DIY Laser-Cut Face Shields

Topic

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.

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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 28, 2020, there are now 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 that 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 enter the human body via the eyes [1]. A study that 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)[3], 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

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)
  • Laser-Cutting design (.dxf) file
  • 3D Printing design (.stl) file

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.

Laser-cutting:

  • Epilog Helix at 50 watt laser, Speed= 51% Power= 34% Frequency= 3500
  • clear plastic shield made from .020" (.5 mm) polycarbonate sheet.
  • 24" x 48"x .020" polycarbonate sheet can make 10 shields.
  • The cutting time is 75 seconds/2 shields
  • The original version uses PETG but here PET is used instead.

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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

Laser-cutting:

  • Epilog Helix at 50-watt power, cut at 55% speed, 50% power, and a frequency of 5000
  • Same plastic sheet as Design #1, but shield height was shortened from about 9.5" to just under 9" (this was done to make efficient use of material).
  • Blanks 9.6" x 18 were cut from 24" x 48"x .020" polycarbonate obtained locally (5 blanks = 10 shields)
  • Cutting time = 1 min, 5 seconds, per 2 shields

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3D Printing:

  • Time to print at .2mm layer height is just under 3 hours
  • Material used is about 10 meters (20% infill) of 1.75 mm filament

Design #3 (PET/G shield + 3D printed support, large)

This design is similar to Design #2, but it is physically larger

Laser-cutting:

  • Epilog Helix at 50-watt power, cut at 55% speed, 50% power, and a frequency of 5000
  • Same plastic sheet as Design #1 and #2, shield height was shortened from about 9.5" to just under 9" (this was done to make efficient used of material)

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3D Printing:

  • Time to print at .2mm layer height is just under 3 hours
  • Material used is about 16 meters (20% infill) of 1.75 mm filament.

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 [4][5]. Looking at the literature, the SARS virus from 2003 was deemed non-infectious after a similar heating protocol[6].

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

1. Clean your hands with soap and water or hand sanitizer before touching the mask.

2. Remove protective film from shield and head strap. The following picture illustrations have the blue film still on them so you can see the assembly with better clarity.

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3. Slide the top band with tabs into the corresponding rectangular slots on the shield to produce a curved shield surface.

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4. Daisy-chain together the elastic bands provided for the head strap. Next, feed each looped end of the elastic band through each side of the outer holes in the shield and around the adjacent tabs to secure them in place.

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5. Face shield mask assembly completed

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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 in Critical Care and Respiratory Care 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 Shields 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.

Author and Reviewing Information

Authors and Contributors:

Reviewed by:

  • Nadir Weibel, Ph.D., Professor of Computer Science, UC San Diego
    4/28/2020

References

  1. 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]
  2. 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]
  3. DtM-v3.1 Face Shield PPE, 3D printable headband NO LOGO, NIH 3D Printed Exchange, https://3dprint.nih.gov/discover/3dpx-013359
  4. 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
  5. 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]
  6. 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.