How This Yarn Converts Movement Into Electricity When Stretched

We're getting closer to clothing being able to power wearable gadgets and smart technology. Scientists have been able to intertwine carbon nanotubes with yarn, and when expanded, can produce electricity.


May 21 2019, Updated 2:54 p.m. ET

While batteries and superconductors are trying to improve wearable technology, imagine if the clothing we wore could power these gadgets? To begin with, when we move around, we’re already creating kinetic energy. Although, of course, it’s been hard to transfer that into something useful; until now. Scientists from the University of Texas at Dallas have been developing a yarn that’s created from carbon nanotubes, which may be able to generate electricity simply from being stretched.

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In order to create this process, the yarn is twisted into elastic coils, which are called twistron harvesters. When stretched out, they’re able to generate electricity. With the addition of carbon nanotubes, these are able to store that energy and could fuel wearable gear. For example, these products could be smartwatches, activity trackers, or wearable cameras.

This new process has been a long time coming for Ray Baughman, a researcher from the university that’s been working on transferring kinetic energy to usable electricity since 1980. “We figured out that if you can use electrical energy to drive an artificial muscle to produce mechanical energy, maybe it’s possible to run it in reverse — and harvest mechanical energy as electricity,” Baughman told Digital Trends. “For all the years since then, I’ve failed to make this work. Now that’s changed.”

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With this breakthrough, additional voltage is no longer needed -- carbon nanotubes weaved together with strings of yarn are now able to power devices. Just one piece, when stretched out, could temporarily power on an LED. That means when many more pieces of yarn are put together, they could power devices by walking, running, or even just breathing.

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These twistron harvesters were also tested in ocean waves, which could be another source of renewable energy. According to Ars Technica, these scientists tested a piece of yarn in a salt solution that was similar to the ocean. While they were able to reach 250 watts per kilogram when the yarn was pulled at maximum strength, they were still able to output up to 90 watts per kilogram when the salt expanded the coils.

Unfortunately, there’s a few drawbacks to carbon nanotubes that prevents us from immediately jumping into the technology. Most importantly, it’s expensive to make. Carbon itself is cheap and costs continue to fall, but not when needing to create a large amount of twistron harvesters. Something as big as powering a house or charging a car battery wouldn’t be feasible at this time.

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Another problem is corrosion when being placed in the ocean. When testing the product off the coast of South Korea, a platinum electrode was added to keep this from happening. This would further add into the cost as the metal is rare. Efficiency is also a problem, as the string of yarn only expanded by 25 percent when taking on the ocean current.

Overall, there’s a lot of potential for clothes to be equipped with carbon nanotubes that create their own source of power. Now that scientists have figured out how to generate electricity without any external battery or voltage power, it’s now just a matter of time before it becomes cheaper and more efficient.

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