COVID-19 response - monitoring and possibly control of heat treatment of used PPE to deactivate virus

Hi all,

Ongoing effort to develop a heat-treatment protocol for PPE to make emergency re-use of masks, etc. safer. Ideally we need to place multiple temperature probes, in and around the PPE being treated to ensure it won’t get too hot / cold, and remains in required temperature band for required time period.

This is viable because unlike many pathogens this one is particularly susceptible to heat stress - e.g. 15 mins at 56°C in lab tests, and the method has had in-principle approval from postdoc microbiologist.

Go/no-go should be as clear as possible for staff under heavy stress.

Lots of info and threads available, I’ll put them in follow-up replies, incase spam checker gets grumpy with me.

Most hospitals have heating equipment which is suitable, but need extra monitoring to assure correct operation if at all possible.

Let me know if any questions!

Any help at all, including wiki editing (e.g. following references in threads, and adding to / organising wiki) most welcome - I’ve just about got steam coming out of my ears here.





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There is now initial proof of concept for this process from both Delft University of Technology and Stanford University see github wiki link above for links to papers.

It seems likely that in the developing world (if not more widely), improvised process monitoring will be required for this, and pi or similar, with multiple OneWire sensors, and e.g. a phone to provide the UI should be sufficient.

Any thoughts or feedback welcome!


Hello @tim, thanks for posting. Great initiative in these challenging times!
I’ve read through your github page and note your comments in this section:

  • Ideally add multiple temperature probes to this and automatically monitor to give a go / no-go.
    • Raspberry pi reading multiple Onewire sensors (commonly available encapsulated and prewired)
    • Reporting via an internal web server
    • Smart phone connected by wifi or USB to give readout (no need for a custom smartphone app)

I wonder if something like this might provide a lower cost simpler approach

Trying to keep components to a minimum. Power cycling the arduino could ‘reset the clock’ and the LCD backlight (if multi-colour) could be used to indicate a complete 15 minute >56C cycle, in addition to status printed on the LCD…

What do you think? Is that helpful?

I could prototype this here without too much difficulty, but will need to get @Gwil to bring me back components from the office as Im working from home & social distancing …

Components required:

That should make it very low cost (<£10)

Or maybe repurposing something like: but that would introduce complexities around WiFi, additional power requirements, requirement for a mobile phone, and interface development…

Or even not sure if this can validate that the temperature was maintained for the desired length of time, but there seems to be many similar products.

Hi Trystan, thanks for useful research and ideas! Several institutions (including one in Edinburgh) are planning more testing to try and determine the sensitivity of masks to temperature - hopefully these will give some indication of how much process monitoring is required (e.g. if max safe temp is 75°C, then this is a tough problem, OTOH if it’s 120C, then no problem). It may well vary widely between mask models. I’ll keep you posted with more details as I have them!

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Great, good initiative Tim!

just curiously would not UV work easier. that how the Chinese were disinfecting equipment room and what knot … they had for each quarantine room a UV light box and stuff was passed in and out of the room through there. , plus they used autonomously guided UV Light standards to make they way in and out of rooms. to disinfect the rooms before another patient when into it . it also seams the Americans hospital are using UV to disinfect masks as well. since they are in incredibly short on supply down there ( many hospitals as using bandanas instead of masks )

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Hello, yes UV does work, but the equipment to do-so may be scarce (particularly in the developing world). Stanford has published more work overnight, including testing with both.

Also I spoke to a microbiologist who said that whilst UV-C is great for surfaces, they use it on a daily basis, and was pessimistic about the ability of UV-C to penetrate to the full depth of the mask filter material, and also about material degradation, particularly after multiple cycles.

Updated Stanford data here:

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Quick update, still awaiting data regarding how tightly the temperature needs to be monitored, probably late this week / early next.

Some good news regarding the fight against COVID-19

research coming out of University of Manitoba on covid if you use autoclaves ( found in all hospitals) can recycle some n95 up to 10 times on pleated pleated version of mask. another option is vaporize hydrogen peroxide ( not all hospital have them) will work on all types… just if you were curious

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