Octopus tentacles inspired triboelectric nanogenerators for harvesting mechanical energy from highly wetted surface

It is difficult for triboelectric nanogenerators (TENG) to harvest energy with high humidity environments, due to the screening effect of water. The resistance of TENG with atmosphere humidity has been studied by many previous works, while the energy generation of TENG on highly wetted or even water-bearing surface has not been thoroughly studied. Hence, we propose an octopus tentacle inspired micro patterns on the interface of TENG, which can provide two kinds of functions. The honeycomb-shaped micro patterns on tribo-electrification interface can maintain the energy generation on highly wetted condition and the similar patterns on the hydrogel surface can also achieve good adhesive capability on water-bearing substrates. The contact interface with honeycomb-shaped micro patterns can facilitate the water drainage during the pressing motion, which can increase the effective contact area for electrification. The open-circuit voltage (Voc) of the TENG with patterned tribo surface can reach 78 V on highly wetted surface, which is two times higher than that of a planar device. On the other hand, the similar honeycomb-shaped micro patterns have been applied on the surface of tough PA hydrogel. Accordingly, a hydrogel based TENG with repeatable adhesive capability is prepared, which allows TENG device to be adhered on the water-bearing substrate and harvest water wave energy. The demonstrated designed concept of this honeycomb-shaped micro patterns interface has excellent applicability in water-bearing environment and water wave energy harvesting process, enhancing device usability and promoting its practical applications.