Australian scientists have developed a knitting technique capable of producing electrically-conductive Spandex-carbon nanotube hybrid textiles at industrial scales. As described earlier this month in a paper published in ACS Nano, the stretchable fabrics "exhibit excellent performance" as sensors and artificial muscles. Potential applications include adjustable smart clothing, robotics, and medical devices.
At the core of the material is regular old Spandex, which is basically artificial super-rubber spun into fibers. In the process outlined in the paper, SPX filaments are coated with aerogel sheets of carbon nanotubes. Carbon nanotubes have the neat property of tunable electrical conductivity, and by tweaking the fabrication process, it's possible to create materials with electrical and mechanical properties that change as the fabric changes shape. Meet the bike shorts of the future.
"The coating method operates at room temperature, requires no solvents, and does not compromise textile production speeds," the Australian team reports. As such, the hybrid yarns are also pretty cheap to produce—a key requirement.
What makes the stuff really interesting is how it converts electricity into mechanical work. With an applied voltage, it's possible to get the textile to contract by as much as 33 percent as it heats up. The material then relaxes as the voltage is removed and it cools down. This mechanical power output maxes out at around 1.28 kW/kg, which, the paper notes, is well beyond what's offered by mammalian skeletal muscle. To demonstrate, the researchers used their new material to implement a knee brace, as below:
Another possible biomedical application is as a "lymph sleeve," a compression sleeve used to treat lymphedema, a common side effect of cancer treatments.
"The lymph sleeve, for example, will be developed using lightweight actuating fabric that will detect swelling and then respond by 'squeezing' the arm to enhance lymph flow," Javad Foroughi, the lead author of the new paper, told Physics World. "We are also investigating the possibility of employing it in artificial-heart muscles for positive support of the right ventricle."