A feasible route for the design and manufacture of customised respiratory protection through digital facial capture

Abstract

The World Health Organisation has called for a 40% increase in personal protective equipment manufacturing worldwide, recognising that frontline workers need effective protection during the COVID-19 pandemic. Current devices suffer from high fit-failure rates leaving significant proportions of users exposed to risk of viral infection. Driven by non-contact, portable, and widely available 3D scanning technologies, a workflow is presented whereby a user’s face is rapidly categorised using relevant facial parameters. Device design is then directed down either a semi-customised or fully-customised route. Semi-customised designs use the extracted eye-to-chin distance to categorise users in to pre-determined size brackets established via a cohort of 200 participants encompassing 87.5% of the cohort. The user’s nasal profile is approximated to a Gaussian curve to further refine the selection in to one of three subsets. Flexible silicone provides the facial interface accommodating minor mismatches between true nasal profile and the approximation, maintaining a good seal in this challenging region. Critically, users with outlying facial parameters are flagged for the fully-customised route whereby the silicone interface is mapped to 3D scan data. These two approaches allow for large scale manufacture of a limited number of design variations, currently nine through the semi-customised approach, whilst ensuring effective device fit. Furthermore, labour-intensive fully-customised designs are targeted as those users who will most greatly benefit. By encompassing both approaches, the presented workflow balances manufacturing scale-up feasibility with the diverse range of users to provide well-fitting devices as widely as possible. Novel flow visualisation on a model face is presented alongside qualitative fit-testing of prototype devices to support the workflow methodology.

Facile method for 3D printing conformally onto uneven surfaces and its application to face masks

“…3 D. In the plot, the vapor was injected at t=2s and continued until t = 12 s. The measurements validated the rapid and huge amount of vapor leakage for 3D-printed rigid personalized face masks compared to face masks with the additional conformally printed soft seal. These results matched the statements of previous studies that the use of an additional flexible seal would improve the fit rate of a 3D-printed respirator and thus its air seal performance 25 , 37 .…”

“…The face mask prototypes were fastened onto the headform using two elastic bands, and two slots can be found on both the front of the face masks and the rear of the headform model to ensure the identical relative position of the face mask to the headform in each test. A similar test rig was adopted to assess the fit of the face mask in a study by Carter et al 37 .…”

“…However, rigid respirator designs can lead to higher contact loads while wearers move their faces 33 and cause skin damage after prolonged use time 34 . 3D printed rigid face masks with soft seals on the contour of the masks were designed and have been shown to have effects on both reducing wear discomfort and improving air seal performance by providing better compliance with the user’s face 35 – 37 . However, the manual processing required to fabricate the soft seals and assemble them onto the 3D-printed face mask frames can be time-consuming and costly.…”

Pandemic and Emergency Manufacturing Innovation: A Scientometric Analysis Using CiteSpace

“…Scholars had conducted studies on issues related to “emergency manufacturing” in the context of pandemics from different perspectives, including the development of new manufacturing technology, the optimization of manufacturing processes, 2 and so on, but there had not yet been systematic study on the impact of major epidemics on emergency manufacturing industry from a quantitative perspective. Based on this, the present study reviewed and summarized the current research results and developments in the field of emergency manufacturing.…”