Development, manufacturing, and preliminary validation of a reusable half-face respirator during the COVID-19 pandemic

Abstract

Introduction The COVID-19 pandemic has led to widespread shortages of N95 respirators and other personal protective equipment (PPE). An effective, reusable, locally-manufactured respirator can mitigate this problem. We describe the development, manufacture, and preliminary testing of an open-hardware-licensed device, the “simple silicone mask” (SSM). Methods A multidisciplinary team developed a reusable silicone half facepiece respirator over 9 prototype iterations. The manufacturing process consisted of 3D printing and silicone casting. Prototypes were assessed for comfort and breathability. Filtration was assessed by user seal checks and quantitative fit-testing according to CSA Z94.4–18. Results The respirator originally included a cartridge for holding filter material; this was modified to connect to standard heat-moisture exchange (HME) filters (N95 or greater) after the cartridge showed poor filtration performance due to flow acceleration around the filter edges, which was exacerbated by high filter resistance. All 8 HME-based iterations provided an adequate seal by user seal checks and achieved a pass rate of 87.5% (N = 8) on quantitative testing, with all failures occurring in the first iteration. The overall median fit-factor was 1662 (100 = pass). Estimated unit cost for a production run of 1000 using distributed manufacturing techniques is CAD $15 in materials and 20 minutes of labor. Conclusion Small-scale manufacturing of an effective, reusable N95 respirator during a pandemic is feasible and cost-effective. Required quantities of reusables are more predictable and less vulnerable to supply chain disruption than disposables. With further evaluation, such devices may be an alternative to disposable respirators during public health emergencies. The respirator described above is an investigational device and requires further evaluation and regulatory requirements before clinical deployment. The authors and affiliates do not endorse the use of this device at present.

A systematic review of passing fit testing of the masks and respirators used during the COVID-19 pandemic: Part 1-quantitative fit test procedures

“…The fit test exercises had a greater FF than resting exercises, according to the Baba et al study [ 104 ]. Anwari et al deemed "Failure" three of the fit test exercises, which involved bending, talking, and side-to-side movement [ 136 ]. Likewise, another research pointed out that extensive head and body movements could disrupt the adjustment and fitting of respirator [ 137 ].…”

Quality versus emergency: How good were ventilation fittings produced by additive manufacturing to address shortages during the COVID19 pandemic?

“…In usual situations, the manufacture of such devices is subjected to the recent EU regulation 2017/745 ( https://eur-lex.europa.eu/eli/reg/2017/745/oj ), which limits emergency production due to demanding quality control and risk management protocols. To the best of our knowledge, these regulatory concerns were frequently mentioned but rarely addressed formally by the numerous teams who have produced 3D-printed ventilation fittings and other respiratory-related devices during the first wave of the pandemic [ 27 – 30 ], and few initiatives have been successfully certified by local regulatory authorities [ 31 , 32 ]. If further sanitary crises occur, in potential cases of temporary adaptations of this regulation to overcome shortages, our results strongly suggest that strict quality control assessments should be maintained, managed by teams experienced in medical 3D-printing, to eventually obtain formal certification.…”

Quantitative Fit Test of a 3D Printed Frame Fitted Over a Surgical Mask: An Alternative Option to N95 Respirator

“…Some other alternatives to disposable N95 respirators can be reusable stop-gap respirators as alternatives made from 3D printing, silicone molding, and plastic extrusion [ 26 – 28 ]. Anwari et al [ 26 ] developed and did the preliminary testing of an open-hardware-licensed device, the “simple silicone mask” (SSM).…”

“…Some other alternatives to disposable N95 respirators can be reusable stop-gap respirators as alternatives made from 3D printing, silicone molding, and plastic extrusion [ 26 – 28 ]. Anwari et al [ 26 ] developed and did the preliminary testing of an open-hardware-licensed device, the “simple silicone mask” (SSM). The respirator originally included a cartridge for holding filter material; this was modified to connect to standard heat-moisture exchange (HME) filters (N95 or greater) after the cartridge showed poor filtration performance due to flow acceleration around the filter edges, which was exacerbated by high filter resistance.…”