MindAffect headband setup discussion

This discussion was created from comments split from: signal amplitude: dry Ultracortex with P300 or cVEP [resolved].

Comments

  • jetjet U.S
    edited August 2021

    Hello again,
    I have contacted the MindAffect info contact, and they stated that https://shapeways.com/ is able to 3D print the headband, and that TMSi electrodes are available (although the servers are offline at the moment).

    I tried incorporating a photoresistor with my board following this guide:

    https://mindaffect-bci.readthedocs.io/en/latest/build_your_own_optical_sensor.html

    When running the OpenBCI GUI and alternating between dark and light areas shone onto the photoresistor, multiple channels would cross talk, even though the photoresistor was only connected to one channel. It was seldom that only one channel would show a response. However, it is apparent that there is an effect as shown with the signal responses, but it is unclear whether the cross talk is due to hardware or software issues.

    I have checked the firmware of the Cyton board, and it is currently up to date at v3.1.2.

  • wjcroftwjcroft Mount Shasta, CA

    Channel crosstalk may just be a side affect of their circuit wiring and induced capacitive / inductive coupling. The important aspect is that their tests check the timing accuracy of your display hardware. Once that is determined to pass their requirements, their wet headband will then give the best occipital signal strength.

  • jetjet U.S
    edited September 2021

    Hello again,
    I have ordered TMSi electrodes and 3D printed the headband that MindAffect uses. The issue now is that the electrode wires cannot directly connect to the Cyton board, so there must be an adapter needed. I saw on the OpenBCI shop that you guys had this:
    https://shop.openbci.com/collections/frontpage/products/touch-proof-electrode-cable-adapter?variant=31007211715
    However, this is the male variant of the pin that should connect to the TMSi electrode wire.
    Here are what the TMSi electrode wire ends look like:


    Is the OpenBCI header pin suitable as a connector or are there any other available options that are not male and instead female? And, if so, what exactly are they?

  • wjcroftwjcroft Mount Shasta, CA

    Hi Jet,

    Does this MindAffect page show your same TMSi electrode?

    https://mindaffect-bci.readthedocs.io/en/latest/fitting_guide.html

    The plug end in your image above (white plug) looks odd for an electrode. Here are what normal EEG 'touchproof' electrodes look like, the topmost plug in this image:

    The wire from a normal EEG electrode has a plug that has a smaller diameter 'male' outer shell, but inside the shell is a female connector. Then these EEG electrodes plug into a wider shell that appears 'female' on the outside, but actually has a male pin on the inside. That is why the adapter that is listed in the shop, is designed to mate with normal EEG electrode wires.

    Now YOUR photo you show, appears to have a male pin inside, that means it is not a normal EEG electrode, but is designed for an EEG electrode to plug into. Completely odd if this is your electrode wire. I wish the MindAffect page on their electrode setup was more specific about what to order. Are you sure you got what they recommend?

    The easiest solution, assuming you just want to get going, is to CUT the TMSi wire off, say a few inches from the plug end. That way you can reuse the connector if you ever need it for some weird reason.

    Then purchase a pack of jumper cables, for example,

    https://www.adafruit.com/product/826

    These have male on one side and female on the other. Cut one of these in half, and splice the female connector onto your TMSi cable. I assume you know how to cut, strip, and twist wires together to splice. Then use some tape to wrap the joint. Or if you are fancy, you can use shrink wrap tubing and a heat source to seal the joint. (Electronic techs have such tubing.)

    Your TMSi wire now will plug into the header pins on the OpenBCI board.

    Regards, William

  • wjcroftwjcroft Mount Shasta, CA

    Please post the ordering information / links for the band from Shapeways and the MindAffect recommended electrodes. Can you also ask them to post on their page, https://mindaffect-bci.readthedocs.io/en/latest/printing_guide.html . Perhaps adding a new section for parts ordering.

  • Thank you for your previous response. The site for the Shapeways 3D printed files are here: https://github.com/mindaffect/Headset; the attachment file was printed with TPU, and the main file was printed with https://shapeways.com/materials/pa11. The MindAffect electrodes are the TMSi electrodes if that answers your response:
    I recently found images of TMSi electrode wire adapters connected to the Ganglion board. I have a Cyton board. Although I have tried cutting the electrode wires and twisted them with a cut jumper wire, this offers a much cleaner solution.


    Do you know where I can find this kind of adapter?

    In addition, it seems as though the TMSi electrode does not fit into the 3D printed headband. As shown in the images above, there is an orange piece that is inserted into the holes of the headband, and the electrode follows it. However, this part was not provided in the Github link previously mentioned.

    Here you can see that the issue with the headband is either scaling or the missing piece that is supposed to be inserted onto the other side of the band with the dip.
    Do you know where I can find this part?

    Thanks.

  • wjcroftwjcroft Mount Shasta, CA

    Jet, hi.

    I'm sorry you are having difficulty assembling the MindAffect headband. My suggestion is to use the same contact you had previously to determine the Shapeways info and TMSi part number. And ask where are the orange foam inserts. As well as the adapter they use. The solution of splicing the connector actually is pretty easy to do.

    William

    PS I still do not have the TMSi webpage or part number for the electrode. This you must have obtained from MindAffect.

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