In a study published in the journal Science, researchers from institutions in the United States, South Korea, and China described the development of “twistron” yarns, which are essentially pieces of yarn that produce electricity when they are twisted or stretched.
The scientists performed several demonstrations utilizing the new material. They showed that a twistron yarn weighing less than a housefly could power a small LED, which lit up each time the yarn was stretched.
They sewed twistron harvesters into a shirt. Normal breathing stretched the yarn and generated an electrical signal, demonstrating its potential as a self-powered respiration monitor. There is a lot of interest in electronic textiles. The idea of powering them just from human motion instead of batteries is very appealing.
Another demonstration attached a 4-inch piece of yarn between a balloon and a sinker that rested on a seabed. Every time a wave came in, the balloon would rise, stretching the yarn and generating measurable electricity.
The twistron yarn is made from carbon nanotubes, which are hollow cylinders of carbon 10,000 times thinner than a human hair. The researchers twist and spin nanotubes into high-strength, lightweight yarns. To generate electricity, the yarns are either submerged in or coated with an ionically conducting material or electrolyte, which can as simple as salty water.
The studies used very small amounts of twistron yarn, but the researchers note that the performance is scalable by increasing twistron diameter and operating many yarns in parallel. If twistron harvesters can be made cheaply enough, they may have a wide range of applications such as those suggested by the early experiments. These new energy harvesters are an exciting new twist on electricity.
Photo courtesy of the University of Texas at Dallas.