A transparent silk-fibroin-based triboelectric microgenerator for airflow energy harvesting

We present a new transparent high-performance triboelectric microgenerator (TEMG) based on an emerging material, silk fibroin. Silk fibroin has a strong ability to lose electrons and occupies a top-level positive position in the triboelectric series. It thus significantly contributes to the performance enhancement of TEMG. To efficiently harvest energy from airflow, a channel-shaped TEMG was developed. A cube-shaped microstructure array was fabricated atop the other triboelectric pair, in our case PDMS, by casting against a 3D printed mold. Compared with flat surface, this design allows for a 2.5-fold increase of TEMG's output was realized. The systematic investigation of the electrical performance of TEMG showed that a power of 162 µW was achieved with a matched load of 8 MΩ. A corresponding power density of 864 W/m2 was achieved. This TEMG has outstanding powering ability, and is able to charge a 1 µF and a 10 µF capacitors to 1 V within 3.4 s and 15.7 s, respectively. Finally, the TEMG can be successfully used to deliver power to a 6-bit liquid crystal display (LCD) and 17 light emitting diodes (LEDs), respectively, without any external circuit.