Carbon nanotube thread generates power from human movement
A new form of yarn which produces an electrical current when stretched could hold the key to powering the next generation of smart textiles, and open up exciting possibilities for the renewable energy market.
According to researchers from the University of Texas NanoTech Institute in Dallas, US, where the yarns were developed, the carbon nanotube “twistron” threads can be woven into clothing to generate electricity from human movement.
The potential for clothing being able to generate its own electricity overcomes many of the current hurdles faced by smart clothing and textiles manufacturers.
“Electronic textiles are of major commercial interest, but how are you going to power them?” Says Dr Ray Baughman, director of the University of Texas NanoTech Institute. “Harvesting electrical energy from human motion is one strategy for eliminating the need for batteries.”
Carbon nanotubes are hollow cylinders of carbon 10,000 times thinner than the diameter of a human hair.
To make the twistrons, the researchers first spun nanotubes into high-strength lightweight yarns. The elastic yarns acted as “super-capacitors” that stored energy when submerged in an electrically conducting solution, such as water and salt.
Twisting or stretching the yarn causes the stored energy to be released.
In laboratory tests the scientists showed that a twistron yarn weighing less than a housefly could power a small LED, which lit up each time the thread was stretched. When twistrons were sewn into a shirt, normal breathing by the wearer produced an electric signal.
Another demonstration, conducted on a South Korean beach, involved attaching a 10-centimetre long piece of yarn between a floating balloon and a sinker on the sea bed. With each incoming wave, the balloon rose and stretched the yarn up to 25 per cent to generate electricity.
“If our twistron harvesters could be made less expensively, they might ultimately be able to harvest the enormous amount of energy available from ocean waves. However, at present these harvesters are most suitable for powering sensors and sensor communications,” says Baughman.