Many groups are developing energy-producing “smart fabrics,” a technology too complex to scale up for commercial use. But scientists have developed a simple method for embroidering electric generators on ordinary fabric. The new technique is being developed at North Carolina State University.

It contains a special thread made of polyurethane coated copper wire. This thread is processed on the basis of ordinary cotton fabric or any other material. But in the area where the yarn is attached, the cotton is covered with a fabric made from a synthetic polymer called PTFE (polytetrafluoroethylene). There is a small gap between the PTFE and the copper wires. At the final stage, a protective layer of ordinary cotton thread is embroidered on the copper wire thread.

As the wearer moves, the wires and PTFE come into contact with each other and come out of contact. When they collide, electrons are transferred between them, creating an electric current.

This phenomenon is known as the triboelectric effect and is responsible for the static charge created when you brush your hair. Small devices that use this effect to generate useful electricity are called triboelectric nanogenerators (TNGs).

Embroidered TENs are inexpensive to use and have been found to retain their function after multiple wash cycles.

“Our technique uses embroidery, which is pretty simple – our threads can be sewn directly to fabric,” says the developer. “You don’t need to think about wearables when producing fabric. After the garment is made, you can integrate the energy-generating threads.”