UAB’s School of Engineering creates HEPA filters for PAPR machines

UAB’s School of Engineering continues to move forward with development of personal protective equipment.

Joseph Moore of UAB Engineering, holding a prototype of the filter reservoir, wears a hood during a fit test for a 3d printed filter reservoir that he designed and created for ventilators UAB’s School of Engineering continues to move forward with development of personal protective equipment. Photography: Lexi CoonDue to a high demand for personal protective equipment, the University of Alabama at Birmingham School of Engineering has partnered with the State of Alabama to develop High-Efficiency Particulate Air filters for renovated Power Air-Purifying Respirator machines.

PAPR machines are personal protective equipment items that allow people to breathe freely in heavily polluted areas. The devices contain both a motorized fan and filter, which are strapped to the user’s lower back. The fan pulls in surrounding air through a HEPA filter and blows the clean air through a hose to a sealed face mask.

The State of Alabama allocated 30 discontinued PAPR machines to UAB Hospital, but the hospital was unable to use the machines because the manufacturer no longer makes the HEPA filter for the product.

Emily Boohaker, M.D., associate chief medical officer, UAB Quality and Patient Safety, reached out to the UAB School of Engineering to see if someone could create filters that would work with the devices.  

Joseph Moore, a 2017 electrical and computer engineering graduate who now works for the UAB Engineering and Innovative Technology Development, agreed to take on the project.  

“We got lucky and were able to find a filter that had very similar dimensions to the original PAPR filter,” Moore said. “Using CAD modeling and a 3D printer, I was able to reverse-engineer the housing that the filter mounts to.”

Moore, who has extensive experience with 3D printing going back to his undergraduate days, says part of the challenge was creating the air-tight seal between the filter and the filter housing, making sure all pulled air passes strictly through HEPA material. To create that, he needed a special kind of printer.

“We were able to use a form-cell — an automated network of several SLA printers at Jacksonville State University,” Moore said. “We were able to print the housing in two halves that could be fitted together, and required little extra work to have a finished and sealed plastic part.” 

Bill Mayfield and Matthew Mayfield put the 3d printed filter reservoir into the vetinlator for a fit test as Joseph Moore looks onBill Mayfield and Matthew Mayfield put the 3d printed filter reservoir into the vetinlator for a fit test as Joseph Moore looks on. Photography: Lexi Coon
The housing Moore designed is printed in two halves, which are fitted together around the HEPA material, given an extra seal with a non-toxic, food-grade epoxy, and then left to cure overnight. After initial flow tests proved successful, he began printing additional units, producing up to 3.5 units per day.

Moore and his team completed the first prototype, and since passing flow tests, have now delivered nine units to the hospital team.

“This prototype filter is working well in these powered, air-purifying respirators, providing us additional high-level personal protective equipment for our front-line clinical providers,” said Bill Mayfield, manager, Emergency Preparedness, UAB Medicine.