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This document outlines a solution for DIY Face Shields shortage during the COVID-19 pandemic. Specifically, the focus is on fabrication using laser-cutters and sterilization on face shields.
Disclaimer
This product is a face shield. Materials that contact the body are polycarbonate and rubber bands. This face shield does not contain materials that will cause flammability. Use this face shield with appropriate personal protective equipment per your institution’s standards.
This device has not been tested or qualified for any of the following uses: to prevent or reduce infection or related uses; for antimicrobial or antiviral protection; for radiation protection. It does not provide particulate filtration. Not intended for use in surgical settings. Nor has this device been approved by any local, state, or federal agency, including the FDA. This device has not been disinfected or cleaned. Non-sterile.
The Regents of the University of California makes no claims regarding the safety and efficacy of this product. This product is delivered without warranty of any kind, express or implied, including without limitation any warranty of title, merchantability, or fitness for a particular purpose. Use it at your own risk.
Background
As of April 29th 2020, there are 1 million COVID-19 cases in the United States and 50,000 deaths. The shortage of proper PPE is still an issue within hospitals across the United States. Most notably, N95 respirators and surgical masks have been scarce and are often re-used. However, another piece of disposable PPE which is commonly used is the face shield.
The face shield does not protect against any aerosol, but does protect against projectile droplets that can be expelled via a cough or sneeze. The face shield provides an additional form of an open barrier. For example, it prevents droplets from getting into one’s eye, and can add protective value with the absence of safety goggles. As more data is gathered about COVID-19 it seems that covering one’s mouth and nose are not the only parts of the face that should be protected as there is some evidence that SARS-CoV-2 can be enter via the eyes[1].
A study which simulated coughs from COVID-19 patients using a UV visible dye shows that the use of a face shield, or in their case a surgical mask with a shield visor, is important to protect against droplets landing on one’s face[2].
Noting the shortage of face shields and their importance in adding an extra layer of protection for healthcare workers, it is crucial that more face masks are produced. In turn, an increase in available face shields can keep healthcare workers safe, and further prevent the spread of COVID-19 amongst healthcare workers treating COVID patients.
Product Description
We have designed three different polycarbonate face shields that use PET (Polyethylene terephthalate) or PETG (Polyethylene Terephthalate Glycol-modified) a thermoplastic polyester that provides significant chemical resistance, durability, and excellent formability for manufacturing.
One design only uses PETG and is assembled using regular rubber or elastic bands. The two other designs also entail a 3D printed headgear and lower guard printed in PLA
Our designs are a modification of the original design created by the 3D printer manufacturer PRUSA, a Polish company that has been working with the Polish health department to tweak the original design. A similar design has recently been tested and recommended for clinical use by the US National Institute of Health (NIH), although it has not been approved by the FDA.
Clinical Applicability and Buy-In
We have received positive feedback to continue making these DIY Face Shields from top leadership within UC San Diego Health Systems in Critical Care and Pulmonary Care. If approved by the healthcare systems, these face shields can be effective for patient care.
Materials & Methods
Fabrication Machines
All three designs below have been created using the following machines
Laser engraver Epilog Helix, 24" x 18"
3D printer PRUSA
Plastic Shields Material
The shields are made using 0.5 mm thick PETG.
4ft x 8 ft sheets were cut into 48" x 16” strips, yielding 6 strips per 4’ x 8’ sheet.
Each strip is further cut into two 16in x 18in blanks and one 16” x 12” blank.
→ This shearing for 30 4’x8’ sheets takes 5.0 hours.Total time to cut the 16in x 18in blanks is just under 2 min (2 shields)
Total time to cut the 16in x 12in blank is just under 1 min (1 shield)
Total time estimate for 1 shield: 3.5 min
Material cost = $1.15/shield (for 900 shields)
Note: while the laser is cutting, the operator removes cutouts from the shields. While removing the shields, they are inspected and placed in lots of 5 into seal-able bags along with 5 size #33 rubber bands for each shield.
Design #1 (PET/G shield and band strip)
This design uses 2 separately laser cut parts (shield plus band strip) that are easily assembled.
Design #2 (PET/G shield + 3D printed support, small)
This design uses the same material and overall technique as Design #1 for the shield, a top and a bottom support, both 3D printed with PLA. Physically smaller of Design #3
Design #3 (PET/G shield + 3D printed support, large)
This design is similar to Design #2, but it is physically larger
Reusing Face Shields
With the shortage of supplies, effective reuse of PPE would be ideal. However, with reusing PPE such as face shields what is important to keep in mind is that the PPE has to be effectively cleaned.
Specifically for face shields, this can be done via wipes such as Clorox wipes or Cavi Wipes. Based on information from two different studies, it is effective to heat face shields at 70C for 30 minutes. One of the two data sets uses E.Coli as a protocol to test sterilization methods. However, seeing that E.Coli are bacteria and SARS-CoV-2 is a virus this raised some issues that were later resolved . Looking at the literature, the SARS virus from 2003 was deemed non-infectious after a similar heating protocol.
With this in mind, it is possible to heat face shields for reuse in blanket warmers commonly found in hospitals at 70C for 30 minutes. Most blanket warmers should go up to this temperature.
Assembly of recommended Face Shield #1
Summary
The technique we introduced here allows anyone who has access to PET/PETG and a laser-cutting machine to produce high-quality face masks. Although access to a 3D printer allows the production of 2 additional models, the laser-cutting-only methods have been reviewed and deemed acceptable by healthcare experts at UC San Diego. While this solution is not FDA-approved, nor has it been approved by UC San Diego Health for any clinical use, it can provide good protection from droplets produced during coughing and/or sneezing episodes by patients positive with Coronavirus.
The described Face masks can be produced at low cost and are easy to assemble and can be produced at scale, hopefully helping those clinical and non-clinical populations that are in need of PPE, especially while caring for COVID-positive patients.
References
- Wu P, Duan F, Luo C, et al. Characteristics of Ocular Findings of Patients With Coronavirus Disease 2019 (COVID-19) in Hubei Province, China. JAMA Ophthalmol. 2020. [PMID:32232433]
- Lockhart SL, Naidu JJ, Badh CS, et al. Simulation as a tool for assessing and evolving your current personal protective equipment: lessons learned during the coronavirus disease (COVID-19) pandemic. Can J Anaesth. 2020. [PMID:32221852]
- DtM-v3.1 Face Shield PPE, 3D printable headband NO LOGO, NIH 3D Printed Exchange, https://3dprint.nih.gov/discover/3dpx-013359
- Price A, Chu L. Addressing COVID-19 Face Mask Shortages. Stanford Medicine: Anesthesia Informatics and Media Lab, https://aim.stanford.edu/covid-19-evidence-service
- Viscusi DJ, Bergman MS, Eimer BC, et al. Evaluation of five decontamination methods for filtering facepiece respirators. Ann Occup Hyg. 2009;53(8):815-27. [PMID:19805391]
- Duan, S. M., X. S. Zhao, R. F. Wen, Jing-jing Huang, G. H. Pi, S. X. Zhang, Jun Han, S. L. Bi, Li Ruan, and Xiao-ping Dong. "Stability of SARS coronavirus in human specimens and environment and its sensitivity to heating and UV irradiation." Biomedical and environmental sciences: BES 16, no. 3 (2003): 246-255.
Author and Reviewing Information
Authors and Contributors:
Joe Mayer (Principal laboratory Mechanician, Kimberly Prather research group member - CAICE)
Shiv Patel (UCSD Simulation Training Center and Weibel Lab)
Reviewed by: Nadir Weibel, Ph.D., Professor of Computer Science, UC San Diego
Review Date: 4/28/2020