Tech Briefs Magazine - July 2022 - 8

Keeping the Bugs at Bay
A nature-inspired surface technology for repelling contamination.
I
f you can scare off water, you can
scare off pathogens. That's the logic
behind the bacteria- and virus-shedding
plastic wrap created by
Leyla Soleymani, a professor of engineering
physics and biomedical engineering
at McMaster University, and
Tohid Didar, a mechanical and biomedical
engineer there.
The inspiration for a bug-sloughing
plastic comes from a bit of superhydrophobic
foliage produced by
nature: the lotus leaf. It sits on water
but stays dry; when water comes in
contact with its surface, it beads up
and rolls off at the earliest opportunity.
" It looks smooth, but is rough at
the small scale, " said Soleymani. The
plant owes its magic to nanoscopic structures that trap air bubbles
- and it's the bubbles that are ultimately responsible for
the repellent nature of the leaf.
Soleymani and Didar's film has a similar structure, with nanoscale
towers to trap the air bubbles. It repels water, blood,
mucus, and all the bacteria and viruses that might be contained
therein. And, for extra repellency, she and her colleagues modified
the film with a fluorosilane coating - a variant of the
chemical used to make Teflon nonstick. The combination gave
rise to a plastic film that could be applied to anything anywhere
to keep it bacteria free. It also won Soleymani, Didar, and their
team SAE's Create the Future Design Contest award in 2020.
2020 GRAND PRIZE WINNER
INNOVATORS: Leyla Soleymani
(left) and Tohid Didar.
INNOVATION: A flexible plastic
wrap that works instantly to repel a
wide range of contaminants.
bacterial and viral pathogens, including the coronavirus.
Learn more about the 20th
www.createthefuturecontest.com
8
IMPACT: With its instant repellency
and antimicrobial nanoparticles,
RepelWrap can shed many types of
Anniversary Contest at
The Covid-19 pandemic was in
its early bloom that year and the
world was craving anything that
might keep the virus at bay. " We
did get some interesting funding
that I think would have been difficult
to get otherwise, " said Soleymani.
With it she started a company
with the aim of creating a
commercial product, which they
are calling RepelWrap.
Though the germ repellent
film is not yet on the shelves, Soleymani
and her team have made
some major advancements. Back
in 2020, they had only proved
that the film repelled bacteria.
Now they've shown that it also
sheds 99.99 percent of any viral load that comes its way. And
one of the viruses they tested it with was a coronavirus variant
that causes a common cold. It stood no chance against
the film.
They've also put the RepelWrap through its paces, proving,
with repeated touches from human hands as well as
stamps from a robot that the film is durable and maintains
its essential qualities after months. Though the extended
use does result in a " slight deformation of the structural hierarchy, "
as Soleymani puts it, it has little impact on the antimicrobial
aspects of the material.
What's more, the film's antimicrobial properties are no
longer limited to what might be called passive superhydrophobicity.
By including antimicrobial nanoparticles like titanium
dioxide, the researchers have made their film deadly
to the microscopic villains. Now the tiny percentage of bacteria
and viruses that manage to linger on a RepelWrap coated
object are quickly dispatched. " If few manage to attach to
the surface, they are killed by the antimicrobial effect of
these nanoparticles, " said Didar.
But, aside from a few pens and other knickknacks in the
lab, few things in the wider world have been swaddled in
Soleymani and Didar's film. There's still much to be done.
For one thing, the substrates go through considerable
shrinking during production, which makes roll-to-roll manufacturing
more complicated than it is for other films. And
the material has yet to be tested with fungi. " It's been on our
to-do list for some time, " said Soleymani.
" We're still in the process, " she said. " It turns out that scaling
up, to go to large volume manufacturing - it takes longer
than you think. "
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Tech Briefs, July 2022
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Tech Briefs Magazine - July 2022

Table of Contents for the Digital Edition of Tech Briefs Magazine - July 2022

Tech Briefs Magazine - July 2022 - Intro
Tech Briefs Magazine - July 2022 - Sponsor
Tech Briefs Magazine - July 2022 - Cov1
Tech Briefs Magazine - July 2022 - Cov2
Tech Briefs Magazine - July 2022 - 1
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