`Smart' shirt keeps tabs on the heart
Flexible carbon nanotube fibers woven into clothing gather accurate EKG,
heart rate

Date:
August 30, 2021
Source:
Rice University
Summary:
Carbon nanotube thread woven into athletic shirts gathered
electrocardiogram and heart rate data that matched standard
monitors and beat chest-strap monitors. The fibers are flexible
and the shirts are machine washable.



FULL STORY ========================================================================== There's no need to don uncomfortable smartwatches or chest straps to
monitor your heart if your comfy shirt can do a better job.


========================================================================== That's the idea behind "smart clothing" developed by a Rice University
lab, which employed its conductive nanotube thread to weave functionality
into regular apparel.

The Brown School of Engineering lab of chemical and biomolecular engineer Matteo Pasquali reported in the American Chemical Society journal Nano
Letters that it sewed nanotube fibers into athletic wear to monitor the
heart rate and take a continual electrocardiogram (EKG) of the wearer.

The fibers are just as conductive as metal wires, but washable,
comfortable and far less likely to break when a body is in motion,
according to the researchers.

On the whole, the shirt they enhanced was better at gathering data
than a standard chest-strap monitor taking live measurements during experiments. When matched with commercial medical electrode monitors,
the carbon nanotube shirt gave slightly better EKGs.

"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 researchers noted nanotube fibers
are soft and flexible, and clothing that incorporates them is machine
washable. The fibers can be machine-sewn into fabric just like standard
thread. The zigzag stitching pattern allows the fabric to stretch without breaking them.



==========================================================================
The fibers provided not only steady electrical contact with the wearer's
skin but also served as electrodes to connect electronics like Bluetooth transmitters to relay data to a smartphone or connect to a Holter monitor
that can be stowed in a user's pocket, Taylor said.

Pasquali's lab introduced carbon nanotube fiber in 2013. Since then the
fibers, 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 multiuniversity research initiative led
by Rice and launched in 2019.

The original nanotube filaments, at about 22 microns wide, were too thin
for a sewing machine to handle. Taylor said 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.

"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." She said the zigzag pattern can be adjusted to
account for how much a shirt or other fabric is likely to stretch. Taylor
said the team is working with Dr.

Mehdi Razavi and his colleagues at the Texas Heart Institute to figure
out how to maximize contact with the skin.



========================================================================== Fibers woven into fabric can also be used to embed antennas or LEDs,
according to the researchers. Minor modifications to the fibers' geometry
and associated electronics could eventually allow clothing to monitor
vital signs, force exertion or respiratory rate.

Taylor noted other potential uses could include human-machine interfaces
for automobiles or soft robotics, or as antennas, health monitors and
ballistic protection in military uniforms. "We demonstrated with a
collaborator a few years ago that carbon nanotube fibers 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," she said.

"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." He said the wearable market, although
relatively small, could be an entry point for a new generation of
sustainable materials that can be derived from hydrocarbons via direct splitting, a process that also produces clean hydrogen.

Development of such materials is a focus of the Carbon Hub.

"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." Co-authors of the
paper are Rice graduate students Steven Williams and Oliver Dewey, and
alumni J. Stephen Yan, now at Boston Consulting Group, and Flavia Vitale,
an assistant professor of neurology at the University of Pennsylvania.

Pasquali is director of the Carbon Hub and the A.J. Hartsook Professor
of Chemical and Biomolecular Engineering and a professor of chemistry
and of materials science and nanoengineering.

The research was supported by the U.S. Air Force (FA9550-15-1-0370), the American Heart Association (15CSA24460004), the Robert A. Welch Foundation
(C- 1668), the Department of Energy (DE-EE0007865, DE-AR0001015), the Department of Defense (32 CFR 168a) and a Riki Kobayashi Fellowship from
the Rice Department of Chemical and Biomolecular Engineering.

Video of flexible carbon nanotube fibers woven into clothing gather
accurate EKG, heart rate: https://www.youtube.com/watch?v=YZbcSGvwu4Y ========================================================================== Story Source: Materials provided by Rice_University. Original written
by Mike Williams. Note: Content may be edited for style and length.


========================================================================== Journal Reference:
1. Lauren W. Taylor, Steven M. Williams, J. Stephen Yan, Oliver
S. Dewey,
Flavia Vitale, Matteo Pasquali. Washable, Sewable, All-Carbon
Electrodes and Signal Wires for Electronic Clothing. Nano Letters,
2021; DOI: 10.1021/acs.nanolett.1c01039 ==========================================================================

Link to news story: https://www.sciencedaily.com/releases/2021/08/210830123233.htm

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