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Dr. Mike

DIY UV sterilization box for N95 masks and other medical equipment to fight coronavirus

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One of the biggest problems that health care workers have with the current COVID-19 coronavirus pandemic is the severe lack of PPE. 3D printing has helped with some items like face shields. One of the biggest shortages is with N95 masks. These masks have special, high-quality filters that simply cannot be 3D printed.

 

While 3D printing cannot make N95 masks, it can be used in part to build an UV light box that can help to disinfect/sterilize used masks and make them safer to reuse. I built such a device and gave it to my local hospital. I've documented the build process here in this video tutorial!
 

 

 

I've made the 3D printable files for the N95 mask holder available and free for download.

 

Materials for this build (As an Amazon Associate, we earn from qualifying purchases, thanks for your support!)

UV Lamps:

14" UV germicidal lamp (may be sold out):
Alternative 60W LED UV lamp w standard E26/E27 socket:
Another alternative 60W UV LED lamp :
E26/E27 light socket (needed for 60W lamps):

 

Other supplies:

Brinks digital timer
Heavy Duty aluminum foil
Gorilla glue
Machine screws and nuts (use #6)
Washer set
Adhesive velcro-type tape
Hook and loop cable ties
Large cardboard boxes
Packing tape
White spray paint
Silver spray paint

 

Please consider making a similar box for your local health care facility that is battling coronavirus!

 

Disclaimer: Nothing in the video should be interpreted as medical advice. This isn't an FDA-approved method of sterilizing or disinfecting medical equipment. Use appropriate care when working with UV light.

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It's an innovative solution that can be put into practice during this crisis, as it can be considered when there is a shortage of FFR.

 

The CDC puts it as an option (although it needs more research) when there is a crisis, some studies guarantee that the quality of the material may or may not be affected depending on the dose and the model of facial mask used.

 

Nebraska Medicine has implemented a protocol for UV irradiation of N95 respirators in the context of the COVID-19 pandemic based on the dose generally needed to inactivate other single-stranded RNA viruses on surfaces: 

 

Lowe JJ, Paladino KD, Farke JD, et al. N95 Filtering Facepiece Respirator Ultraviolet Germicidal Irradiation (UVGI) Process for Decontamination and Reuse

https://www.nebraskamed.com/sites/default/files/documents/covid-19/n-95-decon-process.pdf?date=03252020

 

These are some interesting studies that I would like share with all of you:

 

Lindsley, W. G., Martin Jr, S. B., Thewlis, R. E., Sarkisian, K., Nwoko, J. O., Mead, K. R., & Noti, J. D. (2015). Effects of ultraviolet germicidal irradiation (UVGI) on N95 respirator filtration performance and structural integrity. Journal of occupational and environmental hygiene, 12(8), 509-517.

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4699414/

 

Mills, D., Harnish, D. A., Lawrence, C., Sandoval-Powers, M., & Heimbuch, B. K. (2018). Ultraviolet germicidal irradiation of influenza-contaminated N95 filtering facepiece respirators. American journal of infection control, 46(7), e49-e55.

https://www.ncbi.nlm.nih.gov/pubmed/29678452

 

Heimbuch, B. K., Wallace, W. H., Kinney, K., Lumley, A. E., Wu, C. Y., Woo, M. H., & Wander, J. D. (2011). A pandemic influenza preparedness study: use of energetic methods to decontaminate filtering facepiece respirators contaminated with H1N1 aerosols and droplets. American journal of infection control, 39(1), e1-e9.

https://www.ncbi.nlm.nih.gov/pubmed/21145624

 

Also, you can  learn more about decontamination from the CDC here:

https://www.cdc.gov/coronavirus/2019-ncov/hcp/ppe-strategy/decontamination-reuse-respirators.html

 

Have you used this technique? share your experience with us!

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Careful with assumptions about reflectivity of aluminum foil and UV-C.  The most optimistic source I found reported 73%.  I also saw about 20% for aluminum in a study from 1929.  Shorter wavelengths in the band yielded worse reflection performance.

 

I'm using a fish tank UV-C bulb.  Didn't bother with aluminum foil (yet).  I just flip to cook each side.

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19 hours ago, Dr. Mike said:

One of the biggest problems that health care workers have with the current COVID-19 coronavirus pandemic is the severe lack of PPE. 3D printing has helped with some items like face shields. One of the biggest shortages is with N95 masks. These masks have special, high-quality filters that simply cannot be 3D printed.

 

While 3D printing cannot make N95 masks, it can be used in part to build an UV light box that can help to disinfect/sterilize used masks and make them safer to reuse. I built such a device and gave it to my local hospital. I've documented the build process here in this video tutorial!
 

