Medical Design Briefs - January 2023 - 26

n Novel Device Measures
Nerve Activity
Researchers have developed a device to
noninvasively measure cervical nerve activity
in humans. The new tool could potentially
inform and improve treatments
for patients with sepsis, a life-threatening
response to infection, and mental health
conditions, such as post-traumatic stress
disorder (PTSD).
The new device features a flexible array
of electrodes that stretch from the lower
The electrode array is
small, noninvasive and
can be worn for up to
a day. (Credit: UCSD)
front to the upper back of the neck, allowing
researchers to capture electrical
activity across different nerves. An integrated
user interface enables real-time
visualization of data, and a custom algorithm groups persons
according to their nervous systems' response to stress.
The researchers ran a series of tests that asked study participants
to place and hold their hand in ice water, followed by a
timed breathing exercise. The array recorded cervical nerve
signaling or cervical electroneurography, including heart rate
in subjects before and after both the ice water challenge and
during the breathing exercise. The electrode array could not
identify the precise nerves firing in response to the stress and
pain of the cold-water challenge.
For more information, visit www.medicaldesignbriefs.com/
roundup/0123/nerve.
n Printable, Transparent
Plastic Is Highly
Conductive
Researchers have deThe
transparent polymer conducts
electricity
effectively
and
is
initially
a
bluish tint when it's cast as a film.
Further processing results in a flexible,
highly conductive, transparent
plastic. (Credit: James Ponder)
signed a transparent polymer
film that conducts electricity
as effectively as other
commonly used materials,
while also being flexible and
easy to use at an industrial
scale. The resulting process
could yield new kinds of flexible,
transparent electronic devices such as wearable biosensors.
To make a plastic film that can carry an electric charge, chemists
start with a known polymer backbone - in this case, a popular
polymer called PEDOT that is used in industry in certain
formulations. It's great for conducting electricity, but difficult to
use in its bare form because it's insoluble. However, when side
chains are added to the PEDOT, it can be dissolved and used
like a printable ink or a spray paint. That makes it easy to use
and apply. Unfortunately, those side chains are essentially waxy
material, and wax isn't so great at electrical conductivity.
The team creates the polymer with side chains, prints or
sprays it to apply, chemically cleaves the side chains, and washes
them away with common industrial solvents. After a final conversion
step, the result is a flexible, highly conductive film that
is stable and impervious to water or other solvents.
The material, which they call PEDOT(OH), can be easily
processed to thick films that maintain their conductivity.
For more information, visit www.medicaldesignbriefs.com/
roundup/0123/conductive.
26
n Printing Flexible
Circuits on Curved
Surfaces
Researchers have demonstrated
a new technique for
directly
printing
A new technique directly prints electronic
circuits onto curved and corrugated
surfaces. (Credit: Yuxuan Liu)
electronic
circuits onto curved and corrugated
surfaces. The work
paves the way for a variety of
new soft electronic technologies,
and researchers have
used the technique to create prototype smart contact lenses,
pressure-sensitive latex gloves, and transparent electrodes.
The first step in the new technique is to create a template for
the relevant application that incorporates a specific pattern of
microscale grooves. The template is then used to replicate that
pattern in a thin elastic polymer film. Researchers then attach
the thin polymer film to the relevant substrate, which can be flat
or curved. The tiny grooves in the polymer are filled with a liquid
solution containing silver nanowires. The solution is allowed
to dry at room temperature, leaving behind silver nanowires in
a soft material with the desired shape and circuit pattern.
To demonstrate the technique, the researchers created three
proof-of-concept prototypes. One was a smart contact lens with
built-in circuits, which could be used to measure the fluid pressure
of the eye. Another was a flexible, transparent electrode
with circuits printed in a grid pattern. The third was a latex glove
that has circuits printed on it that serve as pressure sensors.
For more information, visit www.medicaldesignbriefs.com/
roundup/0123/printing.
n Magnetic Sensors Track
Muscle Length
A
small,
bead-like magnet used
in a new approach to measuring
muscle position. (Credit: MIT)
Using a simple set of magnets,
researchers have devised a
sophisticated way to monitor
muscle movements, which they
hope will make it easier for people
with amputations to control
their prosthetic limbs. The researchers
have demonstrated
the accuracy and safety of their magnet-based system, which
can track the length of muscles during movement. The studies,
performed in animals, offer hope that this strategy could be
used to help people with prosthetic devices control them in a
way that more closely mimics natural limb movement.
Their strategy takes advantage of the permanent magnetic
fields surrounding small beads implanted in a muscle. Using a
credit-card-sized, compass-like sensor attached to the outside of
the body, their system can track the distances between the two
magnets. When a muscle contracts, the magnets move closer
together, and when it flexes, they move further apart.
In one study, the researchers showed that this system could
be used to accurately measure small ankle movements when
the beads were implanted in the calf muscles of turkeys. In one
of the new studies, the researchers set out to see whether the
system could make accurate measurements during more natural
movements in a non-laboratory setting.
For more information, visit www.medicaldesignbriefs.com/
roundup/0123/magnetic.
www.medicaldesignbriefs.com
Medical Design Briefs, January 2023
http://www.medicaldesignbriefs.com/roundup/0123/nerve http://www.medicaldesignbriefs.com/roundup/0123/printing http://www.medicaldesignbriefs.com/roundup/0123/magnetic http://www.medicaldesignbriefs.com/roundup/0123/conductive http://www.medicaldesignbriefs.com
Medical Design Briefs - January 2023

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