Silk and silk composite aerogel-based biocompatible triboelectric nanogenerators for efficient energy harvesting

Abstract

Triboelectric nanogenerators (TENGs) with high performance and biocompatibility are of demand for the development of novel medical devices and wearable electronics. Herein, a highly porous silk aerogel-based TENG (STENG) with high output performance was developed using silk fibroins extracted from silk cocoons. The silk aerogel made of 2% silk fibroin solution showed a nanofibrillated porous structure and the highest surface area, which contributed to the high triboelectric output performance of the STENG based on it. The rough surface and highly porous structure facilitated charge generation of the aerogels. The optimized STENG achieved an open circuit voltage of 52.8 V and a short circuit current of 5.2 μA, and a maximum power density of 0.37 W/m2 was reached on a 1 Mω external resistor. The STENG possesses high stability under different operation frequencies and in long term, and it could act as a power source for small electronics. Moreover, the excellent biocompatibility of silk aerogels to human cells makes the STENG possible to be used as implantable energy harvesters. In addition, because of its high tribopositivity, silk can be used as additives to fabricate composite aerogels. With an addition of 20% silk, the power of cellulose nanofibril-based TENGs improved by 3.1 times.