Edible rice paper-based multifunctional humidity sensor powered by triboelectricity

Electronic wastes are causing unadorned burden on our environment due to the use of hazardous materials therefore, using naturally available green materials is necessary for sustainable and eco-friendly future. Biowastes can be used as functional materials of advanced electronic devices owing to their biocompatibility, low cost, and abundant availability. In this study, we have explored the multifunctional humidity sensitive response of a cellulose enriched edible rice paper (CERP). Presence of hydrophilic functional groups and highly porous surface of CERP made it a highly suitable sensing material for adsorbing/desorbing water molecules over a full relative humidity (RH) sensing range (0–100 %RH). Fast response/recovery times (5/16 s) were recorded along with a high sensitivity of 97%. CERP was also used as the electropositive layer of a triboelectric nanogenerator (TENG) for harvesting energy, making it a self-powered humidity sensor. High performance results were obtained including output voltage (162 V), output current (2 μA), and power density (3 μW/cm2), respectively. Electrical energy produced by TENG was enough to charge 3 commercial capacitors (1 μF, 4.7 μF, and 10 μF) and light 30 green LEDs. Obtained results were highly stable (1500 s) and repeatable with a long lifetime (3 months).