Although N95 face masks are quite effective at blocking transmission of the COVID-19-causing SARS-CoV-2 virus, they're also intended to be used only a few times at most. A new removable membrane, however, could make them much more reusable.
Led by Prof. Muhammad Mustafa Hussain, a team at Saudi Arabia's King Abdullah University of Science and Technology (KAUST) started with a thin film of a polymer known as polyimide. After a porous silicon template was placed over that film, a process called reactive ion etching was used to create an array of tiny pores within it.
The size of the pores ranged from 5 to 55 nanometers (nm) – this is considerably smaller than individual SARS-CoV-2 viruses, which range from 65 to 125 nm in width. In order to allow for sufficient breathability, those pores were placed no farther than 330 nm apart from one another.
The resulting membrane was shown to be highly effective at blocking the virus while still allowing the user to breath comfortably, adding to the protection already offered by the N95 mask itself. It's simply applied to the surface of the mask before each use, then just peeled off and disposed of afterwards.
And as an added bonus, because the membrane is hydrophobic (water-repelling), it causes droplets and other contaminants to roll off instead of clinging to its surface and clogging its pores.
There's currently no word on when the membrane may be commercially available.
A paper on the research was recently published in the journal ACS Nano.
Source: American Chemical Society