Public Health

Local sourcing of PPE: From 3D printing to thermoforming for masks

Sara Berg, MS , News Editor

Personal protective equipment (PPE) is in short supply across the country due to the demand from the COVID-19 pandemic. With a critical need for PPE, a mathematician in Hattiesburg, Mississippi answered a call from the medical community to address the mask deficit. As a director in the 3D printing lab at the University of Southern Mississippi, she was uniquely qualified to help create a solution.  

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When critically low on testing supplies for COVID-19, Hattiesburg Clinic in Mississippi partnered with community facilities to develop a solution. Following that same mindset, Hattiesburg Clinic and Forrest General Hospital teamed up with Anna Wan, PhD, an assistant professor of mathematics and director of The University of Southern Mississippi’s 3D printing lab Eagle Maker Hub, to create respirator masks and ventilator filters to meet the growing demands caused by COVID-19.  

Within just a few days, Wan successfully created 1,600 “Hub Masks” for physicians and other health professionals at Forrest General Hospital and Hattiesburg Clinic, said John Fitzpatrick, MD, a nephrologist and president of Hattiesburg Clinic, the largest private multi-specialty clinic in Mississippi and an AMA Health System Program Partner.  

Together with Wan, Hattiesburg Clinic and Forrest General Hospital were able to create a solution that addressed the potential shortage of PPE and ventilators. 

Initially, Wan wanted to test the “commonly shared Lowell 3D printed respirator mask” to assess the needs of physicians and other health professionals. However, “the commonly used material for Fused Deposition Modeling 3D printing, polylactic acid (PLA), was at the time limited in supply,” said Dr. Fitzpatrick.  

This was because it had “delayed shipping, potential faults to 3D printed parts without a stable annealing process, lack of complete sanitization solution for PLA, and it was not easy to create a seal around the face,” he said. 

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“Another problem was that these masks take a minimum of 5.5 hours to make,” said Dr. Fitzpatrick, adding that it led to the need to quickly come up with a different approach: Thermoforming masks from thin plastic sheets and adding an external facing flange to the mask design.  

“These masks made a much better seal when applied to the face, were more comfortable and could be made at a rate of 20 per hour. The material was also more readily available,” he said.  

Unfortunately, one problem remained for the initial prototypes. It was unclear what material would have N95 characteristics.  

“A local HVAC technician informed me that a MERV [Minimum Efficiency Reporting Value] rating of 16 translates to filtering out more than 95% of particles—hence the mask’s name,” said Dr. Fitzpatrick. “I procured a large filter containing MERV 16 material and brought it to Wan’s lab. We were excited that we may have found a solution.”  

Dr. Fitzpatrick asked Wan if she could print copies of ventilator parts if she had the original part to start. Knowing that this was a possibility, they met with Steven Stogner, MD, a pulmonologist and director of critical care at Forrest General Hospital. While there, they met with Brittany Coberly, PhD, director of respiratory therapy at the hospital, who was particularly familiar with N95 respirator masks after fires in Paradise, California caused her to wear them for three months while living there.  

After Wan asked if there was existing filter technology that she could use to redesign her mask, Dr. Coberly produced a filter used in ventilator circuits for patients at Forrest General Hospital. Immediately, Wan knew “she could redesign her mask to fit that filter,” said Dr. Fitzpatrick.  

“Within a day she had created a new prototype that was a perfect fit for the ventilator filter,” said Dr. Fitzpatrick. “It passed the N95 fit test in the lab.”  

After creation of this, Wan called the new respirator the “Hub Mask” because the ventilator filter is attached at the hub. The name also comes from being engineered in “The Hub City” of Hattiesburg, Mississippi.  

Within days, Wan was able to create more than 1,500 Hub Masks for staff at Forrest General Hospital and Hattiesburg Clinic. However, while these will be used as back up if existing N95 masks run out, “the filter is actually N99 rated,” said Dr. Fitzpatrick. 

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Since the creation of the Hub Masks, Wan and her team at the University of Southern Mississippi continue to work with Forrest General Hospital and Hattiesburg Clinic.  

Together they have “developed prototypes for snorkel masks, protective full body shields for patients during transportation and an Ambu bag ventilator,” said Dr. Fitzpatrick. “She has laser cut hundreds of face shields for health care workers.” 

“Combining Wan’s work with the production of cloth face masks and gowns by the Hattiesburg community, has reduced health care workers’ anxiety regarding potential personal protective equipment shortages in Hattiesburg as we face this crisis,” he said.  

The AMA has developed a COVID-19 resource center as well as a physician’s guide to COVID-19 to give doctors a comprehensive place to find the latest resources and updates from the Centers for Disease Control and Prevention and the World Health Organization. 

Additionally, the AMA’s COVID-19 FAQ will help physicians address patient concerns and offers advice on key issues such as how to conserve PPE.