Commercial saline sensors

Here is a list of links to commercial saline based EEG sensor systems.

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EUROPEAN NET AND POST

This is an example of the European system mentioned on the main page.

http://www.pamel.hr/index.php/en/proizvodi/eeg-kape-elektrode-pribor

This sensor design originally came from Europe, but it is also in wide use in Asia.  You purchase the set of sensors along with a 'cap' system consisting of left / right 'endplates' with holes, and elastic straps that stretch between plates across the 10-20 lines. Usually a chin strap is also used to hold it all down.

The sensors have a felt pad that stretches across the top of a flat round screw post (kind of mushroom shaped), held on by an o-ring. You moisten the pad with saline solution, then tuck under the corresponding strap at the desired 10-20 position. Lever-action holds it down in place on the skin.

Some practitioners still use paste or gel with these pads, but I think saline solution is more widely used.

Just recently STENS Corp. here in the U.S. is now carrying this same type of headset, they call it Minicap.

http://stens-biofeedback.com/collections/parts-and-supplies/products/minicap-for-the-nexus-4-10-32

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OPEN FOCUS

Another historical system from the U.S. was that developed by Les Fehmi in the 1980's for his 5 channel Open Focus synchrony training.  This has 5 fixed position sensors (Fpz Cz Oz T3 T4) on an elastic band with velcro closures.

Elastic bands and conventional velcro is used (not One-Wrap), so the positions / pockets are fixed to the five 10-20 sites mentioned.

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FLEXTRODES

http://bio-medical.com/products/flextrode-package.html
http://www.futurehealth.org/bm_flextrodes.htm

FLEXTRODES consist of a hollow, screw-like plastic retainer containing a felt wrapper that encloses a standard gold cup electrode.  They are used with a retaining ring that can be inserted in a headband, hat, or other holder.

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A similar system with a locator cap containing holes for all 10-20 positions.

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GEODESIC SENSOR NET

http://www.egi.com/clinical-division/geodesic-sensor-nets

On the high end, Geodesic Sensor nets also use saline silver chloride sensors.  This mesh is dipped into a bucket of saline solution.  Then the net is pulled over the head and sensors are individually wiggled to contact down on the scalp.  However only comes in large channel counts, 32, 64, 128, 256.

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EMOTIV EPOC

The Emotiv EPOC is a saline system.  I'm not sure what metal is inside their connectors, silver or gold?  They have female sockets on the headset that accept little felt cylindrical pads that slip into the sockets.  Pads are then moistened with saline before each use.  They do sell kits with more pads, so I understand these wear out over time.  I've also heard their users on forums complaining that the felt pads fall out or can be intermittent.  Maybe they have solved this.

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NEUROBAND

Diane Stoller developed a velcro based system by hand sewing the straps out of separate hook and loop material. However this substantially drives up the cost, in terms of additional cost per strap. The Velcro One-Wrap tape we are using essentially does the same function as these straps, but with no additional cost per strap. (Once you have purchased the $10 twelve foot roll of 3/4" strap material.)

http://www.drdiane.com/product-category/neuroband/

For the sensor pockets, Neuroband uses actual animal skin chamois material, instead of the better performing (more absorbent) cloth chamois we are using.  The cloth also I feel can be more easily cleaned, and does not have the micro pocket cellular structure of dried out skin to deal with.

She does sell a silver chloride type of button snap, however the button is not replaceable (it is sewn to the chamois), thus has high replacement cost of $10 each.

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