The Barrow Innovation Center was developed by neurosurgery residents to tackle the unmet and unknown needs of the health care field. With this pandemic, we’ve been tirelessly working on products to help curb the personal protective equipment (PPE) supply shortages.

Our N95 substitute is a 3D-printed and silicone cast mask that seals around the face. It uses a 3M P100 filter and can be worn with other existing PPE.

What materials are needed?

The materials below are needed to produce the N95 replacement mask (manufacturer in parentheses):

• PLA 3D Printing Filament 
• Dragon Skin 10 Very Fast Silicone (Smooth-On)
• Ease Release 200 Silicone Mold Release (Mann Release Technologies)
• Elastic Band (Any)
• #212 O Ring (Any)
• Silicone Mold (Barrow)
• 4 two+ inch long 5/16" bolts and nuts. (or 2 C-Clamps)
• Reusable caulk tube
• Caulk tube gun (hand powered or electric)

What kind of filter is needed and where can I find them?

Our mask design includes a bayonet filter coupler which allows the user to use any number of filter cartridges. Specifically, we use 3M P100 filters which are approved by the National Institute for Occupational Safety and Health and have an emergency use authorization from the United States Food and Drug Administration. The coupler can also be further modified to attach to different filter cartridge types (e.g. screw on cartridges from Honeywell). 

Producing the mask:

1. 3D print a mask shell 
2. 3D print the corresponding two part mold
3. clean up each print
4. spray the mold with a silicone friendly mold release (we recommend the Smooth-on and Mann products)
5. Insert mask into the mold and lock into place using clamps, or the nuts and bolts. 
6. Mix 100mL of each part of silicone and pour into a caulk tube 
7. using the caulk gun, push silicone into the mold using the lower port
8. Insert until you see silicone coming through the exit port (higher port on the opposite side of the mold)
9. Cover both ports with clay plugs (or ear plugs)
10. let silicone set
11. unclamp tools and demold the mask
12. Clean up any excess silicone
13. Add straps
14. Assemble with filter coupler, O-ring, and filter cartridge

Remember to always check your equipment prior to use.

Fitting and Testing

Testing of these masks can be done in two steps: suction and saccharin (standard fit test).

• For suction, fit the finished mask to your face. Cover the coupler hole with your palm and inhale lightly. If there is a complete seal, you will not be able to inhale.
• The mask can undergo the same routine fit test as the standard FDA approved N95 surgical mask. This involves the standard saccharin nebulizers and testing hoods. This test and its details can be found on the OSHA website. Guidelines for Fit Testing This test and its details can be found on the OSHA website.