Medical Design Briefs - November 2021 - 29

The conductivity of the ink can double as
electrical wiring. (Credit: Michigan Tech)
3D Printable Polymer
Nanocomposite Ink
Researchers have created
a way to make a 3D
printable nanocomposite
polymeric ink that uses
carbon nanotubes (CNTs)
- known for their high
tensile strength and lightness.
This revolutionary ink could replace epoxies - and
understanding why its properties are so fantastic is a first step
toward its mass use.
Adding low-dimensional nanomaterials such as CNTs,
graphene, metal nanoparticles, and quantum dots allows 3D
printed materials to adapt to external stimuli, giving them
features such as electrical and thermal conductance, magnetism,
and electrochemical storage.
The conductivity of nanomaterial ink is an exceptionally
handy trait that gives the printed epoxy the potential to double
as electrical wiring such as those in 3D printed actuators
for guiding catheters in blood vessels. Another useful trait of
the nanocomposite polymer ink is its strength. The nanocomposites
also serve a safety function.
For more information, visit www.medicaldesignbriefs.com/
roundup/1121/ink.
The liquid gallium adhered to the fibers
as the ethanol evaporated. (Credit: Vi
Khanh Truong)
Liquid Metal
Coating Creates
Antimicrobial Fabric
A team of researchers
used liquid gallium to create
an antiviral and antimicrobial
coating and tested
it on a range of fabrics,
including facemasks. The
coating adhered more
strongly to fabric than some conventional metal coatings
and eradicated 99 percent of several common pathogens
within five minutes.
The researchers placed liquid gallium (Ga) into an ethanol
solution and used sound waves - a process known as sonication
- to create Ga nanoparticles. The nanoparticle solution
was then spray coated onto the fabric, and the Ga adhered to
the fibers as the ethanol evaporated.
Then the researchers dipped the Ga-coated fabric into a
copper sulfate solution, creating a spontaneous galvanic
replacement reaction. The reaction deposits copper onto
the fabric, creating a coating of liquid metal copper alloy
nanoparticles.
To test the coated fabric's antimicrobial properties, the team
exposed the fabric to three common microbes: Staphylococcus
aureus, Escherichia coli, and Candida albicans. These microbes
grow aggressively on noncoated fabrics. The copper alloy coated
fabric eradicated over 99 percent of the pathogens within
five minutes, which was significantly more effective than control
samples coated with only copper.
For more information, visit www.medicaldesignbriefs.com/
roundup/1121/antimicrobial.
Medical Design Briefs, November 2021
Cov
Smart Fabric Stiffens
on Demand
The chain mail fabric is flexible
like cloth. (Credit: Nanyang
Technological University)
A new type of chain mail fabric
is flexible like cloth but can stiffen
on demand. The lightweight fabric
is 3D printed from nylon plastic
polymers and comprises hollow
octahedrons (a shape with eight
equal triangular faces) that interlock
with each other.
When encased in a plastic envelope and vacuum-packed, it
becomes 25 times more rigid and can hold up over 50 times its
own weight. The chain mail fabric can also be made from 3D
printed aluminum that can harden to protect a user against a
stronger impact.
This next-generation fabric paves the way for exoskeletons
that can help the elderly to stand, walk, and carry objects.
Moving forward, the team is looking to improve the material
and fabric performance of their chain mail and to explore
more methods of stiffening it, such as through magnetism,
electricity, or temperature.
For more information, visit www.medicaldesignbriefs.com/
roundup/1121/fabric.
Low-Power Electrical
Stimulation Could Aid
Stroke Rehabilitation
A new electrical brain stimulaSynaptic
remapping by electrical
stimulation after stroke.
(Credit: DGIST)
tion technique could improve
the recovery of patients from
strokes. The technique uses less
energy and has fewer side effects
than
existing
methods.
The
researchers developed a method
called subthreshold electrical stimulation,
through which a lowpower
electrical signal can be applied to neurons at a synapse
- a junction between two neurons where electric nerve
impulses are transmitted.
The physical experiment involved the subthreshold electrical
stimulation of post-synaptic neurons in rats' brains. At the
same time, the rats were running on a wheel, which naturally
stimulated the pre-synaptic neurons. This process was performed
twice a day for 16 days. At the end of the treatment,
they monitored the rats' behavior and tested for the presence
of proteins that signify neuronal recovery.
The results showed that neither exercise nor subthreshold
electrical stimulation alone were able to initiate a nerve
impulse at the synapse. However, when they occurred simultaneously,
the neurons reached the threshold required to fire a
signal. The researchers found that the stimulated brain regions
contained higher levels of specific neural proteins, indicating
that neural reconstruction had taken place. The results imply
that subthreshold electrical stimulation, when combined with
motor training early in rehabilitation, may strengthen connections
between brain regions and aid motor recovery.
For more information, visit www.medicaldesignbriefs.com/
roundup/1121/stroke.
www.medicaldesignbriefs.com
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http://www.medicaldesignbriefs.com/roundup/1121/fabric http://www.medicaldesignbriefs.com/roundup/1121/ink http://www.medicaldesignbriefs.com/roundup/1121/stroke http://www.medicaldesignbriefs.com/roundup/1121/antimicrobial http://www.medicaldesignbriefs.com
Medical Design Briefs - November 2021

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