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Holder/stand for probe

  1. Jul 28, 2009 #1
    I am currently having a bit of trouble on my design. If you have any ideas please let me know.

    I have a crystal disc that is held horizontal above the chamber. It is a vacuum chamber, that is less than a foot in length.

    [crystal] <--(force){probes}

    I'm trying to have two probes contact the surface of the disc without using an epoxy. My current idea is to use spring loaded test probes that make proper contact. The problem is I don't have enough force to press down on the spring loaded probes. The crystal produces charge so I can not use a metal holder. Are there any companies that sell telfon holders? Does anyone know of a stand that is insulated and commonly used for test probes? Perhaps I should try a different route and use electrodes? Would electrodes make proper contact in a vacuum?
  2. jcsd
  3. Jul 29, 2009 #2


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    Welcome to PhysicsForums, azoeth!

    Can you post a picture? Also, if you have access to a good machine shop, this is the sort of thing that they'd be able to make for you, and help you design.

    I'd suggest instead of using a spring-loaded setup, that you use a teflon clamp (think C-clamp, but made of teflon--you can probably get this from McMaster-Carr, or have your machine shop manufacture something pretty easily). The (softish) teflon should be able to deform and hold your sample in place.

    If you need electrical contact, you can use some aluminum (or other vacuum-suitable) foil and cover the faces of your clamp and attach these to your probes. Or you can use some SEM carbon tape or paint (but they'll obviously be higher resistance).
  4. Jul 29, 2009 #3
    Thanks Matlabdude for the advice,

    I think the point I was trying to illustrate was the sample is already held into place. I need to apply pressure to the probes to make contact with the sample. Something like a stand made of telfon.

    I do not have access to a machine shop, however I will look into the c-clamp idea. It appears that McMaster only sells metal c-clamps. Attaching probes to the back of the foil with the clamp might work.
  5. Jul 31, 2009 #4


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    Maybe you could make some simple clamps out of ABS tubing or such-like, and plastic springs are not unheard of. I'm still not exactly sure what you need to do, but maybe this can help. If you can post a diagram (even a rough one), it'll make it a lot easier to diagnose. I'll be glad to help you design something that you can make yourself if such is compatible with your needs.
  6. Jul 31, 2009 #5


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    You can make cheap clamps by cutting pieces of PVC drain-pipe and sawing out a longitudinal section that is just a bit smaller than the gap you need the clamp to span. Cheap, and easy to do with no design and set-up costs at a machine shop. Tools needed: saw that can cut PVC (hacksaw will do fine) Sharpie to mark the pipe, and a cold beer to celebrate. If you have a vise, that's a plus.
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