Medical Design Briefs - May 2021 - 32

and to compare them with other
measurements from the patient. At
best, the system would produce automatic alarms to sound warnings about
changes in the patient's condition,
such as cardiac events or blood poisoning. With the help of the right
kinds of analysis, a smart patch could
also help people monitor their own

fitness and health in the way that
smartwatches and smart rings do -
only more accurately.
VTT expects the first smart patches
to reach the market within two or
three years. The research projects
have already taken a step toward solutions at the next level, epidermal electronics that would be even less notice-

able for the user than a smart patch.
Some of the research also targets
patches that combine electronic measurement of vital functions with biochemical analysis - for measuring
sweat, for example.
For more information, visit www.vtt.fi.
Contact Teemu Alajoki at teemu.alajoki@
vtt.fi.

Study Proposes Low-Cost, High-Efficiency Mask Design
Modifications to existing
N95 masks improve their
reusability.

(a)

(b)
Pressure

Oxford University Press
Oxford, UK
Low-cost modifications to existing N95
masks can prolong their effectiveness
and improve their reusability post disinfectants. A paper in Oxford Open Materials
Science, published by Oxford University
Press, details the new design.
The COVID-19 crisis has increased
demand for respiratory masks, with various models of DIY masks becoming popular alongside the commercially available N95. The utility of such masks is primarily based on the size of aerosols that
they are capable of filtering out and how
long they can do so effectively.
Conventional masks like the N95 use a
layered system and have an efficiency
rate of 95 percent. Yet, this rate begins to
drop after someone wears them for
more than eight hours. This is due to
the fact that N95 masks were designed
for single use. The high demand caused
by COVID-19 has led people to disinfect
them for reuse. As such, a team of scientists have put together various techniques for decontamination and reuse
of respiratory masks based on experimental data and guidelines issued by
Center for Disease Control.
Researchers have proposed a low cost
($1), tri-layer mask design containing
nylon, modified polypropylene, and nonwoven cotton fabrics. While the polypropylene layer is available in N95 masks,
this design includes a graphene oxide
and polyvinylidene fluoride mixture that
acts as an active filtration layer.
Recent studies show that the graphene
oxide mixture has a high antibacterial
activity, making it ideal for respiratory
masks. This coating has also proven to be
effective even after being disinfected

Material
Electrode

Material
Electrode
Electrode
(c)

Aerosol Generator
By-Pass

Input medium
Input Flow Control

Exit Flow Control
Output Electrical Feed Through

Input Electrical Feed Through
BME280

SPS30
Sample BME280

Schematic of the triboelectric voltage measurement set up. The " material " is the membrane being
tested. Oscilloscope (Model: Tektronix TBS1102B) was used to record the voltage generated via
triboelectricity (a). Schematic representation of the charge measurements using an analog electrometer (Model: Keithley 610C) (b). Schematics of the membrane testing system: (top) crosssectional 3D view and (bottom) block diagram showing the different parts (c). (Credit: Oxford Open
Materials Science)

with H2O2, a popular practice when
reusing masks. The addition of these
membranes results in an efficiency level
of 95 percent, like that of an N95, while
also simplifying the number of layers in
the design for increased comfort.
" The possibility to produce cost effective reusable N95 masks that can help
the public health system and common
citizens motivated the work. We tried to
leverage the connection between elec-

www.medicaldesignbriefs.com

Cov

ToC

trostatic charge and the filtration efficiency of masks for submicron size particles and viruses to come up with a design
to make N95 masks reusable, " says Dr. G.
Rajalakshmi.
These cheap and simple modifications can provide people in all socioeconomic classes with a long-lasting,
high-filtration respiratory mask.
For more information, visit https://global.
oup.com.
Medical Design Briefs, May 2021

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Medical Design Briefs - May 2021

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