydrogel-based energy harvester with broad bandwidth driven by ambient vibrations

This paper describes a hydrogel-based energy harvester (EH) which efficiently scavenge electrical energy from environmental vibration. The working mechanism of the proposed EH is based on the concept of an electrical double layer capacitor. A hydrogel drop is placed between two parallel conductive plates. External force applied to the plate causes the shape change of the hydrogel drop and the periodic deformation of the hydrogel generates electrical power. Compared with previously reported water droplet-based EHs, the hydrogel-based EH allows a wide bandwidth. It also provides a long-term stability in power generation. In the feasibility experiments, a broad vibration range of 0–70 Hz and an average output voltage of ∼100 mV are achieved with a hydrogel drop. Further increase of the power can be expected by the use of series of hydrogel drops.