Electricity-generating yarns

What if the shirt a patient wears could monitor breathing with no special power-driven applications—because the yarn it’s made of produces electricity? A research team led by scientists at the University of Texas at Dallas and Hanyang University in South Korea are developing these high-tech yarns.

The twistron yarns create electricity when twisted and stretched. Constructed from carbon nanotubes, the hollow cylinders of carbon  are 10,000 times smaller in diameter than a human hair. They’re twist-spun into high-strength, lightweight yarns to the point that they become highly elastic and coil like an over-twisted rubber band.

The yarns are then submerged in or coated with an ionically conducting material, or electrolyte, which can even be a mixture of table salt and water. This turns the yarn into a supercapacitor, charged by the electrolyte. No external battery or voltage is needed.

When twisted or stretched, the volume of the carbon nanotube yarn decreases, bringing the electric charges on the yarn closer together and increasing their energy and the voltage associated with the charge stored in the yarn, allowing the harvesting of electricity. In the case of apparel that monitors respiration, normal breathing stretched the yarn and generated an electrical signal.

For more information, visit www.utdallas.edu.