High-tech yarn generates energy

‘Stretch for power’

MIAMI, Aug 26, (Agencies): Researchers in the United States and South Korea have invented a new kind of yarn that can generate electricity when it is stretched or twisted, said a study Thursday.

The material, called “twistron”, could be used to harvest energy from the motion of ocean waves, or from changes in temperature, said the report in the journal Science.

“The easiest way to think of twistron harvesters is, you have a piece of yarn, you stretch it, and out comes electricity,” said co-author Carter Haines, associate research professor at the University of Texas, Dallas.

The y6rn is built from carbon nanotubes, which are hollow cylinders of carbon 10,000 times smaller in diameter than a human hair, according to the report.

In order to generate electricity, the yarns must be either submerged in or coated with an ionically conducting material, or electrolyte, which can be as simple as a mixture of ordinary table salt and water.

“When you insert the carbon nanotube yarn into an electrolyte bath, the yarns are charged by the electrolyte itself,” said co-author Na Li, a research scientist at UT Dallas’s NanoTech Institute.

“No external battery, or voltage, is needed.”

The research is still at an early stage, and scientists caution that the technology is not meant for large-scale electricity projects, at least not yet.

Instead, lab experiments have shown that “a twistron yarn weighing less than a housefly could power a small LED, which lit up each time the yarn was stretched,” said the report in Science.

Another experiment showed that when sewn into a shirt, the yarns served as a self-powered breathing monitor.

“There is a lot of interest in using waste energy to power the Internet of Things, such as arrays of distributed sensors,” Li said.

“Twistron technology might be exploited for such applications where changing batteries is impractical.”

Other researchers involved with the project are affiliated with Hanyang University in South Korea.

The research was funded by the US Air Force, NASA, the Office of Naval Research, the Robert A. Welch Foundation, the Korea-US Air Force Cooperation Program and the Korean Ministry of Science.

An international team of scientists said in a study they had developed a stretchy yarn made of carbon nano- tubes — tiny strands of carbon atoms up to 10,000 times smaller than a hair — that produces electricity from a host of natural sources.

“The easiest way to think of twistron harvesters is, you have a piece of yarn, you stretch it, and out comes electricity,” said Carter Haines, a lead author of the study published in the journal Science.

The device, which exploits the ability of nanotubes to transfer spring-like motion into electrical energy, has numerous possible applications, according to the paper.

In the lab, tests showed that a yarn weighing less than a housefly could light up a small LED light.

When sewed into a t-shirt, it could power breathing sensors — like those used to monitor babies — using the stretch caused by the chest expanding at every inhalation.

The innovation could be used to power internet-connected devices and smart clothing, said the study’s senior author Ray Baughman, a professor at The University of Texas at Dallas.

“Electronic textiles are of major commercial interest, but how are you going to power them,” Baughman said in a statement. “Harvesting electrical energy from human motion is one strategy for eliminating the need for batteries,” he said.

But the twistron’s most compelling feature was the ability to operate in sea water and potentially harvest vast amounts of energy from the ocean, he added.

“The grander dream is to make a real difference in the energy economy of nations,” Baughman told the Thomson Reuters Foundation by phone.