Tech Briefs Magazine - August 2021 - 47

In tests, subjects wore the patch on
the neck while performing various combinations
of the following tasks: exercising
on a stationary bicycle, eating a highsugar
meal, drinking an alcoholic beverage,
and drinking a caffeinated beverage.
Measurements from the patch
closely matched those collected by commercial
monitoring devices such as a
blood pressure cuff, blood lactate meter,
glucometer, and breathalyzer.
One of the biggest challenges in making
the patch was eliminating interference
between the sensors' signals. To do
this, the researchers had to figure out
the optimal spacing between the blood
pressure sensor and the chemical sensors.
They found that one centimeter of
spacing did the trick while keeping the
device as small as possible.
Wearing the patch on the neck provides optimal readout.
sensor provides a separate picture of a
physical or chemical change. Integrating
them all in one wearable patch allows
those different pictures to be used to -
gether to get a more comprehensive
overview of what's going on in the body.
The patch is a thin sheet of stretchy
polymers that can conform to the skin. It
is equipped with a blood pressure sensor
and two chemical sensors - one that
measures levels of lactate (a biomarker
of physical exertion), caffeine, and alcohol
in sweat and another that measures
glucose levels in interstitial fluid. The
patch is capable of measuring three
parameters at once, one from each sensor:
blood pressure, glucose, and either
lactate, alcohol, or caffeine.
The blood pressure sensor sits near
the center of the patch. It consists of a
set of small ultrasound transducers that
are welded to the patch by a conductive
ink. A voltage applied to the transducers
causes them to send ultrasound waves
into the body. When the ultrasound
waves bounce off an artery, the sensor
detects the echoes and translates the signals
into a blood pressure reading.
The chemical sensors are two electrodes
that are screen-printed on the
patch from conductive ink. The electrode
that senses lactate, caffeine, and
alcohol is printed on the right side of
the patch; it works by releasing a drug
called pilocarpine into the skin to
induce sweat and detecting the chemical
substances in the sweat. The other electrode,
which senses glucose, is printed
on the left side; it works by passing a
mild electrical current through the skin
to release interstitial fluid and measuring
the glucose in that fluid.
Nearly Pain-Free Microneedle Patch
The patch can replace blood draws to test for antibodies that signal a viral or bacterial
infection such as SARS-CoV-2.
Washington University in St. Louis, Missouri
D
octors often use blood samples to
check for biomarkers of disease
such as antibodies or cytokines indicative
of inflammation seen in conditions
such as rheumatoid arthritis and sepsis.
These biomarkers are not just in
blood - they can also be found in the
dense liquid medium that surrounds
cells but in a low abundance that makes
it difficult to be detected.
Tech Briefs, August 2021
Cov
Engineers have developed a micro -
needle patch that can be applied to the
skin, capture a biomarker of interest,
and thanks to its unprecedented sensitivity,
allow clinicians to detect its presence.
The technology is low-cost, easy for clinicians
or patients themselves to use, and
could eliminate the need for a trip to the
hospital just for a blood draw. In addition,
the microneedle patches have
www.techbriefs.com
ToC
another advantage over blood draws:
they are nearly pain-free.
Finding a biomarker using the
micro needle patches is similar to
blood testing but instead of using a
solution to find and quantify the biomarker
in blood, the microneedles
directly capture it from the liquid that
surrounds cells in the skin, which is
called dermal interstitial fluid (ISF).
47
They also had to figure out how to
physically shield the chemical sensors
from the blood pressure sensor. The latter
normally comes equipped with a liquid
ultrasound gel in order to produce
clear readings. But the chemical sensors
are also equipped with their own hydrogels
and if any liquid gel from the blood
pressure sensor flows out and makes
contact with the other gels, it will cause
interference between the sensors. In -
stead, the researchers used a solid ultrasound
gel that works as well as the liquid
version but without the leakage.
Ongoing work includes shrinking the
electronics for the blood pressure sensor.
Right now, the sensor needs to be connected
to a power source and a benchtop
machine to display its readings. The ultimate
goal is to put these all on the patch
and make everything wireless.
For more information, contact Liezel
Labios at llabios@ucsd.edu; 858-246-1124.
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Tech Briefs Magazine - August 2021

Table of Contents for the Digital Edition of Tech Briefs Magazine - August 2021

Tech Briefs Magazine - August 2021 - Intro
Tech Briefs Magazine - August 2021 - Sponsor
Tech Briefs Magazine - August 2021 - Cov1
Tech Briefs Magazine - August 2021 - Cov2
Tech Briefs Magazine - August 2021 - 1
Tech Briefs Magazine - August 2021 - 2
Tech Briefs Magazine - August 2021 - 3
Tech Briefs Magazine - August 2021 - 4
Tech Briefs Magazine - August 2021 - 5
Tech Briefs Magazine - August 2021 - 6
Tech Briefs Magazine - August 2021 - 7
Tech Briefs Magazine - August 2021 - 8
Tech Briefs Magazine - August 2021 - 9
Tech Briefs Magazine - August 2021 - 10
Tech Briefs Magazine - August 2021 - 11
Tech Briefs Magazine - August 2021 - 12
Tech Briefs Magazine - August 2021 - 13
Tech Briefs Magazine - August 2021 - 14
Tech Briefs Magazine - August 2021 - 15
Tech Briefs Magazine - August 2021 - 16
Tech Briefs Magazine - August 2021 - 17
Tech Briefs Magazine - August 2021 - 18
Tech Briefs Magazine - August 2021 - 19
Tech Briefs Magazine - August 2021 - 20
Tech Briefs Magazine - August 2021 - 21
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Tech Briefs Magazine - August 2021 - 47
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Tech Briefs Magazine - August 2021 - Cov3
Tech Briefs Magazine - August 2021 - Cov4
Tech Briefs Magazine - August 2021 - MD-Cov1
Tech Briefs Magazine - August 2021 - MD-Cov2
Tech Briefs Magazine - August 2021 - MD-1
Tech Briefs Magazine - August 2021 - MD-2
Tech Briefs Magazine - August 2021 - MD-3
Tech Briefs Magazine - August 2021 - MD-4
Tech Briefs Magazine - August 2021 - MD-5
Tech Briefs Magazine - August 2021 - MD-6
Tech Briefs Magazine - August 2021 - MD-7
Tech Briefs Magazine - August 2021 - MD-8
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Tech Briefs Magazine - August 2021 - MD-10
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Tech Briefs Magazine - August 2021 - MD-13
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Tech Briefs Magazine - August 2021 - MD-29
Tech Briefs Magazine - August 2021 - MD-30
Tech Briefs Magazine - August 2021 - MD-31
Tech Briefs Magazine - August 2021 - MD-32
Tech Briefs Magazine - August 2021 - MD-33
Tech Briefs Magazine - August 2021 - MD-34
Tech Briefs Magazine - August 2021 - MD-35
Tech Briefs Magazine - August 2021 - MD-36
Tech Briefs Magazine - August 2021 - MD-37
Tech Briefs Magazine - August 2021 - MD-38
Tech Briefs Magazine - August 2021 - MD-39
Tech Briefs Magazine - August 2021 - MD-40
Tech Briefs Magazine - August 2021 - MD-Cov3
Tech Briefs Magazine - August 2021 - MD-Cov4
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