Engineers Stress-Testing Disinfected N95 Masks for Reuse

The N95 respirator mask is often the first line of defense against COVID-19 for many medical professionals. University of Michigan  engineers have been working to address the current shortage by developing scalable, efficient ways to disinfect the masks, which are typically thrown out after one use. They're also testing if the masks still work and fit after repeated rounds of treatment, and stress testing the masks in what is essentially a small wind tunnel. One team is assessing the methods that best inactivate virus particles on N95 masks, and a second team is figuring out how many times masks can be treated by those methods and still retain their protective capabilities. Initial testing provides evidence that a combination of ultraviolet light and humid heat may work in disinfecting.

Transcript

00:00:09 CAPECELATRO >> So there's a steering committee that was put in place. It's called the COVID-19 Rapid Response Steering Committee. NARRATOR >> Battling potential shortages of personal protective equipment, three University of Michigan research teams are working together to recycle used N95 masks. CAPECELATRO >> The idea here is to address different needs from the hospital as they arise and these are needs that are deemed urgent. One of the first things that came about, was identified from the Health System, that they're going to be running very low on the N95 masks. NARRATOR >> Professors Herek Clack and Mirko Gamba are working to ensure that the masks still work after repeated decontamination treatments.

00:00:56 CLACK >> This mask is mounted in essentially a small wind tunnel and we take measurements upstream and downstream of the masks. NARRATOR >> They test these masks by running different sized particles through them and comparing results to what they would normally experience in a regular room atmosphere. GAMBA >> The idea is that this mask could actually be reused five, ten times before to it would be disposed, so over time we can monitor if they degrade in their effectiveness of capturing the particles. The process has to be scalable. There could be thousands, tens, hundreds of thousand throughout the

00:01:29 nation saved if this mask could be treated. CLACK >> The standard requires that no more than five percent of particles about this size penetrate. All but one of the masks we've tested have met that standard. If you look at a mask treated once, five times, and ten times, if we don't see an increase, then that gives us confidence that the mask really isn't being degraded by these sterilization processes. Before any outsourced masks get put into service we've been told to expect that they want to be tested in this apparatus so that we can be sure that they meet this 95% filtration efficiency and so we're making plans to grow our capacity to test masks beyond what we've got already.

00:02:16 CAPECELATRO >> It's literally life or death and so every day that we don't yet have a solution could potentially mean patients coming in that's not getting the care they need. Right now the focus is recycling N95 masks. We're already moving towards face shields. We know that ventilators are probably on the horizon. And so having a method in place so that we can quickly get the right people to solve the problem in the timeframe that we need it is 100% essential.