Nature-derived highly tribopositive ϰ-carrageenan-agar composite-based fully biodegradable triboelectric nanogenerators

Abstract

Biodegradable triboelectric nanogenerators (TENGs) have been studied for powering biotransient electronics in past years. For stable powering, developing biodegradable materials which have high tribopositive properties as well as high biocompatibility is crucially required. Here, we investigate a nature-derived ϰ-carrageenan-agar (ϰC-Agar) composite as high-performing triboelectric friction material for biodegradable TENG. We found that the composite shows greatly enhanced electron-donating property. At an optimized ϰC concentration of 80 wt%, the surface potential at most 57.5% increases compared to bare materials. We validated that the enhancement was caused by increased charge trapping sites consisting of Ca2+ cations and sulfate ester groups in the composite. In addition, we found that the ϰC-Agar composite has high intrinsic biocompatibility as it shows high cell viability in MTT assay and subdermal implant causes little noticeable inflammation, contributed by the high hydrophilicity of the composite. We further demonstrate a fully biodegradable TENG using an optimized ϰC-Agar composite. Very thin (0.3 mm) and flexible our device generates high output root-mean-square (RMS) current of 0.45 mA·m−2 and output RMS power of 0.15 mW·m−2 at optimized impedance. Our work provides a basis for the development of high-performance biodegradable TENGs for self-powered transient electronics.