 

 

I've made the 3D printable files for the N95 mask holder available and free for download.

 

Materials for this build (As an Amazon Associate, we earn from qualifying purchases, thanks for your support!)

UV Lamps:

14" UV germicidal lamp (may be sold out):
Alternative 60W LED UV lamp w standard E26/E27 socket:
Another alternative 60W UV LED lamp :
E26/E27 light socket (needed for 60W lamps):

 

Other supplies:

Brinks digital timer
Heavy Duty aluminum foil
Gorilla glue
Machine screws and nuts (use #6)
Washer set
Adhesive velcro-type tape
Hook and loop cable ties
Large cardboard boxes
Packing tape
White spray paint
Silver spray paint

 

Please consider making a similar box for your local health care facility that is battling coronavirus!

 

Disclaimer: Nothing in the video should be interpreted as medical advice. This isn't an FDA-approved method of sterilizing or disinfecting medical equipment. Use appropriate care when working with UV light.

Fantastic idea Dr. Mike, thanks for sharing and thanks to the entire medical community who are on the front lines!

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3 hours ago, Bill Michaelson said:

Careful with assumptions about reflectivity of aluminum foil and UV-C.  The most optimistic source I found reported 73%.  I also saw about 20% for aluminum in a study from 1929.  Shorter wavelengths in the band yielded worse reflection performance.

 

I'm using a fish tank UV-C bulb.  Didn't bother with aluminum foil (yet).  I just flip to cook each side. 

 

Thanks for the comment. This source reports aluminum reflectivity at 248nm of 92.6%. This study specifically looked out household aluminum foil and is reporting a total reflectivity of between 80 and 90% in the UV range. Here is another publication that shows reflectance in the low 90% range for aluminum between 200 and 500nm. All are pretty consistent with the numbers for UV at around 245 nm which is that wavelength used in this project. I think it is safe to conclude that the reflectivity is probably adequate for this project.

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12 hours ago, Dr. Mike said:

 

Thanks for the comment. This source reports aluminum reflectivity at 248nm of 92.6%. This study specifically looked out household aluminum foil and is reporting a total reflectivity of between 80 and 90% in the UV range. Here is another publication that shows reflectance in the low 90% range for aluminum between 200 and 500nm. All are pretty consistent with the numbers for UV at around 245 nm which is that wavelength used in this project. I think it is safe to conclude that the reflectivity is probably adequate for this project.

Great references, thanks.  It is reassuring.  Still, I would be careful about stating what is "safe...for this project" in light of the potential consequences for oversight.  I'm actually less worried about the reflectivity of aluminum than I am about obscuration of virus particles embedded within the layers of the filter fabric.  Grandma used to beat the rugs in the sunshine to get them clean.  Maybe some ultrasonics and a wind tunnel bathed in UVC...

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5 hours ago, Bill Michaelson said:

Great references, thanks.  It is reassuring.  Still, I would be careful about stating what is "safe...for this project" in light of the potential consequences for oversight.  I'm actually less worried about the reflectivity of aluminum than I am about obscuration of virus particles embedded within the layers of the filter fabric.  Grandma used to beat the rugs in the sunshine to get them clean.  Maybe some ultrasonics and a wind tunnel bathed in UVC...

I hear you Bill. Thanks for your great comments. I think it is important to consider what the alternative it, which is nothing. Right now in my area the ICU docs report to me that they are reusing the same N95 mask for an entire week without any kind of cleaning or sanitation whatsoever. What we are trying to do is provide a solution that is cheap and easy to implement, and while not optimal, better than the alternative which currently is nothing.

Angel provided some great references in his post above, including this one to CDC guidelines. This UV irradiation as a "crisis standard," which is guess means something that would be done in a crisis but not otherwise.  You are correct, UV will not penetrate, but it will potentially eliminate surface contamination and transmission should the provider be handling the mask. This article from the New England Journal of Medicine concluded that the SARS-CoV-2 virus is stable on cardboard, the best analog for the material in the mask, for 24 hours. So, in theory any particles trapped deep within the mask will be inactivated in that time even without UV. Surface contamination is what is more worrisome because the mask is handled both in putting on and taking off, and that could provide the potential for virus spread. 

 

Now that I am thinking about it, when I come out of a COVID patient room I usually take my gloves off first, then gown, then faceshield, then mask, then I gel my hands. But, in theory, by handling the mask at the end I could be contaminating my hands, thus leaving the gel as the only precaution against infection spread. Maybe we should be UV zapping our masks after every use instead of just at the end of the day? It only takes 5 minutes.

 

It's got me thinking. Anyone else have thoughts on the matter?

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Like the Idea and ordered printed double racks for n95 masks my question is what is the height of double rack?

 

Thanks

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