A team at Sandia National Laboratories has developed a faster and more comprehensive way to test personal protective equipment, or PPE. The basic principle: modeling a device to fit the human form and human behavior.
When COVID-19 hit, PPE testing became an urgent necessity. In March 2020, when the country was on lockdown, many people turned to Sandia for support in testing PPE. They were trying to bring new masks to market, provide quality assurance for imported masks, and veterinary cleaning processes for re-use of single-use PPE.
Whether we use in-house or commercial filter testing systems, we have found that the testing process is time-consuming and not as efficient as it could be.”
Michael Omana, aerosol scientist at Sandia
The team, which includes engineers Todd Barrick and Brad Salzbrenner, was determined to find a better solution. They were trying to come up with ways that respirators could be tested quickly, rather than destructively, and to introduce other testing options, including going beyond testing the filter material.
The old way of testing
The current method of testing PPE involves attaching a mask to a flat plate in a box, using hot wax or putty, and then introducing a test aerosol to measure penetration levels. To receive certification from the National Occupational Safety Institute, 20 masks of the same type must be tested. This turned out to be time consuming. During the pandemic, this led to a huge backlog of tests for respirator production.
However, the team said that time is only one problem. The current process does not take into account other factors when using a mask.
“All you’re doing is testing the filter media itself,” Barrick explained. “It doesn’t test the geometry, how the respirator fits the face, how it goes on and off repeatedly, how the straps work, how the bridge of the nose performs, how the mask can be worn over time.”
There was also the issue of reusing PPE. With such a worldwide shortage, frontline workers have been forced to reuse disposable respirators. However, there was no standard method for testing mask reuse.
“I think there’s a lot of lessons learned when everybody suddenly looked at what the industry standards were,” Omana said.
The team had a new idea to speed up the process and make it more efficient. They started by creating a model of a human face that could be loaded into a commercial filter test system.
“We wanted faster testing and to look at more features, such as how the mask fits the face,” Salzbrenner said. “We used 3D printing capabilities to make it more flexible, like skin.”
Once the mask is attached to the form, the tester applies pressure to ensure an airtight seal and then introduces the aerosol.
But the team agreed that more could be done. Current testing standards do not take into account how a real person might wear a mask and the gaps or flaws a mask might have in real-world conditions. So they developed a more sophisticated version using a full human head.
Once the mask is attached, the entire head is placed in an airtight box, which is then placed into the machine and tested, allowing for a more natural flow of air over the mask and what they say is a more realistic picture of how the mask works .
The mechanical engineers on the team then took things a step further to help address the reuse of PPE, something for which there is currently no testing standard.
“We developed the camera version to automate donning and doffing (putting on and taking off an item) to test respirator function over time, a predominant factor in mask wear. It also mimics how the mask is placed on the face and shows you all the gaps that air and particles can get through,” Salzbrenner said.
The team said this can be used in addition to other testing models they have created or developed to be an all-in-one tester. All of this would be a major advance in the way PPE is tested in the US, as well as in other countries.
“I call it holistic testing,” Omana said. “It takes into account all aspects of the mask. Aerosols are like electricity and take the path of least resistance. Even if the filter media is performing perfectly, if another sub-component fails, the PPE can become useless. Current test standards do not quantitatively test PPE in a real-world capacity. This emulates the use of PPE in the real world.”
The team is now working to further test their approach with the help of $100,000 in funding from Sandia’s Technology Maturation Program. The goal is to license the science to a company that can produce it on a commercial scale. This is part of Sandia’s technology transfer initiative.
Necessity is the mother of invention
The saying “Necessity is the mother of invention” is no more true than this case. This invention was created during one of the most impactful pandemics in history, at a time when countless lives were at risk. And as many times before, when the world has a problem, those at Sandia try to deal with it.
“Without the diverse capabilities of the people at Sandia, a project like this would not happen,” Salzbrenner said. “If you look at the backgrounds of every single person on this team, everyone comes from a different discipline or walk of life. It was a combination of all these people who made these things happen.”
“As a national laboratory, we are fortunate to have some of the brightest minds, and with this experience, we felt it was our responsibility to do something to help the community,” Barrick added.
The team said one of the best parts of this project is that it happened organically.
“Everybody just jumped in to help,” Barrick said. “When we needed an answer, someone would say, ‘I know who can answer that.’ We would contact that someone and they would get involved. The amazing thing about it is that people donated their time. People worked harder than they were asked to help solve this problem. It was truly out of the goodness of their hearts. It was a call to action.”
DOE/Sandia National Laboratories