using dry electrodes with Ganglion

VRscienceVRscience
edited February 2017 in Electrodes
Hi everyone,

this is my first post in this forum even if i have been following the brilliant community of OpenBCI for a good while. So, as first, i want to cheer you all and express my appreciation for this cutting-edge and mind blowing project.
That said, i am going to place my very first (and probably silly) questions. 
Would it be possible to use dry electrodes with Ganglion? If yes, what are the pros and the cons.
Have anybody tried to mount Ganglion and electrode on a soft elastic band or cap? Is it feasible?

Thanks in advance!

Cheers,

V.

Comments

  • wjcroftwjcroft Mount Shasta, CA
    VR, hi.

    Yes, FRI has some cool velcro kits available now, check it out. These were developed by Brooks @jbzurn and Karl Zurn @KZurn at FRI. That is Brooks in the photo on the first link. These strap systems are flexible, you can have cross straps to reach the other 10-20 sites.

    https://fri-fl-shop.com/product/headband-kit/

    https://fri-fl-shop.com/product/eeg-headband/

    https://fri-fl-shop.com/product-category/electrode/electrodes/eeg-electrodes/

    There is also a whole thread devoted to dry electrodes in the Electrodes Category. Quite large,

    http://openbci.com/forum/index.php?p=/discussion/138/buying-dry-active-electrodes#latest

    William
  • VRscienceVRscience
    Hi William,

    thanks so much for the quick reply. I was already aware about that thread, but given i am new here, i wanted to be sure that was the right thread to start from.

    So my starting system should have: 

    3) Lead wires for disposable/reusable dry electrode

    Rather than the headband, could it be possible to use this kind of Cap?

    Thanks,

    V.
  • wjcroftwjcroft Mount Shasta, CA
    V, yes, that's Brooks @jbzurn in the photo. And Karl @KZurn at the left photo at the bottom of the page.
  • celticharpcelticharp Athens, Greece
    Hi,
    I'm also interested in dry electrodes for Ganglion.
    My cart so far at FRI is:

    Do I need anything else? Is this configuration usable by Ganglion?
    Thank you.
  • wjcroftwjcroft Mount Shasta, CA
    I've heard that using the gel with the FRI electrodes may result in faster thinning of the plating coating. That is why they are called disposable. For dry use, you do not need the gel.

    For forehead or bare scalp areas, you want the cone shaped electrodes. The combs are too pointy for bare skin.

    You need the OpenBCI adapter that converts touchproofs to header pin connectors.
  • celticharpcelticharp Athens, Greece
    edited February 2017
    Thank you for your answer!

    By cone shaped electrodes you mean this? It is labeled as wet electrode though. 
  • wjcroftwjcroft Mount Shasta, CA
    Yes. The cones and combs are what Ultracortex uses. They are used dry by all headset users. These electrodes were originally designed by the manufacturer for insertion of gel through the back hole. At the time they had no idea that OpenBCI would pick up the same parts and use in their dry headset. FRI is not the original manufacturer, but a distributor / retailer for the OEM.

  • celticharpcelticharp Athens, Greece
    Wait, so this cone shaped electrodes can be used as dry, as long as you don't apply paste into it?

    So for my setup I will need comb for the hair areas and cones for the bare skin areas without applying any gel, right?
  • wjcroftwjcroft Mount Shasta, CA
    Correct. As I said, this is exactly what is used in the Ultracortex.

    FRI has some kits with a mix of cone and combs.
  • celticharpcelticharp Athens, Greece
    Thank you so much! You're so helpful!

    I have read at the manual at the FRI's site that these electrodes can be used at least 20 times. Do they have a limited lifespan, taking into account that I will not be using the gel ? (I'm asking you in order to increase/decrease the quantity of the electrodes that I will order).

    "You need the OpenBCI adapter that converts touchproofs to header pin connectors." Ouch! I'm afraid I cannot afford two shippings from the US altogether! Does this adapter can be found elsewhere except OpenBCI's eshop? (in Europe)
    Thank you again for your quick replies.
  • wjcroftwjcroft Mount Shasta, CA
    I think the 20 figure might have been with gel or paste or saline. Dry usage should be more, probably double or triple that. Just check your impedances. If less than about 50Kohms you should be fine, even if some of the AgCl wears down. There is Ag under that.

    To plug the FRIs into header pins, just cut off the touchproofs on the FRI cables and splice with a header pin female connector cable (cut in half), such as,


    If you cut the touchproof off say 3 inches from the end, then if you ever needed that type of connector in the future, you could splice it back on.
  • celticharpcelticharp Athens, Greece
    Great! Thank you for your time. Have a nice day!
  • celticharpcelticharp Athens, Greece
    One last question: What will have a better connection at the dry electrodes, the cap or the headband? I guess the cap will apply a general pressure at the head while the headband will be more adjustable. Am I right? Anything else to consider between these two?
  • wjcroftwjcroft Mount Shasta, CA
    Yes, the velcro is adjustable pressure. I havent used Brooks' cap, so can't say what the pressure is. Why not ask her? Click on @jbzurn, then use the Message button. Or Karl @KZurn might comment here also.

    It would be fun to get your review of the cap or bands once you have them.
  • celticharpcelticharp Athens, Greece
    They just answered me on email. The cap is not available right now so I might choose the headband. Simple vs EEG headband is now my dilemma! 
  • celticharpcelticharp Athens, Greece
    @wjcroft
    Regarding :

    "To plug the FRIs into header pins, just cut off the touchproofs on the FRI cables and splice with a header pin female connector cable (cut in half), such as,

    https://www.adafruit.com/product/266

    If you cut the touchproof off say 3 inches from the end, then if you ever needed that type of connector in the future, you could splice it back on."
    Is this process going to affect the signal quality? Because the female's cable that I am going to solder at the electrode cable in order to connect it with BCI won't be the original one.
    Thank you.
  • wjcroftwjcroft Mount Shasta, CA
    No, it does not affect signal quality. These exact same connectors are on the gold cup electrodes.

    The 'preferred' way to go is with the adapter sold by OpenBCI. Then you can switch back and forth. In your case with extra import considerations and order time, etc. Just switching the connectors is easy.

    William
  • celticharpcelticharp Athens, Greece
    It's ok, I will proceed by cutting the lead cable and solder them to female jumper wires. I never intend to go back to touchproof. Thank you William!
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