Energy harvesting by ambient humidity variation with continuous milliampere current output and energy storage†
A hygroelectric generator (HEG) is an energy harvesting technology that utilises ambient moisture as the energy source. However, this technology is currently hampered by a low current output and the need for an external energy storage device. In this study, a novel type of HEG with energy storage and high current output owing to a liquid-based cell structure called hygroelectric cell (HEC) was developed. The HEC could generate a peak-to-peak voltage of 42 mV and short-circuit current of 5 mA at maximum by humidity variation between 30–90% RH. In addition, the basic theories underlying the HEC were established and verified by experiments.