Sustainable Triboelectric Nanogenerator from Abalone Shell Powder for Self-Powered Humidity Sensing

Self-powered sensors are critically important for IoT, yet most rely on synthetic polymers that lack environmental sustainability. This work presents a triboelectric nanogenerator (TENG) made from marine biowaste which operates as both an energy generator and humidity sensor. Abalone shell powder (ASP) majorly composed of calcium carbonate (CaCO₃) was used as its tribopositive layer in combination with polytetrafluoroethylene (PTFE) as tribonegative layer. The developed ASP-TENG device generated 410 V peak to peak open-circuit voltage (V_OC) and 2.79 W·m^-2 peak power density at an operating frequency of 4 Hz. These obtained results match or surpass existing biowaste-based TENGs. ASP-TENG efficiently worked as a self-powered humidity sensor because its output voltage decreased steadily from 410 V to 176 V in response to an increase in relative humidity (%RH) from 40% to 80% (decreases of 5.8 V for every 1%RH). The triboelectric charges become screened by water molecules that adsorb onto the porous CaCO₃ surface which leads to faster leakage current. This work demonstrates a sustainable method to create TENGs with multiple functions while developing environmentally friendly sensing systems for environmental tracking and sustainable energy harvesting.