[3dem] Cryo Plunger for cryo EM

[Brink Jaap]

Hi,

There ought to be a set of workshop drawings floating around on the internet for a simple plunger that Tim Baker was using when at Purdue (not sure what he uses now). Anyways, this plunger has al the features of a cheap but very effective plunger you’d need. Comes with footpads release …. If you can’t find them, drop me a note off-line.

Jaap



> On Jan 28, 2015, at 2:58 PM, benoit.zuber at ana.unibe.ch wrote:
> 
> Hi Andrea,
> 
> Depending on what you want to do, you could also have your mechanical workshop build one plunger for less than hundred euros. It needs an arm that you can attach tweezers on. The arm needs to be heavy so that it accelerates well during free fall. It needs to be long enough to reach a sufficient speed when the grid will touch ethane. And it needs a release mechanism triggered either by hand or preferably by a foot pedal if you want to hold the blotting paper with both hands. To prevent the cryogen to get frozen, you can use a mixture of Ethane and propane, have small resistance in the ethane container, or have the container in contact but not fully immersed in liquid nitrogen. That way ethane is not cold enough to freeze but it is cold enough to vitrify water. You can check with a thermometer that the temperature is correct before starting to plunge. We use such a plunger most of the time and are absolutely delighted. Never a software bug or any blocked pad, or expensive maintenance contract/Cost. whatever other problem. It takes a bit of practice at the beginning to get the feeling for the blotting in order to get the right ice thickness but after a few sessions you will have it and just like riding a bike, you will not forget it. Glow discharging the grid in amyl amine atmosphere is said to help against evaporation and therefore get reproducible ice thickness (I used to do that but we don't anymore). Some people will tell you that controlling humidity is absolutely critical, that the grids will dry otherwise. I do not exclude that there are cases where humidity control matters but quite often it does not. If this is a concern you can anyway get a humidifier from the local supermarket and put the plunger in a rather closed and chilled hood (taking care though not to ignite ethane)!
> 
> Best 
> Benoît 
> 
> 
> 
> Le 28 janv. 2015 à 18:22, Andreas <andreas.schmidt at uni-ulm.de> a écrit :
> 
> Dear all,
> 
> I am a PhD student at the University of Ulm, Germany and our Institute wants to buy another cryo plunger. We already bought a Gatan CP3 and now I was asked to look for other commercial available cryo plungers. So far I also found the Vitrobot by FEI, the EMS-002 Rapid Immersion Freezer by EMS and the Leica EM GP by Leica. Are there any other companies selling cryo plungers and would you recommend them? Or is there anyone who would like sell their old device?
> 
> 
> Best regards,
> Andreas
> 
> -- 
> Andreas Schmidt
> Biochemist
> Institute for Pharmaceutical Biotechnology
> Ulm University
> Helmholtzstrasse 8/1
> 89081 Ulm
> Germany
> 
> Tel: +49 (0)731 503 2767
> Email: andreas.schmidt at uni-ulm.de
> 
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