Conductance gel

[partylab]

Hi

I'm looking into trying some different types of conductance gel. Currently our lab uses ECI Electro-Gel (thats the electro cap product).

I'm curious to know if other conductance gels may have higher saline levels that would make it easier to bring impedances down? Our current work with children requires us to have impedances below 5 kohms. Usually this requires manipulating the gel/electrode with a stick....which we would like to stop doing.

Any suggestions?

pl

[Coen]

With BioSemi active electrodes, it is not necessary to reduce the impedances by scrubbing. The signal quality is optimal without any skin preparation.

Best regards, Coen (BioSemi)

[smcphers]

We use Signa Gel which has a 0.5% saline base which works quite well.

[terracop]

There are several gels which will do the job. Signa is fine. But most interesting is to know how do you measure impedances and why?

[Alexandre]

[quote]most interesting is to know how do you measure impedances and why?[/quote]

Indeed I understood that because of active electrodes, no scrubbing is necessary, but still, how can i control that the contact between the electrodes and the skin is good enough (especially in the case of using paste for electrodes outside cap (i.e. ARB recording) ?

Thanks in advance for your reply

[Coen]

The electrode offset gives a good indication of the contact quality. The offset should be stable, and within the +50 mV and -50 mV range.

The ABR software offers an additinal (and best possible) check of the electrode contact quality: you can actually measure the electrode noise level with the online averager (gray traces in the graphs).

Best regards, Coen (BioSemi)

[Alexandre]

Thanks, I will try this out !
Best