electrode choice and gel choice

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Yueqing Li
Posts: 51
Joined: 08 May 2007, 16:41

electrode choice and gel choice

Post by Yueqing Li » 09 May 2007, 11:49

hi, Dr. Schalk:

1. We have two kinds of electrode: Au and gold (Cupelektrode Gold 10mm). We use Au to get brian signal, and gold for reference and ground. Is that right?

2. It seems that we have two kinds of gel:signal gel (electrode gel) and Elefix paste for EEG. Do they both work?

Thank you.

gschalk
Posts: 615
Joined: 28 Jan 2003, 12:37

Electrodes ...

Post by gschalk » 10 May 2007, 20:34

Yueqing,

1) You should always use the same electrode type for all placed electrodes. From what you say, Au and gold, it seems like they are both gold. Au is the chemical element name of gold.

2) You first need to prepare the scalp using abrasive paste. I think the Elefix is an abrasive paste. Then you use electrode gel in each electrode.

I strongly suggest that you seek advice from somebody with EEG recording experience. Otherwise, the chance to set everything up correctly will be quite modest.

Gerv

W.A.S.
Posts: 1
Joined: 11 May 2007, 13:10

Reply to EEG Electrodes and Gel/Paste questions

Post by W.A.S. » 11 May 2007, 13:32

You should be using the same electrodes for scalp recording as well as ground and reference applications.I primarily use tin(Sn) electrodes which are very easy to maintain as well as having a long usable lifespan.
I've seen Au or gold electrodes develop significant corrosion after relatively short periods of use which could lead to poor recordings and ultimately a b.c.i that won't work all that well.Keeping your electrodes clean will also help with recording quality.Abrasion of the electrode sites is an option especially if your trying to minimize impedence,but you may wind up breaking or irritating the skin where the elctrode is to be placed,which can lead to infection over time.

As far as use of gel/paste goes,electro-gel works well for scalp recording.
It is conductive and washes out easily after use.I have used this product for over 10 years in B.C.I. applications without any ill effects to subjects scalp/skin.Paste is traditionally used for EMG recordings,but can be used
for most types of electrophysiological surface recordings.Problem is it is more difficult to clean out of the hair,and may cause some irritation to the skin(abrasive paste).

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