• David H Ballard, Udayabhanu Jammalamadaka, Kathleen W Meacham, Mark J Hoegger, Broc A Burke, Jason A Morris, Alexander R Scott, Zachary O'Connor, Connie Gan, Jesse Hu, Karthik Tappa, Richard L Wahl, and Pamela K Woodard.
• Mallinckrodt Institute of Radiology, Washington University School of Medicine, 510 S. Kingshighway Blvd, Campus Box 8131, St. Louis, MO 63110. Electronic address: davidballard@wustl.edu.
• Acad Radiol. 2021 Feb 1; 28 (2): 158-165.

Rationale And ObjectiveThree-dimensional (3D) printing allows innovative solutions for personal protective equipment, particularly in times of crisis. Our goal was to generate an N95-alternative 3D-printed respirator that passed Occupational Safety and Health Administration (OSHA)-certified quantitative fit testing during the COVID-19 pandemic.Materials And Methods3D printed prototypes for N95 solutions were created based on the design of commercial N95 respirators. Computed tomography imaging was performed on an anthropomorphic head phantom wearing a commercially available N95 respirator and these facial contour data was used in mask prototyping. Prototypes were generated using rigid and flexible polymers. According to OSHA standards, prototypes underwent subsequent quantitative respirator fit testing on volunteers who passed fit tests on commercial N95 respirators.ResultsA total of 10 prototypes were 3D printed using both rigid (n = 5 designs) and flexible materials (n = 5 designs), Prototypes generated with rigid printing materials (n = 5 designs) did not pass quantitative respirator fit testing. Three of the five prototypes with flexible materials failed quantitative fit testing. The final two prototypes designs passed OSHA-certified quantitative fit tests with an overall mean fit factor of 138 (passing is over 100).ConclusionThrough rapid prototyping, 3D printed N95 alternative masks were designed with topographical facial computed tomography data to create mask facial contour and passed OSHA-certified quantitative respiratory testing when flexible polymer was used. This mask design may provide an alternative to disposable N95 respirators in case of pandemic-related shortages. Furthermore, this approach may allow customization for those that would otherwise fail fit testing on standard commercial respirators.Copyright © 2020 The Association of University Radiologists. Published by Elsevier Inc. All rights reserved.

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