Rechargeable N95 mask with a custom fit

In the fight against COVID-19, scientists from Berkeley Lab and UC Berkeley are developing an N95 quality assessment test; a rechargeable, reusable, anti-COVID N95 mask; and a 3D printable silicone molded mask mold. Credit: UC Berkeley

Scientists from Berkeley Lab and UC Berkeley have designed a rechargeable N95 mask that fits.

In the early days of the pandemic, amid all the uncertainty, one thing was certain: N95 masks – the personal protective breathing devices that filter viruses, bacteria and wildfire smoke – were in short supply. When materials scientists Jeff Urban and Peter Hosemann heard that a local HMO needed advice on N95 alternatives, they immediately knew what to do: make a better mask.

Hosemann called and discovered that the HMO’s doctors and inventory managers wanted to know what makes an effective antiviral mask, and how they could verify if the masks they found were actually good.

“It was helpful to learn what their needs were, and how we could complement and help support their mission,” Hosemann said. He holds titles as a faculty scientist in the Department of Materials Science at Lawrence Berkeley National Laboratory (Berkeley Lab) and Ernest S Kuh Chair in Engineering at UC Berkeley.

“Fortunately, Peter and I have just joined forces because we started working on similar ideas at the laboratory level,” said Urban, who runs the inorganic nanostructure facility at the Berkeley Lab Molecular Foundry.

Urban and Hosemann responded to a Berkeley Lab-wide call for research ideas in support of fighting COVID-19, which eventually led to their support by the National Virtual Biotechnology Laboratory (NVBL), a consortium of national laboratories for DOE with nuclear capabilities relevant to the threats posed by COVID-19, funded under the Coronavirus Aid, Relief, and Economic Security (CARES) Wet.

“We, like many others, saw the shortcomings in the PPE (Personal Protective Equipment) supply chain and even the functionality of what was available, and we felt that this was an important area to focus on,” said Urban. said.

If it protects you from COVID-19 or other viral infections, N95 masks are the gold standard. They are usually made of densely woven layers of polypropylene that filter at least 95% of very small particles in the submicron (millionths of a meter), including coronavirus particles and particles from veldfire smoke. This mishmash of fibers generates an electrostatic charge that attracts and traps virus particles.

But despite their excellent filter efficiency, N95 masks have their limits. For example, experts recommend not using N95 masks again, especially if you wear them all day. This is because we expel moisture from our mouths and lungs – and if we wear an N95 mask for a long time, the moisture eventually erodes the electrostatic charge on the virus-trapping fibers, Urban said.

Experts also say that an effective N95 mask should form a dense but comfortable seal around your face. Otherwise, even small gaps in virus particles can give easy access to your respiratory system through your nose and mouth.

Blueprint for a better N95 mask

Urban and Hosemann say their joint research effort is aimed at addressing such issues with long-term filter efficiency by designing and manufacturing a reusable silicone N95 machine with a rechargeable, mesh-active filter.

Anti-COVID N95 masks

UC Berkeley’s Jason Duckering wears a prototype of a rechargeable anti-COVID N95 mask. Credit: UC Berkeley

The wire mesh carries an electrostatic charge, which helps capture and neutralize virus particles, Hosemann explained. “This mesh filter can be recharged, and so the mask itself can be reusable, an important advantage,” he said. “The ultimate vision is to make a mask with a filter battery cartridge that you can charge and recharge overnight, like a cell phone.”

To deal with fit and PPE deficiencies, scientists are developing a 3D printable silicone mold for the body of the mask.

A metal wire embedded in the silicone casting allows the mask to conform to most faces.

And in the event of a PPE shortage, a 3D-printed form can allow anyone – from the DIY hobby – to deliver clerks at a school or hospital – to N95 silicone masks on demand and with short to make delivery times, Hosemann said.

“The combination of 3D printing and casting of simple parts is a powerful way to quickly produce unavailable PBT when the raw material is available,” he added.

The scientists also designed the silicone masks to connect with N95 filters or the rechargeable mesh filter.

When designing their reusable mask prototype, scientists also took into account that N95 masks and filters are often worn during manual labor. “When you do physical work, like many frontline workers, the ability to breathe more without compromising your health is an important feature of an ideal protective mask,” Urban said.

To test the impermeability of the mask prototype against small particle-sized particles, the scientists used fluorescent particle tests in collaboration with UC Berkeley, Evan Variano, a professor of environmental engineering, and Simo Mäkiharju, an assistant professor of mechanical engineering. The fluorescent particles monitor the distribution of particles in and around the manufactured masks, Hosemann said.

The scientists will use the same fluorescent nanoparticle technology for future filter efficiency tests in collaboration with Bruce Cohen of Berkeley Lab’s Molecular Foundry.

The 3D printable silicone mold and the rechargeable N95 filters are still in the early stages of R&D, but Urban and Hosemann say they are progressing fast. The scientists are developing an N95 on-site evaluation evaluation test for researchers and hospitals in the medical industry through the Molecular Foundry user program.

“It was very inspiring to see how national laboratory researchers can apply their expertise to understand pandemic issues, conceptualize solutions, communicate with future Molecular Foundry users and deliver prototypes, all within seven months,” said Deepti Tanjore, head of Berkeley Lab, said. the NVBL research effort for national laboratory production.

The scientists acknowledge the work of undergraduate student researcher Jason Duckering and research engineer Jeff Bickel in the UC Berkeley Division of Nuclear Engineering. “Jason and Jeff’s engineering skills played an important role in this effort,” Hosemann said.

The team, including postdoctoral fellows Chaochao Dun and Jaeyoo Choi, built the mask and section tests throughout the pandemic, starting in March.

“We are very excited to bring this new N95 user program for the development of rechargeable masks, 3D printable mask shapes and quality assessment section tests to Berkeley Lab’s Molecular Foundry,” said Urban. “It’s nice to know that what we’re developing will have an immediate impact on real-world applications that can help so many people.”

The Molecular Foundry is a DOE office for scientific users in Berkeley Lab.

This project is supported by the U.S. Department of Energy National Virtual Biotechnology Laboratory: a consortium of DOE National Laboratories with nuclear capabilities relevant to the threats posed by COVID-19, funded under the Coronavirus Aid, Relief, and Economic Security ( CARES) Act. .

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