Researchers have developed ‘smart clothing’ which is able to monitor heartrate and take a continual electrocardiogram (EKG) of the wearer.
A team of engineers from the Brown School of Engineering at Rice University, Texas, USA, used nanotube fibres sewn into sportswear to continually track heartrate and electrical activity of the heart. Researchers found that a shirt enhanced with these fibres was more effective at gathering data than a standard chest-strap monitor taking live measurements during experiments.
The research findings have been reported in the journal Nano Letters.
The researchers say that the fibres are just as conductive as metal wires, but have the added benefit of being washable, comfortable, and far less likely to break when a body is in motion.
The researchers said that the nanotube fibres are soft and flexible, and clothing that incorporates them is machine washable. The fibres can be sewn into fabric by a machine in the same way as standard thread. The zigzag stitching pattern allows the fabric to stretch without breaking them. The fibres provided not only steady electrical contact with the wearer’s skin but also serve as electrodes to connect electronics like Bluetooth transmitters to relay data to a smartphone.
Rice graduate student Lauren Taylor, lead author of the study, said: “The shirt has to be snug against the chest.
“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 laboratory of chemical and biomolecular engineer Matteo Pasquali, at the Brown School of Engineering, first introduced carbon nanotube fibre in 2013. Since then, the fibres, each containing tens of billions of nanotubes, have been studied for use as bridges to repair damaged hearts, as electrical interfaces with the brain, for use in cochlear implants, as flexible antennas, and for automotive and aerospace applications. Their development is also part of the Rice-based Carbon Hub, a multi-university research initiative led by Rice and launched in 2019.
The original nanotube filaments, that were around 22 microns wide, were too thin for a sewing machine to handle. A rope-maker was used to create a sewable thread, essentially three bundles of seven filaments each, woven into a size roughly equivalent to regular thread.
Taylor explained: “We worked with somebody who sells little machines designed to make ropes for model ships.
“He was able to make us a medium-scale device that does the same.”
Taylor said that the zigzag pattern can be adjusted to account for how much a shirt or other fabric is likely to stretch. She went on to explain that the team is working with Dr Mehdi Razavi and his colleagues at the Texas Heart Institute to develop a way in which to maximise contact with the skin.
The researchers added that fibres woven into fabric can also be used to embed antennas or LEDs. It is hoped that, with minor modifications to the fibres’ geometry and associated electronics, clothing could eventually be used to monitor vital signs, force exertion, or respiratory rate.