Enhancing Hydrophobicity of Starch for Biodegradable Material-Based Triboelectric Nanogenerators

Plastic pollution would be reduced by the use of sustainable, eco-friendly, and biodegradable devices. Starch is a readily available natural, edible, and biodegradable polymer. The strong hydrophilicity of starch hinders its use in the development of biodegradable triboelectric nanogenerators (TENGs), which must exhibit long-term stability. We enhanced the hydrophobicity of starch by introducing an edible Laver filler. A 1 wt % starch/Laver (SL) composite had a contact angle of 107°, which is far higher than that of pristine starch. We fabricated a fully packed SL-TENG using polycaprolactone (PCL) as the negative layer and edible gold leaf as the electrode. The PCL layer also served as the packaging layer, as it is stable in phosphate-buffered saline for 30 days. The 1 wt % SL-TENG exhibited 4- and 9-fold increased voltage and current outputs, respectively, compared to pristine starch. Finally, SL-TENG is utilized for biomechanical energy harvesting and for powering numerous electronics such as a calculator, stopwatch, wristwatch, and thermometer.