Mass production can make custom PPE for healthcare workers

Research published in Nature demonstrated the feasibility of mass-producing personalized respiratory protection for healthcare workers with a comfortable and adjusted seal, suitable for nearly 90% of face shapes and sizes.

Providing adequate filtering PPE to frontline healthcare workers has been a major challenge since the start of the pandemic, and the key issue in providing effective protection is the need for a tight-fitting mask-to-face seal.

However, fitting the mask across the full range of face sizes and shapes has proven difficult, and failure of the “fit test” remains a frequently reported event. The areas of greatest variability, and where adjustment is most difficult to achieve, are around the nose, chin and cheeks.

Sophie Cox, who heads the Center for Custom Medical Device at the University of Birmingham, has been working with Birmingham researcher Luke Carter Owen Addison of King’s College London, to determine a manufacturing route that will allow the mass production of custom masks to as many people as possible.

The researchers captured 3D face measurements of 200 people, with mixed face shape, gender and origin to ensure their sample was representative of different face shapes. They then performed a statistical analysis which showed that a large proportion of people (87.5%) can be categorized into 9 patterns for a hard mask shell with an approximate fit to the person’s face.

Researchers achieved an airtight seal between the mask shell and the face using 3D-printed softened silicone, to provide nine mask prototypes. The fit of each of these prototypes was demonstrated using a new method to detect if steam could be escaping from the mask. The researchers then tested these designs on volunteer clinicians who had failed fit tests with commercially available half-mask respirators; each has passed standard qualitative fit testing using the closest prototype available.

“Doctors and nurses have consistently reported high rates of ‘failure to fit’ with mass-produced masks, leaving them at greater risk of the virus. Although the most desirable option would be a fully personalized “tailor-made” mask, this option would be prohibitively expensive. We have shown that the semi-custom approach, compatible with mass production, will provide a solution for almost 90% of people,” said Coxswain.

The University of Birmingham and King’s College London have filed patent applications based on the research.

The technology is marketed by MyMaskFit. The company is working with technology, design and manufacturing partners to bring custom face masks to market. It has developed a face scanning app for use on mobile devices that allows customers to scan face dimensions and securely transmit those measurements for rapid manufacturing. MyMaskFit will also pursue regulatory approval of custom, reusable medical-grade face masks.

Republished with kind permission from the University of Birmingham. Photo: Prototype of the mask. Credit: University of Birmingham.