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[Image above] A scanning electron micrograph of coiled carbon nanotube yarns that can generate electrical energy when stretched or twisted. Credit:  University of Texas at Dallas 

An international research team led by scientists at the University of Texas at Dallas and Hanyang University in South Korea have fashioned carbon nanotubes into “twistron” yarns that can generate electrical energy when pulled, stretched, tugged, or twisted.

In a new proof-of-concept study published in Science, the scientists twist-spun carbon nanotubes into yarn, and then twisted the yarn so tightly that it wound itself into a twisted coil, making the yarn elastic.

When immersed or coated in an electrolyte solution, the twisted yarns can generate electricity all on their own—simply by harvesting tensile or torsional mechanical energy and electrochemically converting it into electrical energy.

Although they may not be suitable to weave the latest fashion trends, these carbon nanotube yarns are promising battery-free energy solutions that could eventually be used to harvest power from nearly anything that generates regular kinetic motion, including breathing chests and lapping ocean waves.

“Fundamentally, these yarns are supercapacitors,” Na Li, a research scientist at the NanoTech Institute and leading author of the study, says in a UT Dallas news release. “In a normal capacitor, you use energy—like from a battery—to add charges to the capacitor. But in our case, when you insert the carbon nanotube yarn into an electrolyte bath, the yarns are charged by the electrolyte itself. No external battery, or voltage, is needed.”

The carbon nanotube yarns can generate a small yet significant amount of energy, suggesting they could be used to power wearables or sensors for the Internet of Things, for example.

“Stretching the coiled twistron yarns 30 times a second generated 250 watts per kilogram of peak electrical power when normalized to the harvester’s weight,” Ray Baughman, director of UT Dallas’s NanoTech Institute and a corresponding author of the study, says in the release.

The paper, published in Science, is “Harvesting electrical energy from carbon nanotube yarn twist” (DOI: 10.1126/science.aam8771).

Watch this short Science video to learn more.

Credit: Science Magazine; YouTube