From the FB group Open Source COVID19 Medical Supplies - Entry #5:
EDIT: This stuff is hard! Bleach and hydrogen peroxide seem to be the best bets for DIY projects.
Hey guys, I've worked in medical device design and manufacturing for almost 20 years. I've also performed sterilization validations for many medical products. While I can't endorse any specifc methods used here, I wanted to provide some basic info and be available as a resource. I'll edit this post later to be more comprehensive
The most common methods are also probably the most out of reach to the DIY community:
Radiation sterilization (see ISO 11137)
- gamma irradiation (typically 25 kGy does the trick)
- electron beam radiation (typically 25kGy as well)
Gas exposure (see ISO 11135)
- ethylene oxide gas (this gas is very toxic so special chambers are needed)
Now for the more attainable methods:
- liquid chemical sterilization (ISO 14161)
- this is typically a peroxide of some sort but higher concentration than you can buy at the store
- moist heat sterilization aka autoclave (ISO 17665)
- dry heat sterilization aka your oven (ISO 20857)
The methods listed above are the most common but there are other 'non-traditional' methods as well.
The key to sterilization in med device is knowing your bioburden level going into the process. With this info you develop your cycle to achieve a sterilty assurance level (SAL) of 10^-6. This means an acceptable risk is that one out of a million devices sterilized might be non sterile. This limit is generally recognized by the FDA as acceptable for implants. For non implants it can be SAL 10^-3 or one in one thousand. The latter applies to things like face masks and tongue depressors and such.
UV sterilization isn't really a thing, it works on surfaces only. This is typically used in cell culture hoods with a built in bulb to keep the interior sterile but it does not give a similar assurance level as the med device sterilization methods.
I've worked primarily on implantable products which will require the above type methods. I would imagine that life saving equipment or components (like ventilator valves) would need a similar approach, but something like facemasks could be easily cleaned with surface disinfectants or UV exposure.
I am looking for any way to help so if you have questions please ask.
Kind regards, Ben
EDIT: This stuff is hard! Bleach and hydrogen peroxide seem to be the best bets for DIY projects.
Hey guys, I've worked in medical device design and manufacturing for almost 20 years. I've also performed sterilization validations for many medical products. While I can't endorse any specifc methods used here, I wanted to provide some basic info and be available as a resource. I'll edit this post later to be more comprehensive
The most common methods are also probably the most out of reach to the DIY community:
Radiation sterilization (see ISO 11137)
- gamma irradiation (typically 25 kGy does the trick)
- electron beam radiation (typically 25kGy as well)
Gas exposure (see ISO 11135)
- ethylene oxide gas (this gas is very toxic so special chambers are needed)
Now for the more attainable methods:
- liquid chemical sterilization (ISO 14161)
- this is typically a peroxide of some sort but higher concentration than you can buy at the store
- moist heat sterilization aka autoclave (ISO 17665)
- dry heat sterilization aka your oven (ISO 20857)
The methods listed above are the most common but there are other 'non-traditional' methods as well.
The key to sterilization in med device is knowing your bioburden level going into the process. With this info you develop your cycle to achieve a sterilty assurance level (SAL) of 10^-6. This means an acceptable risk is that one out of a million devices sterilized might be non sterile. This limit is generally recognized by the FDA as acceptable for implants. For non implants it can be SAL 10^-3 or one in one thousand. The latter applies to things like face masks and tongue depressors and such.
UV sterilization isn't really a thing, it works on surfaces only. This is typically used in cell culture hoods with a built in bulb to keep the interior sterile but it does not give a similar assurance level as the med device sterilization methods.
I've worked primarily on implantable products which will require the above type methods. I would imagine that life saving equipment or components (like ventilator valves) would need a similar approach, but something like facemasks could be easily cleaned with surface disinfectants or UV exposure.
I am looking for any way to help so if you have questions please ask.
Kind regards, Ben
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