[Eeglablist] acceptable electrode impedance

[장진원]

This is great, thank you so much!

2025년 11월 24일 (월) 오전 5:40, Ivan Gligorijevic <ivang83 at gmail.com>님이 작성:

> Hi Jinwon,
>
> Of course - what I will say is my opinion (EEG hardware/software producer)
> - so you can take it with a grain of salt.
>
> The 10kohm (or 20kohm) mark was a heuristic measure tied to some older EEG
> devices - where basically people "looked" at the signals and backtraced
> what the impedance was. But, essentially, how good the signals are is
> determined by the input impedance of the amplifier - or - in cases of
> active or dry (active) electrodes - the pre-amps on the electrodes
> themselves. That left some of the very good recordings in the very high
> impedance ranges if you know what I mean. So, to conclude, in my opinion it
> is completely acceptable to have higher impedance if your signals are
> looking good.
>
> I don't know what electrodes are using, but if its passive wet (I doubt
> they are based on description but still) - you can always check/cite the
> Ferree/Tucker paper (https://urldefense.com/v3/__https://pubmed.ncbi.nlm.nih.gov/11222977/__;!!Mih3wA!B74BahfJTg839ZPi_nddgIhnRjUjBYyA1vd0nobVttalVHmFkruWt9PfUQbM-cjKM9-CtQkcT7xfi55x25FIg1ZUFQ$ ) for up to
> 40kohm.
>
> There is also the question of common-mode rejection - a separate but also
> connected issue - and, if the amplifier has a very good CMMR then your
> signals will be and look better. For this you can also check the Luck paper
> (https://urldefense.com/v3/__https://pmc.ncbi.nlm.nih.gov/articles/PMC2902592/?utm_source=chatgpt.com__;!!Mih3wA!B74BahfJTg839ZPi_nddgIhnRjUjBYyA1vd0nobVttalVHmFkruWt9PfUQbM-cjKM9-CtQkcT7xfi55x25HDHMEnGg$ 
> ).
>
> If you are using some of the dry systems - you can reach out to the
> manufacturer company - I am sure they have references why this is
> acceptable - because they would be in trouble if they didn't :)
>
> Hope this helps!
>
> All the best,
> Ivan
>
>
>
> On Sun, Nov 23, 2025 at 11:42 PM 장진원 via eeglablist <
> eeglablist at sccn.ucsd.edu> wrote:
>
>> Dear all,
>>
>> The guideline usually recommends to use <10k ohm for electrodes in eeg
>> study. As far as I know, this is important to preclude artifacts and
>> noise. But there are many published studies with >50k ohm.
>>
>> Is it acceptable to use high-impedace electrodes if all signals look good
>> by an eye? Maybe these "good" signals might not mean real good
>> representations of cortical sources.
>>
>> Best,
>> Jinwon
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>