Triboelectric nanogenerator shows promise for wearables

Developed by a team at Dongguk University-Seoul, the device can stretch up to 375 per cent of its original size and withstand mechanical deformations, making it suitable for wearable electronics. 

Triboelectric nanogenerators (TENGs) convert mechanical energy such as body movement to electrical energy and can be used to power wearables instead of using batteries. 

Most TENGs used in wearable applications incorporate a triboelectric material attached to an electrode. However, one of the challenges has been finding flexible electrode materials that can move seamlessly with the human body.

Now, a research team led by Professor Jung Inn Sohn has developed a gel polymer electrode-based triboelectric nanogenerator (GPE-TENG) that is stretchable, semi-transparent, and durable. The team’s findings are detailed here in the Chemical Engineering Journal.

“We report an in-situ curing strategy to develop a stretchable, semi-transparent, and durable GPE-TENG through enhanced interfacial bonding between the ionic polymer gel and ecoflex layers,” Prof. Sohn said in a statement.

To fabricate the device, the researchers poured a gel mixture of polyethylene oxide (PEO) and lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) into an ecoflex mould. The gel is spread evenly and then covered with another ecoflex layer. A copper wire is attached to the gel for electrical connection, and the assembly is cured at 70°C for 12 hours, allowing the gel to bond strongly with the ecoflex layers.

According to the team, the result is a durable, flexible, and semi-transparent device that generates electrical signals when tapped or stretched, delivering a peak power of 0.36W/m² at a load of 15MΩ. In tests, the device stretched up to 375 per cent of its original size without damage and could withstand two months of bending, twisting, folding, and stretching without any signs of delamination or loss of electrical performance.

The team believes its GPE-TENG could enable wearable devices that track joint activity for rehabilitation or act as a biometric system in clothing, allowing users to unlock smart doors or lockers.

“This work could revolutionise wearable technology by developing sustainable and flexible electronic devices with promising applications in human healthcare, rehabilitation, security systems, and secure biometric authentication systems,” said Prof. Sohn.