Sterilise printed objects

Has anyone managed to make a sterilisable object on a reprap - if so what materials (and where can you get them) and processes did you use as autoclaving and most surface sterilising seems to be out due to issues with the plastics melting or dissolving.

Ideally I think I am looking for something that would survive an autoclave, alcohol and the odd bit of bleach. Any ideas? - Possibly Polycarbonate.

The follow up question is, what would you need to upgrade over a standard reprap kit (thinking reprap pro Huxley here).

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So far the ideal plastic appears to be Polyphenylsulfone (PPSF/PPSU) but I may have swallowed someones marketing hype, but it seems to run at the $400 per 1litre, and only available in canisters for a specific printer....

Edited 3 time(s). Last edit at 05/12/2013 09:19AM by squeeks.

I haven't tried sterilizing anything printed yet, but a typical autoclave runs around 250 degrees F.
I'm pretty sure PLA would absorb the steam and break.

For plastic things you usually sterilize with EtO (Ethylene Oxide) or an ionizing radiation burst.
You have to make sure the plastic is compatible with the EtO, you don't want the plastic absorbing
any of it.

Bleach and alcohol are disinfectants not sterilizers.
Disinfectants REDUCES the number of harmful mircoorganisms.
Sterilizers KILLS all microorganisms.

Not sure it would work but you should look into nylon. Taulman has some FDA approved filament on the way.

EtO and ionising radiation are a little too hazardous for me I think, I am ideally looking for something that would survive the autoclave.

So may have to get a little more creative.

... think about lost cast moulding -- printing with any plastic, moulding with Aluminium or precious metals ...

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Viktor
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Aufruf zum Projekt "Müll-freie Meere" - [reprap.org] -- Deutsche Facebook-Gruppe - [www.facebook.com]

Call for the project "garbage-free seas" - [reprap.org]

You might want to check and see if what you want to make has to be sterile. If it goes inside of the body it has to be sterile and a biocompatible plastic. If it goes on the outside of the body it only has to be disinfected (usually). For instance sutures (stitches) have to be sterile because they go into the body, but a blood pressure cuff only has to be disinfected.

I am looking to experiment with bio reactors for plant tissue culture. Anything that can be used externally -pinch valves, peristaltic pumps etc, disinfection will be Okay, but the ability to sterilise once in a while would be handy. From the responses other parts that will actually come in contact with cultures will need to be cast or cnc'd in appropriate material that can survive a sterilisation processes that I am happy to have around. - Which is all absolutely fine, I just need to know what is or isn't really possible with current main stream 3d printing materials.

edited to add, I am looking at this purely from a hobby perspective of growing plants in test tubes for fun and branching out to small scale reactors rather than as something for a commercial venture or academic study.

Edited 1 time(s). Last edit at 05/23/2013 10:07AM by squeeks.

... the biggest problems with proper sterilization are micron-sized voids in the surface and/or material properties that reduce the resistance against tempeature or aggressive chemistry.

But you can sterilize sensitive parts with radiation - here plastics are even better suited than metal or ceramic parts

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Viktor
--------
Aufruf zum Projekt "Müll-freie Meere" - [reprap.org] -- Deutsche Facebook-Gruppe - [www.facebook.com]

Call for the project "garbage-free seas" - [reprap.org]

- Clearly the best option would be gamma radiation. But don't try this at home!
- Another very classical Method is the autoclave, if you dont have one you can use a pressure cooker for small objects. Should work the same way. Programs like 25 min, 120 °C and 2 bar pressure (atmosphere is already 1 bar) should work properly. Depending on your polymer used you may not be able use this method or you have to adjust it.
- Another possiblity would be chemical methods of desinfection: here ozone and hydrogen peroxide are used. Hydrogen peroxide is quite esay to get, you can try that but be careful with the subtance and it might harm your Polymer as well
- The method I would go for is UV radiation. It is less efficient than gamma radiation but also not as deadly You can get UV-Lamps quite easily and most of the radiation can be blocked by simple glass (strong sunglasses or protective glasses are always recommended when using UV). Put your sample under glass hood and place the UV lamp next to it. Make sure that the UV light reaches all areas. I would leave the lamp for 24 hours. Oh and make sure there is no dust on the lamp or on the sample as dust greatly reduces the efficiency of UV radiation.

- Desinfection. As mentioned before there is still the opportunity of desinfection. Most commenly you mix ethanol or isopropanol with water in a ratio 70:30 alcohol:water. This is supposed to leave 1 out of 10^5 microorganisms alive. Sterilisation (the methods above) however work at least ten times better than that. If desinfection is enough and your sample will withstand ethanol or isoprop then you can use this option.

Edited 1 time(s). Last edit at 08/16/2013 08:00AM by Daniel.