Engineering news
A new study reported in the journal Nano Letters described work at the Brown School of Engineering Lab, by engineer Matteo Pasquali. His team sewed nanotube fibres into athletic wear to monitor the heart rate, and take a continuous electrocardiogram of the wearer.
The fibres are just as conductive as metal wires, but less likely to break during motion, more comfortable – and washable. They are also better than a standard chest-strap monitor at taking live measurements during experiments.
“The shirt has to be snug against the chest,” said Rice graduate student Lauren Taylor, lead author of the study. “In future studies, we will focus on using denser patches of carbon nanotube threads so there’s more surface area to contact the skin.”
The fibres provided steady electrical contact with the wearer’s skin, and served as electrodes to which Bluetooth transmitters could be connected to relay data to a smartphone. LEDs or antennas could also be connected, and with minor modifications similar technology could allow clothing to monitor other vital signs such as breathing.
The nanotubes had to be modified slightly – originally the filaments, at just 22 microns wide, were too thin for a sewing machine. A thread was created from three bundles of seven filaments each, woven into a size equivalent to thread. “We worked with somebody who sells little machines designed to make ropes for model ships,” said Taylor, who at first tried to weave the thread by hand, with limited success. “He was able to make us a medium-scale device that does the same.” The fibres were sewn into the shirt in a zigzag pattern that can be adjusted to allow for stretching.
Nanotube fibres were first introduced by Pasquali’s lab in 2013, and have been studied for use in repairing damaged hearts, for brain-machine interfaces, and as flexible antennae. “We see that, after two decades of development in labs worldwide, this material works in more and more applications,” Pasquali said. “Because of the combination of conductivity, good contact with the skin, biocompatibility and softness, carbon nanotube threads are a natural component for wearables.”
Future uses could include control interfaces for cars, soft robotics, or ballistic protection in military uniforms. “We demonstrated with a collaborator a few years ago that carbon nanotube fibres are better at dissipating energy on a per-weight basis than Kevlar, and that was without some of the gains that we’ve had since in tensile strength,” Taylor said.
“We’re in the same situation as solar cells were a few decades ago,” Pasquali said. “We need application leaders that can provide a pull for scaling up production and increasing efficiency.”
Want the best engineering stories delivered straight to your inbox? The Professional Engineering newsletter gives you vital updates on the most cutting-edge engineering and exciting new job opportunities. To sign up, click here.
Content published by Professional Engineering does not necessarily represent the views of the Institution of Mechanical Engineers.