Automated valve for testing module

Question

I work frequently with materials sensitive to oxygen and moisture, within a glove box. However, there are frequently times I want to move these samples from the glove box to a scanning electron microscope (SEM) or other device without exposing them to air. I can easily use some small module (eg tupperware) which can be sealed manually in the glove box to allow me to safety transfer my samples to another glove box. But, if I want to see it in a SEM or another device, I must have another way to transfer it without exposure. These samples can be very very small, 1 inch in size or less.

I could easily build a small box or module for transferring my samples, and seal that box by hand in the glove box. However, I need a mechanism I can use to unseal the module once it has been placed inside of another device, where it is inaccessible by hand. If I could find a small valve that could be opened automatically, that would be suitable for example.

Can anyone suggest such a mechanism for breaking a sealed environment automatically?

Answer 1

Interesting problem. The box is under vacuum, so thankfully that works in your favour when you're transporting it in atmosphere as the air will push down on any seals, helping to keep it closed. This means you don't need to go overboard with any gaskets/compounds/o-rings etc.

When the box is safely back inside a vacuum (the SEM) The pressure on any seals due to air will be negated so whatever is driving the lid open/closed will not have to be large.

I can't think of any off the shelf ideas so here's one potential way. My solidwork skills leave A LOT to be desired so don't judge me too harshly! I've just put in what i thought was needed to get the point across. There's many different mechanisms to do this same thing, just converting rotational to linear action (scotch yoke/ leadscrew etc).

To make the box actually choose when to open/close is another issue. You can implement a timer (with an arduino perhaps) to give you enough time to transport it and let the SEM pump down, or even add an external pressure sensor to the box to only open when the external pressure of the box is acceptable.

One major thing to be wary of with any home-made system though is potential contamination of the vacuum system. If any capacitors or even the battery outgas (according to EEVBLOGs forum lithium battery's can survive due to the lack of liquid in the cell) then you'll be at fault.

If your SEM has external handles to manipulate the object under scan this problem gets much easier!