Because the outbreak of COVID-19, there’s been a worldwide scarcity of face masks — notably, the N95 ones worn by well being care employees. Though these coverings present the very best stage of safety presently accessible, they’ve limitations. Now, researchers reporting in ACS Nano have developed a membrane that may be hooked up to an everyday N95 masks and changed when wanted. The filter has a smaller pore measurement than regular N95 masks, doubtlessly blocking extra virus particles.
N95 masks filter about 85% of particles smaller than 300 nm. SARS-CoV-2 (the coronavirus that causes COVID-19) is within the measurement vary of 65-125 nm, so some virus particles might slip by these coverings. Additionally, due to shortages, many well being care employees have needed to put on the identical N95 masks repeatedly, though they’re supposed for a single use. To assist overcome these issues, Muhammad Mustafa Hussain and colleagues wished to develop a membrane that extra effectively filters particles the scale of SARS-CoV-2 and may very well be changed on an N95 masks after each use.
To make the membrane, the researchers first developed a silicon-based, porous template utilizing lithography and chemical etching. They positioned the template over a polyimide movie and used a course of referred to as reactive ion etching to make pores within the membrane, with sizes starting from 5-55 nm. Then, they peeled off the membrane, which may very well be hooked up to an N95 masks. To make sure that the nanoporous membrane was breathable, the researchers measured the airflow charge by the pores. They discovered that for pores tinier than 60 nm (in different phrases, smaller than SARS-CoV-2), the pores wanted to be positioned a most of 330 nm from one another to realize good breathability. The hydrophobic membrane additionally cleans itself as a result of droplets slide off it, stopping the pores from getting clogged with viruses and different particles.