Textile Insight

magine wearing a shirt that can generate electricity to power a sensor just by breathing, using energy harvested by the fabric! Although numerous energy harvesters have been investigated over time, no other reported harvester can provide the high electrical power output of textiles made using the new "Twistron" yarn. Research scientists at the Alan G. MacDiarmid NanoTech Institute at the University of Texas Dallas, in collaboration with Hanyang University in South Korea and other key teammates, showed that normal breathing and human motion can stretch the Twistron yarns woven into a shirt, and generate electricity, eliminating the need for batteries. "Harvesting electrical energy from human motion is our strategy for elimi- nating the need for batteries," explained Dr. Ray Baughman, Director at the NanoTech Institute, "Our yarns when stretched produce more than a hundred times higher electrical power per weight, when compared to other weave-able fibers currently being studied." Twistron yarns are constructed from carbon nano- tubes (CNT), which are hollow cylinders of carbon 10,000 times smaller than a human hair. The research- ers first twist-spun the nanotubes into high-strength, lightweight yarns. In order to generate electricity, the yarns can be either submerged in an electrolyte bath that contains ordinary table salt mixed in water, or coated with a solid ionic-conducting polymer that separates two twistron harvesters. Through the process of twist-spinning, coiled CNT yarns are made that are highly elastic. When stretched, one kilogram (2.2 pounds) of Twistron yarn can generate a peak electrical power of 250 watts, without requiring an external bias voltage. The Twistron yarns in textiles serve as super-capacitors to store energy. In a normal capacitor, a source of power such a battery is needed in order to add charges to the capacitor. However, in the UT Dallas research, the CNT yarn becomes charged through the electrolyte bath itself, with no external battery or voltage required. When a garment made from this CNT harvester yarn is worn, any movement, stretch, or twist of the yarn causes the volume of the CNT yarn to decrease. This brings the electric charges on the yarn closer together, increasing the voltage of the yarn supercapacitor, thus enabling the harvesting of electricity. According to Dr. Carter Haines, associate research professor in the NanoTech Institute at UT Dallas, "the easiest way to think of 'Twistron' harvesters is — you have a piece of yarn and when you stretch it, out comes electricity!" Future Goals for "Twistron" Yarns Lab tests on a woven shirt made with CNT Twistron yarns have shown that even normal breathing causes the stretched yarn to generate an electrical signal, demonstrating the yarn's potential as a self-powered respiration sensor in apparel. Although initial tests have proven successful, Baughman says that the research team is at least two years away from Twistron yarns being made available commercially for performance clothing. In the future, the "Twistron" technology could be used for applications where changing batteries are impractical. Going forward, the research team has even bigger plans for UT Dallas' CNT "Twistron" harvesters. In a broader vision, Baughman states, "We also want to show that the 'Twistron' yarns can economically harvest the enormous energy in ocean waves, which is much more complex." O EDUCATION | UNIVERSITY OF TEXAS, DALLAS Batteries Not Required New Energy-Harvesting Yarns Generate Electricity in Textiles. By Kathlyn Swantko For More Information Contact Dr. Ray Baughman, Research Scientist-Faculty- Natural Sciences & Mathematics for more information. Ray.Baughman@utdal- las.edu, (972)883-6530. Kathlyn Swantko, president of the FabricLink Network, created TheTechnicalCenter.com for Industry networking and marketing of specialty textiles, and FabricLink.com for consumer education involving everything fabric. 48 • Textile Insight ~ January/February 2018 textileinsight.com I Scanned by an electron microscope, a coiled CNT yarn created at the University Texas at Dallas generates electrical energy when stretched or twisted. FabricLink.com TheTechnicalCenter.com "We have been using the FabricLink Network for over 10 years and it has consistently been one the top digital drivers to our site, and a great source of information for trade and consumers alike." Lisa Hardy North America Marketing Manager Teflon™ textile finishes, Teflon™ fabric protector, The Chemours Company Why clients are excited about the benefits of The FabricLink Network Partnership Opportunities: Kristi Rummel kristi@rummelmedia.com 608.435.6220 Editorial Opportunities: Kathy Swantko kgswantko@fabricklink.com 818.345.7501 How will they find you, if you're not there? The FabricLink Network THE Networking / Education Search Engine for ALL Things Textile Related!

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