[3dem] Cryo Plunger for cryo EM

[John Crum]

Hi Andreas and list members,

You have listed all four currently available plunge freezers.

Most manual plunge freezers are lab built (by university machine shops).  I
am designing and building a manual plunge freezer, based on the Purdue
design (I have a copy of the blueprints).  The target price is in the $5K
range.  It is still a few months out...

I've also designed an accessory for the manual plunge freezer- an insert
for the dewar which holds an ethane cup and has a worktable with holders
for square or round cryo grid boxes.  This is currently available directly
from Shapeways (a online 3-D printer job shop) at http://shpws.me/CUvT.
Price is discounted now for early adopters (beta testers).

Cheers,

John Crum
Electron Microscopist
JC Designs/California

On Wed, Jan 28, 2015 at 12:58 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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