The development of a friction-based wearable autonomous energy system is the aim of a new project being led by Heriot-Watt University’s Research Institute for Flexible Materials.

The team will use nanogenerators designed to capture and reuse the kinetic energy in clothing materials created as the wearer moves.

Professor George Stylios from Heriot-Watt’s School of Textiles and Design in the Scottish Borders is leading on the textile aspects of the project.

“As humans, we collectively expend a huge amount of energy as we move around so why not capture this and put it to good use?” he said “To do so would not only benefit the planet in our fight against climate change but also deliver ongoing convenience to people’s lives.

“The fabric type and mechanics, and most importantly the surface interaction of the fabric, is vital in enabling us to generate enough energy by the coupling effect of motion and nanotechnology to generate a renewable source of electricity.”

In the same way that static electricity is created, the scientists are looking to optimise the friction generated between two materials in order to generate a charge. They are developing a flexible fabric known as a triboelectric nanogenerator, or TENG, to harness and store this sustainable energy source.

Previous attempts to create fabric TENGs have failed largely due to them being unable to generate adequate power.

 “Our biggest challenge is increasing our power output in order to make this a viable option,” said Stylios. “Textile TENGs currently produce power in the microwatt to milliwatt range and we need to drastically increase the level of friction in order to achieve an output of hundreds of milliwatts, which is required to power most mobile devices.

“Our answer to this problem is to create an extremely efficient energy generation fabric material for use in every garment. We are looking to optimise friction and using advanced material processing techniques to produce surfaces that work on micron-sized fibres. This technology is safe to wear and use since the levels of current output are very low, posing no harm to the user. The focus would be in areas of maximum body contact such as in the side of elbows. 

“Once we have generated and stored this energy the question is how do we transfer it into mobile devices? We have a couple of ways for doing this. Firstly, we can store the electricity in a small polymer battery on the clothing itself, but my preference is the second option of directly transferring the electricity wirelessly, by simply carrying a phone in a pocket.”

The four-year project has received the backing of the main funding body for engineering and physical sciences research in the UK and Ireland, the Engineering and Physical Sciences Research Council (EPSRC) and the Science Foundation Ireland (SFI), which have awarded £1.9 million to advance the research.

It involves the University of Glasgow, the Institute of Technology Sligo, Tyndall National Institute and Heriot-Watt’s School of Textiles and Design. Each institution is contributing a diverse set of specialisms in areas such as tribology, materials chemistry, electronics and textiles.

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