Medical Design Briefs - November 2021 - 8

HONORABLE MENTIONS
'Smart' Wearable Sensor for Continuous Monitoring of Wound Healing
Keith J. Stevenson, Professor and Provost, Skolkovo Institute of Science and Technology
Olja Simoska, ACS Irving S. Sigal Postdoctoral Fellow, University of Utah
C
hronic wounds that fail to heal
quickly, such as diabetic foot
ulcers or pressure ulcers, can be
very tricky to manage for healthcare
professionals and affect the life quality
of patients. The treatment strategies
are not only a healthcare burden but
also present a challenge because early
symptoms of developing wounds are
difficult to ascertain. To monitor healing
processes and assess the need for
treatment, doctors and nurses normally
need to remove the bandages from a
wound, which harms the recovering tissue,
often hurting the patient and
requiring frequent hospital visits to
avoid further developing infections.
Furthermore, if wound inspection re -
quires more than just visual examination,
using other methods including tissue
biopsies, surface swabs, or testing
for pathogenic bacteria. These approaches
are invasive and costly procedures
that can take days and yet fail to
produce useful treatment protocols.
However, the development of smart
bandages, which are essentially wearable
sensors that can monitor certain
biomarkers during the wound-healing
process, have captured the attention of
medical professionals.
Electroanalytical methods are particularly
promising for clinical applications
due to their relative simplicity, sensitivity,
durability, and other attractive characterAntimicrobial
Silver (Ag+
)
1.2
0.9
0.6
0.3
0.0
Carbon Ultramicroelectrode Arrays
on a Flexible Substrate
Cellular Culture in
Wound Fluid Simulant
Redox Bacterial Toxins
Fast Detection
(Few Seconds)
8
Cov
www.medicaldesignbriefs.com
ToC
-0.8
-0.6
-0.4
-0.2
Potential (V vs. SCE)
istics. The team created
a prototype of a
wearable electroanalytical
sensor, based
on carbon ultramicroelectrode
arrays
(CUAs) on flexible
substrates, to monitor
chronic wound
activity. These lowcost
devices (~$12
per sensor) can
quantitatively measure
the state of
wound healing, in
real time, and provide
a smart dressing
to deliver wound
Signal
Electrode Sensor
Carbon Ultramicroelectrode
Arrays Sensor
p. aeruginosa
Bacterial Toxins
Bacteria Detected
a
b
25
20
15
10
5
400 nm
0 5 10 15 20 25
d=1.54 ± 0.056 μm
a=0.097 ± 0.009 μm
Distance (µm)
Carbon utramicroelectrode array
sensor on a flexible substrate
Top-view of carbon ultramicroelectrode
array sensor with numerous individual
electrodes in the array
treatment. The sensors are designed via a
unique combination of carbon and
metal oxide materials, resulting in
nanometer sizes and array-based geometry
that provide enhanced sensitivity for
sensing in complex biological samples.
Additionally, CUAs provide rapid detection
(~seconds) and continual monitoring
of wound-healing state and infection
by chemically tracking critical signaling
molecules in chronic wounds.
A simulated wound environment was
used to test the sensitivity of CUAs to
three critical chronic wound biomarkers:
(1) pyocyanin, a toxin molecule produced
by Pseudomonas aeruginosa, a highly
infectious bacterium typically colonizNanoscale
image of an individual carbon
electrode in the array
c
Decreasing Bacterial
Toxin Production
Background
0 min Ag+
10 min Ag+
30 min Ag+
ing chronic wounds, (2) nitric oxide
secreted in response to bacterial infections
by cells of the immune system, and
(3) uric acid, a metabolite that strongly
correlates with the severity of a wound.
All these compounds are electroactive;
they respond to electrical activity that
can be detected by the electroanalytical
sensor. The characterized CUAs limit of
detection and linear dynamic ranges,
namely the concentration ranges where
a sensor produces meaningful quantitative
results, are within the biologically
relevant concentrations. The sensor was
also tested with cell cultures to successfully
detect pyocyanin from P. aeruginosa
and nitric oxide from macrophages
(immune cells that destroy
bacteria and other invaders).
Finally, the sensor
detects the influence of silver
(Ag+) ions, a well-known
antimicrobial agent, that
suppresses pyocyanin production
by the bacteria.
Unlike other smart bandage
devices, the platform
demonstrates sensitivity and
selective detection of various
analytes in complex
wound fluid stimulants,
closely mimicking real biological
environments. Thus,
these engineered sensors
have the potential to be a
simple and effective solution
in the treatment, monitoring,
and healing of
chronic wounds in clinical
settings.
-0.0
Medical Design Briefs, November 2021
Current (µA)
Distance (µm)
http://www.medicaldesignbriefs.com
Medical Design Briefs - November 2021

Table of Contents for the Digital Edition of Medical Design Briefs - November 2021
