Saline-based electrodes ( Gelfree BCI Electrode Cap Kit)

etcetc Italy
in General Discussion

Dear William,
sorry for my bad English!
I have some questions for you after a lot of time!
I was giving a look to an your new product, the “Gelofree BCI Eclectrode Cap kit”.
I would remember to you that I didn't get a good experience with the Thinkpulse.
You wrote to me (March 2021) about an your electrodes ranking:
“ If you were to rank the electrodes by maximum signal amplitude, I'd probably say:
• gel / paste / wet / saline
• ThinkPulse (which are dry active electrodes)
• then the dry passive electrodes (used in the default Ultracortex or headband you mention.)”

Now I have 2 questions for you:
1) what do you think about the electrodes of this Cap Kit? I got very good performance with the your EEG Electrode Cap Kit with sintered Ag/AgCl electrodes; are the saline-based electrodes of Gelofree BCI Eclectrode Cap kit at the same level?
2) in BCI documentation I read the chapter “Gelfree Electrode Cap Guide”; I found instructions to pair the the Gelfree Electrode Cap with the OpenBCI CytonDaisy 16-channel Biosensing Board. Nothing about the pairing with the Cyton board (8 channels). Is this pairing with Cyton easy and doesn’t it need any other component?

Thank you very much and … sorry for my English!

Ettore

Comments

  • wjcroftwjcroft Mount Shasta, CA

    Ettore, hi.

    Yes, signal amplitude / quality with the saline cap should be identical to what you see with gel or paste. It is the wet nature of the electrode / skin interface that drives the signal quality.

    Even though the Gelfree cap guide mentions Daisy, it is fully compatible with all Cyton and Ganglion configurations.

    Regards, William

  • etcetc Italy

    Thank you very much!
    Do you think that is it enough to order only the kit or do you think that I need some other items to work for some months with the Gelfree BCI Electrode Cap Kit ?

  • wjcroftwjcroft Mount Shasta, CA

    The shop page,

    https://shop.openbci.com/products/gelfree-bci-cap-kit

    Mentions you need one touchproof adapter, for each 8 channels,

    https://shop.openbci.com/products/touch-proof-electrode-cable-adapter

  • etcetc Italy

    Thank you! In the next hours I will order the Gelofree BCI Eclectrode Cap kit + the Header Pin to Touch Proof Electrode Adapter (I would get the 15% off all OpenBCI-branded products... ).
    Another question: in the your documentation I didn't read anything about how to use the saline electrodes, about the solution that I have to use, how to use the solution, how to prepare the solution, how much salt, how much water, etc... . My English is bad, then I post a link where you can see, for another cap with saline electrodes, some operations to do to can use the cap. Are the same suggestions good for the you cap?

    Thank you very much!
    Ettore

  • wjcroftwjcroft Mount Shasta, CA

    Ettore, hi again.

    You are likely referring to the OpenBCI manual,

    https://docs.openbci.com/AddOns/Headwear/GelfreeElectrodeCap/

    However, I'm pretty certain that the cap also comes with a paper manual (or pdf link) from Greentek, which details how the solution is prepared and soaked into the electrodes. You may want to clarify by emailing customer support at contact at openbci.com.

    https://www.greenteksensor.com/products/eeg-caps/gt-cap-gelfree-s3/

    See the Downloads manuals section at end of that page.

    William

  • etcetc Italy
    edited September 2022

    Thank you very much for the link. I gave a loook to the little manual.
    I understood that the use of these electrodes needs a lot of time!
    I read that before the use

    "Wet hydro-links : The hydro-links should be soaked with saline
    solution in the wetting container. It takes at least 2 hours to
    soak the hydro-links (if hydro-links are completely dr y) in
    order to prepare them for proper use. Make sure the
    hydro-links are completely wetted before application."

    After the use:

    " Cleaning and storage
    The hydro-links should be then removed from the hydro-
    link holders and washed in the clean water , at least three
    times, while squeezing out the water each time. Finally,
    he hydro-links should be completely soaked in the solution
    and stored in the wetting container so that they can be
    ready use for a next record ing.
    The hydro-link holders should be rinsed with water, and then
    dried out and placed into a flat box.
    The electrode cap should be washed with clean water and
    dried out completely.
    If necessar y , clean the cap with a dilute householder
    surfactant , while clean the hydro-links and its holders with
    0.2% of a household disinfectant solution for about 10
    minutes. The disinfectant solution can be made with 2ml
    of a household disinfectant into 1 liter of clear water.”

    I am not more so sure that these electrodes need less time than the your traditional wet electrodes... .
    Now I go to read better the manual!
    Thank you.
    Ettore

  • etcetc Italy

    Dear Williams, @wjcroft,
    sorry if I am back on the same argument: the Gelfree BCI Electrode Cap.
    Sorry for these other 2 questions, but before to make the order (I would use the discount for this November!) I would be sure :

    1) the Openbci instructions (https://docs.openbci.com/AddOns/Headwear/GelfreeElectrodeCap/) are written for the use with a Daisy. You told me that also the Cyton was ok. The question is about che connection to the Ref location. For the case Daisy, we have to use a splitter cable from the 2 SRB pins (Cyton + Daisy) + a HPTA Cable + grey cable to the Ref location on the Cap. In the case Cyton, I think that only I have to connect the SRB of the Cyton (no splitter cable) to a HPTA Cable + grey cable to the Ref location on the cap. Am I right?

    2) how many hydro-link sponges come with the kit?

    Thank you!

    Ettore

  • wjcroftwjcroft Mount Shasta, CA
    1. that is correct
    2. I suggest you email (contact at openbci.com) to ask customer support. It's probably the same as what Greentek sells on their website.

    https://www.greenteksensor.com/products/eeg-caps/gt-cap-gelfree-s3/

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