Eggshell membrane and expanded polytetrafluoroethylene piezoelectric-enhanced triboelectric bio-nanogenerators for energy harvesting

With the growing demand for wearable electronic devices, triboelectric nanogenerators (TENGs) provide an effective solution by harvesting human body motions and converting them into electricity. Tribomaterial is one key element for the output performance and application of TENGs. In this study, biomaterial eggshell membrane (ESM) was investigated for use as a piezoelectric-enhanced positive tribomaterial. ESM not only exhibits excellent piezoelectricity due to the amount of hydrogen bonds, but it is also biocompatible and pollution free. The piezoelectricities of raw eggshell membrane (RESM), heated eggshell membrane (HESM), and carbonized eggshell membrane (CESM) were analyzed and compared. Porous expanded polytetrafluoroethylene (ePTFE) was fabricated and used as a negative tribomaterial in the TENG due to its strong electron-acquisition ability. Pairing ESM with an ePTFE resulted in a novel piezoelectric-enhanced triboelectric bio-nanogenerator (P-TENG) with an excellent energy harvesting ability, high-efficiency output performance, and sensitive human motion monitoring. By comparing ePTFE paired with RESM, HESM, and CESM, the CESM/ePTFE P-TENG showed the best output performance due to CESM's piezoelectric enhancement. This bio-P-TENG as a wearable electric device has great potential in biomedical applications.