Tech Briefs Magazine - November 2021 - 57

combination of p-types and n-types to function. At the
moment, there is no n-type equivalent to PEDOT:PSS.
Researchers have now developed a conductive n-type polymer
ink that is stable in air and at high temperatures. The new polymer
formulation is known as BBL:PEI. The combination of
PEDOT: PSS and BBL:PEI opens new possibilities for the development
of stable and efficient electronic circuits.
The new n-type material comes in the form of ink with
ethanol as the solvent. The ink can be deposited by simply
spraying the solution onto a surface, making organic electronic
devices easier and cheaper to manufacture. In addition,
the ink is more eco-friendly than many other n-type
organic conductors currently under development that contain
harmful solvents.
Large-scale production is feasible; however, work remains to
be done to adapt the ink to various technologies.
For more information, contact Simone Fabiano at simone.fabiano@
liu.se; +46 11 36 36 33.
" Smart " Shirt Monitors the Heart
Flexible carbon nanotube fibers woven into clothing gather accurate EKG and heart rate.
Rice University, Houston, Texas
S
mart clothing has been developed that employs conductive
nanotube thread to weave functionality into regular apparel.
The fibers were sewn 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.
The shirt was better at gathering data than a standard cheststrap
monitor taking live measurements during experiments.
When matched with commercial medical electrode monitors,
the carbon nanotube shirt gave slightly better EKGs. The shirt
must be snug against the chest; future studies will investigate
denser patches of carbon nanotube threads so there is more
surface area to contact the skin.
The 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. The original nanotube filaments, at about 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.
The zigzag pattern can be adjusted to account for how much a
shirt or other fabric is likely to stretch. Fibers woven into fabric can
also be used to embed antennas or LEDs. Minor modifications to
the fibers' geometry and associated electronics could eventually
allow clothing to monitor vital signs, force exertion, or respiratory
rate. Other potential uses could include human-machine interfaces
for automobiles or soft robotics or as antennas, health monitors,
and ballistic protection in military uniforms.
For more information, contact Mike Williams at mikewilliams@
rice.edu; 713-348-6728.
ISOTROPIC
Silver Conductive
Silicone Adhesive
MasterSil 973S-LO
Features excellent
electrical conductivity
* Meets NASA low
outgassing requirements
* Highly flexible system
* Resists high temperatures
* Cures well in deep
and wide sections
A shirt with carbon nanotube thread provides constant monitoring of the
wearer's heart. (Photo by Jeff Fitlow)
Tech Briefs, November 2021
Cov
ToC
Hackensack, NJ 07601 USA * +1.201.343.8983 * main@masterbond.com
www.masterbond.com
Free Info at http://info.hotims.com/79419-750
57
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Tech Briefs Magazine - November 2021

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