Buying ear clips

jonathanjfshawjonathanjfshaw Stroud, United Kingdom

I'd like to use a linked ear reference as that seems like the best choice with a low channel system like Ganglion. I'm having buying this because:
(1) I'm not sure what's easily compatabible with the Ganglion pins or easily convertible, my electronics terminology is poor
(2) Similiarly I'm not sure if there's an easy way of connecting 2 independent clips, what the terminology is
(3) The kit I can find is weirdly expensive like fifty dollars for a single ear clip
(4) I'm in the UK
Ear clips are included in the open bci eeg headband kit, but don't see to be sold seperately.
Can anyone give guidance on what exactly I need to buy to do linked ears with the Ganglion, and where to look for it?

Comments

  • wjcroftwjcroft Mount Shasta, CA

    Jonathan, hi.

    The FRI ear clip is here, these are silver chloride (plastic base, then silver plated then chlorided.)

    https://www.fri-fl-shop.com/product/td-430-silver-disc-electrode-ear-clip/

    What electrodes do you currently have? You should in general not mix types of electrode metals (such as gold vs silver). The FRI electrode shown uses the typical DIN connector. For OpenBCI pins, you want a female header connector. You could cut one of these from a jumper kit and splice in place.

    https://www.adafruit.com/product/1954

    FRI also has gold cup ear lobe clips,

    https://www.fri-fl-shop.com/product-category/ear-clips/

    Regards, William

  • wjcroftwjcroft Mount Shasta, CA

    As far as linked ears, you can make a 'Y-cable' by splicing from the jumper kit, TWO male ends, to ONE female end. Plug the female into the Ganglion, and the males into the ear clip leads.

  • jonathanjfshawjonathanjfshaw Stroud, United Kingdom

    Thanks so much for your answer William. Knowing now that I can create a linked ears with nothing more than scissors and sellotape makes the planning much easier!

    Likewise knowing that it's fine to do the same to convert touchproof to header is really helpful, though I see that helpfully there is also: https://shop.openbci.com/products/touch-proof-electrode-cable-adapter

    At the moment I'm hoping to use saline, inspired by your https://sites.google.com/site/biofeedbackpages/velcro-sensors

    I've fiddled around with carefully gluing sponge to standard adhesive electrodes (ensuring that the sponge is in contact with the actual ceramic-like electrode disc) . I have standard snaps (I assume stainless steel) that then snap on to these sponge electrodes. Do you reckon this should work?

    If it does work, then maybe I'm OK to use any kind of metal for the ear electrodes, as I won't have the gold/silver/agcl mixing problems?

    If that is viable, I'll probably get tin ear electrodes as they are cheap and retailed in the UK http://www.unimed-electrodes.co.uk/E5-Ear-Electrodes-6mm--cup-TP-Connector-(Pair)/201 and might be adaptable to gold cup anyway.

  • wjcroftwjcroft Mount Shasta, CA

    EMG/ECG adhesive disk electrodes are pre-gelled, and contain a Ag-AgCl (silver-silver chloride) disk at the center, and a male snap connector on the outside. If you looked at the velcro-saline article, you can see that everything comes apart for periodic cleaning. I don't know what kind of 'sponge' material you are using, but I found the synthetic 'chamois' cloth worked best in the article. It should be both thin / compressible and very absorbent. I recommend using the Ag-AgCl ear clips, so you are using same material throughout. But the tin ear clips may work. Another source of Ag-AgCl ear clips is listed in the article.

    The general rule of not mixing electrode metal types, may not apply when one of the 'metals' is chloride plated silver. This is because no actual metal is in contact with the skin. The silver layer is covered in chloride coating. As long as this dark / grey coating is intact, there is no metal exposed.

    But mixing the normal metals: tin, gold, silver, will result in galvanic 'battery' effects, wrecking your signal quality.

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