The benefits of wearing face masks to support the spread of COVID-19 are now well understood, but scientists are still looking for better materials to use – and a ‘filter paper’ made of titanium oxide nanowires shows much promise.
The new material is so good at capturing pathogens, and destroying it when ultraviolet light is applied, it could also be used in air conditioning units and ventilation systems, according to the developers.
While the nanowire-based mask looks like it was made from normal filter paper, it adds extra antibacterial and antiviral properties to the material, making it much more effective at eliminating germs – and also making them reusable.
“Since our filter is exceptionally good at absorbing moisture, it can trap droplets carrying viruses and bacteria,” says physicist László Forró, of the Complex Matter Laboratory for Complex Matter at EPFL in Switzerland.
“This provides a favorable environment for the oxidation process, which is triggered by light.”
The photocatalytic properties of titanium dioxide are important – when ultraviolet light hits the mask, the fibers convert moisture held in the nanowires into oxidizing agents (including hydrogen peroxide), which then have the potential to destroy pathogens on contact.
In experiments on the material, the team showed how the filter could be destroyed Escherichia coli bacteria and degrade strands of DNA, essentially removing dangerous microorganisms in the mask itself.
While standard disposable paper masks – typically made from layers of nonwoven polypropylene plastic microfiber – are also effective in stopping the spread of respiratory disease, they simply tend to trap the pathogens, and cannot be easily sanitized.
“In a hospital setting, these masks are placed in special bins and disposed of appropriately,” says Forró. “Using them in the wider world – where they are thrown in open bins and even left on the street – can turn them into new sources of contamination.”
The new material has yet to be specifically tested with SARS-CoV-2, but researchers are confident that these nanowire masks may be useful in combating the global pandemic, given the results they have seen with E. coli and DNA strands.
Two of the authors of the study have set up a startup called Swoxid, which will be the company that moves to take this invention into the world and develop the material as a commercial proposition. There are enough obstacles before any new invention can hit the market, but the team seems pretty gung-ho about their prospects.
“As of today, the technology we propose, exclusively under laboratory conditions, will allow the filter production capacity of about 100-200 m2 per week. This is enough to manufacture 40,000 – 80,000 reusable masks a month, “the researchers write in their study.
Such a best-case scenario can only take place after further development and research takes place, but the prototype of the team certainly seems interesting.
As our understanding of mask science evolves, experts will be better able to determine which masks stop viral drops most effectively – and with COVID-19 still very much with us, a mask that can actively destroy the virus would be very useful, if we can contain i.
The study was published in Advanced functional materials.
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