Researchers demonstrate new type of carbon nanotube fiber that captures mechanical energy

Nanotechnology researchers at the University of Texas at Dallas have created new carbon nanotube fibers that convert mechanical motion into electricity more efficiently than other material-based energy harvesters.

In a study published on January 26, natural energy, UT Dallas researchers and their collaborators describe improvements to a high-tech fiber they invented called “twist yarn,” which generates electricity when stretched or twisted. Their new versions are constructed like traditional wool or cotton yarns.

Twistron sewn into fabric can sense and collect human movement; when deployed in salt water, the volutes can capture energy from the motion of ocean waves; and the coils can even charge supercapacitors.

First described by UTD researchers in a Research published in 2017 in the magazine Science, twistrons are composed of carbon nanotubes (CNTs), which are hollow cylindrical carbon tubes 10,000 times smaller in diameter than a human hair. To create the helices, the nanotubes are twisted into lightweight, high-strength filaments or fibers, in which an electrolyte can also be incorporated.

Previous versions of twists were highly elastic, which the researchers achieved by creating so many twists that the coiled fibers resembled an over-twisted rubber band. Electricity is generated by coiled fibers by repeatedly stretching and releasing them, or by twisting and unscrewing them.

In the new study, the team didn’t twist the yarn to the point of winding it up. Instead, they intertwine three individual strands that pull into yarn carbon nanotubes yarn to form a single yarn, similar to the way conventional yarns are used in textiles—but with a different twist.

Dr Ray Baughman, director of the company, said: “The twine used in textiles is usually made of individual yarns that are twisted in one direction and then spun together in the opposite direction to create the final strand. This heterostructure provides stability against splintering.” The Alan G. MacDiarmid Institute of Nanotechnology at UT Dallas and the study’s corresponding author.

Baughman, Robert A. Welch Distinguished Chair of Chemistry in the School of Natural Sciences, said: “In contrast, our highest performing carbon nanotube layered twistrons are equally capable of twisting and pleating. — they are congruent, not heterojunction.” and Mathematics.

In tests with pleated CNT fibers, the researchers demonstrated an energy conversion efficiency of 17.4% for tensile (stretching) energy capture and 22.4% for torsion energy capture ( twisted). Previous versions of torsion coils achieved peak energy conversion efficiency of 7.6% for both torsion and drag energy capture.

“These helices have a higher power output per harvester weight over a wide frequency range—from 2 Hz to 120 Hz—than previously reported for any mechanical energy harvester,” says Baughman. material-based learning, no twists”.

Baughman says the improved performance of pleated twist yarns is a result of the yarn’s transverse compression when stretched or twisted. This process causes the layers of fabric to come into contact with each other in a way that affects the electrical properties of the yarn.

“Our material does something very unusual,” says Baughman. “When you stretch them, instead of becoming less dense, they become denser. This condensation pushes the carbon nanotubes closer together and contributes to their ability to capture energy. We have A large group of theorists and experimentalists are trying to understand more fully why we have achieved such good results.”

The researchers found that building yarns from three layers providing optimal performance.

The team conducted a number of proof-of-concept experiments using three-layer helices. In a demonstration, they simulated the generation of electricity waves by attaching a three-layer spiral between a balloon and the bottom of an aquarium filled with salt water. They also arranged multiple multi-layered twistrons into an array that weighed just 3.2 milligrams and continuously stretched them to charge a supercapacitor, which would then have enough power. energy to power five small light-emitting diodes, a digital clock, and a digital temperature/humidity sensor.

The team also sewed CNT threads into a cotton cloth, which was then wrapped around a person’s elbow. Electrical signals are generated when the person repeatedly bends their elbow, suggesting potential for using these fibers to sense and pick up on human movement.

The researchers have applied for a patent based on this technology.