Medical Design Briefs - October 2021 - 24

Sticking Sensors to Skin
Without Adhesives
A recent study explores how
human skin can control the way
cracks form. Researchers develProf.
Guy German developed a
method to bond human skin to
rubber-like polymeric materials
without an adhesive. (Credit:
Bing hamton University)
oped a method to bond human
skin to rubber-like polymeric materials
without an adhesive. They
bonded skin samples to a piece of
polydimethylsiloxane (PDMS), a
rubber-like material commonly
used in bioengineering and biomedical devices. The samples
were then stretched. A modified traction force microscopy technique
was then used to quantify changes in the mechanical loads
imparted by the skin on the adherent substrate.
As the skin expanded, a little crack would grow, and they could
measure how much energy it required to grow it by a certain
length. The cracks propagate along the topographical microchannels.
This elongates the overall path of the crack, increasing the
energy it costs to break the tissue. The discovery can be extrapolated
to explain the behaviors of other human tissues.
Because of the heterogeneous structure of skin, it also means
that the crack path becomes a lot more random, causing variability
in macroscale tensometer measurements. Even though you
get the skin from the same source at the same age, the sampleto-
sample variability is so high because the crack paths deviate.
For more information, visit www.medicaldesignbriefs.com/
roundup/1021/skin.
Dissolvable Microneedle Patch
Treats Baldness
Researchers have designed a minimally
invasive way to deliver cerium-containing
nanoparticles near hair roots deep
under
the skin to promote hair
A new dissolvable microneedle
patch could treat
baldness and help hair
regrow quickly. (Credit:
docent/Shutterstock.com)
re -
growth. As a first step, they coated cerium
nanoparticles with a biodegradable
polyethylene glycol-lipid compound.
Then they made the dissolvable micro -
needle patch by pouring a mixture of
hyaluronic acid - a substance that is naturally abundant in human
skin - and cerium-containing nanoparticles into a mold.
The team tested control patches and the cerium-containing
ones on male mice with bald spots formed by a hair removal cream.
Both applications stimulated the formation of new blood vessels
around the mice's hair follicles. However, those treated with the
nanoparticle patch showed faster signs of hair undergoing a transition
in the root, such as earlier skin pigmentation and higher levels
of a compound found only at the onset of new hair development.
These mice also had fewer oxidative stress compounds in
their skin. Finally, the researchers found that the cerium-containing
microneedle patches resulted in faster mouse hair
regrowth with similar coverage, density, and diameter compared
with a leading topical treatment and could be applied
less frequently. Micro needle patches that introduce cerium
nanoparticles into the skin are a promising strategy to reverse
balding for androgenetic alopecia patients, the researchers say.
For more information, visit www.medicaldesignbriefs.com/
roundup/1021/patch.
24
Intro
Cov
When placed over a fracture,
the device generates electricity
from movement, accelerating
bone healing. (Credit:
Jason Daley)
The proposed system will help
prevent the onset of diabetes.
(Credit: Tokyo University of
Science)
Self-Powered Diaper Sensors
Monitor Urine Sugar Levels
To measure urine sugar levels in
elderly or long-term care patients,
sensors can be embedded directly
into their diapers. By wirelessly
transmitting the acquired data, diaper
sensors can greatly simplify caretaking
and health monitoring tasks.
The scientists developed a
paper-based biofuel cell that, through a pair of reduction-oxidation
reactions, outputs electrical power proportional to the
amount of glucose in the urine. Important considerations in
the design of such biofuel cells are the amount of urine needed
to generate enough power and the overall stability and
durability of the device.
The scientists developed a special anode, the negative terminal
of an electrochemical cell, using a process known as graft polymerization
that allowed them to firmly anchor glucose- reactive
enzymes and mediator molecules to a porous carbon layer, which
served as the base conductive material. They tested their self-powered
biosensor in diapers using artificial urine at various glucose
concentrations. They used the generated energy to power up a
Bluetooth low energy transmitter and remotely monitored the
measured concentration using a smartphone. They found that
the biofuel cell could detect urine sugar within 1 second.
For more information, visit www.medicaldesignbriefs.com/
roundup/1021/sugar.
Self-Powered Implantable
Stimulates Fast Bone Healing
Researchers have developed a
thin, flexible self-powered device that
is implantable and bioresorbable, so
once the bone is knitted back together,
the device's components dissolve
within the body.
To create the new fracture electro -
stimulation device, or FED, they started
with a triboelectric nanogenerator,
and coupled it with a pair of electrodes to distribute the electric
field to the bone. They built these ultrathin, biodegradable, and
bioresorbable components on a substrate of poly(lactic-co-glycolic
acid), a commonly used FDA-approved biocompatible polymer.
Initial tests confirmed that small movements of the device
created an electrical stimulation of about 4 V, which it could
sustain for over six weeks. Animals implanted with the device
completely recovered from a tibia fracture in about six weeks,
much more quickly than animals in a control group. The mineral
density and flexural strength of the healed bones also
reached the same level as healthy bones in the animals that
received the electrostimulation. After the treatment, the
devices degraded and absorbed into the rats' bodies with no
complications and no need for surgical removal.
It's possible to fine-tune how long the stimulator will last
within the body - from weeks to months - by tweaking the
properties of the bioresorbable material coating the device.
For more information, visit www.medicaldesignbriefs.com/
roundup/1021/bone.
www.medicaldesignbriefs.com
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http://www.medicaldesignbriefs.com/roundup/1021/skin http://www.medicaldesignbriefs.com/roundup/1021/sugar http://www.medicaldesignbriefs.com/roundup/1021/bone http://www.medicaldesignbriefs.com/roundup/1021/patch http://www.medicaldesignbriefs.com http://info.hotims.com/79418-966
Medical Design Briefs - October 2021

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