But people should not breathe the spray directly, and should not use it in layers of fabric that sit closest to the mouth, Lustig says. “But multiple layers will be effective, and if you at least have one or two layers that are hydrophobic, you’re going to get pretty good protection.” “With many kinds of cotton, one or two layers won’t work,” he says. That’s one way to turn a fabric into a decent water-repelling barrier, Lustig says. The team also tested cotton coated with Scotchgard, a commercial fabric and upholstery protector that repels water. Photos by Matthew Modoono/Northeastern University The best water-repellent layers to add in those combinations involve nonwoven polypropylene-Lustig’s team tested OLY-Fun fabric-and materials consisting of polyester and polyaramid, a blend used in lab coat fabric.ĭoctoral student Devyesh Rana measures the concentration of sprayed fluorescent nanoparticles (virus simulant) through fabrics onto glass slides in the Interdisciplinary Science and Engineering Complex. The findings show that absorbent layers that can stop coronavirus particles with the same or higher efficiency of an N95 mask include those using terry cloth, quilting cotton, and flannel. “There was a lot of trial and error about what kind of flow rates we should use, what kind of concentrations of nanoparticles, and how quickly the nanoparticles should be sprayed.” “You’re also breathing through the mask, so we had to replicate that in a physically and biologically meaningful way,” Lustig says. The tests also created different changes in airflow to account for the kind of dynamics a wearer creates by breathing, which helps viral particles pass through a material. Lustig’s team dispersed the nanoparticles in water and then sprayed that substance into the air to emulate a coughing and a sneezing from someone carrying the virus. The coronavirus gets its name from a set of crown-like spikes that surround its tightly packed genetic material. That combination of layers, in addition to a snug fit around the face and proper physical distancing, can make for a significant defense system, Lustig says.Ī particle of SARS-CoV-2 is no larger than a white blood cell or a light dust particle, which human eyes can’t see without a microscope. If the liquid wets the fabric, it can move viral material through it. One of the most important aspects of how to lay fabric that can block viral particles is to combine materials that have enough fibers to increase their chances of trapping, or absorbing, germs.Īnother key part of that puzzle is to use at least one layer with hydrophobic properties, which would repel aqueous substances such as respiratory droplets from someone’s airway and prevent them from passing through the mask. “But no one had really asked the question of how many layers it would take for cotton, for example, to be as good as an N95.” “Most fabrics aren’t as good as the official, certified N95 respirators.” Lustig says. The trick, Lustig says, is that the fabrics must be layered tactically. And Lustig, an associate professor of chemical engineering at Northeastern, trusts it because he and his team tested those materials in the lab.Īfter testing how nanoparticles penetrated more than 70 combinations of fabrics, the team found several combinations of common materials that can be as effective at blocking coronavirus particles as N95s-or better. His mask consists of a pair of layers of terry cloth. Photo by Matthew Modoono/Northeastern Universityīut when Steve Lustig goes out for a walk, he covers his face with a homemade mask that has the same ability to stop viral particles as an N95. Steve Lustig is an associate professor and the associate chair of research in chemical engineering at the College of Engineering at Northeastern.
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