By simulating inhalation, exhalation, coughs, and sneezes in the laboratory, the researchers found that non-woven fabrics used in most masks work well to demonstrate the concept.
Scientists have designed a new face mask with an anti-viral layer to deactivate the novel coronavirus, that can make the wearer less infectious. The idea is to modify mask fabrics with anti-viral chemicals that can sanitise exhaled, escaped respiratory droplets, according to the researchers from the Northwestern University in the US.
By simulating inhalation, exhalation, coughs, and sneezes in the laboratory, the researchers found that non-woven fabrics used in most masks work well to demonstrate the concept. The study, published on Thursday in the journal Matter, found that a lint-free wipe with just 19 per cent fibre density, for example, sanitised up to 82 per cent of escaped respiratory droplets by volume.
Such fabrics do not make breathing more difficult, and the on-mask chemicals did not detach during simulated inhalation experiments, the researchers said. “Masks are perhaps the most important component of the personal protective equipment (PPE) needed to fight a pandemic,” said Northwestern University’s Jiaxing Huang, who led the study. “We quickly realised that a mask not only protects the person wearing it but much more importantly, it protects others from being exposed to the droplets (and germs) released by the wearer,” Huang said.
Although masks can block or reroute exhaled respiratory droplets, many droplets and their embedded viruses still escape, the researchers said. From there, virus-laden droplets can infect another person directly or land on surfaces to indirectly infect others, they said.
The team aimed to chemically alter the escape droplets to make the viruses inactivate more quickly. After performing multiple experiments, the researchers selected two well-known antiviral chemicals: phosphoric acid and copper salt. These non-volatile chemicals were appealing because neither can be vaporised and then potentially inhaled, and both create a local chemical environment that is unfavourable for viruses.
“Virus structures are actually very delicate and ‘brittle’. If any part of the virus malfunctions, then it loses the ability to infect,” Huang said. The team grew a layer of conducting polymer polyaniline on the surface of the mask fabric fibres. The material adheres strongly to the fibres, acting as reservoirs for acid and copper salts.
The researchers found that even loose fabrics with low-fibre packing densities of about 11 per cent, such as medical gauze, still altered 28 per cent of exhaled respiratory droplets by volume. For tighter fabrics, such as lint-free wipes — the type of fabrics typically used in the lab for cleaning – 82 per cent of respiratory droplets were modified, they said.