<p>The number of channels are not the issue at all, its the electrodes that are at fault for your wrong readings. Dry electrodes/ water based electrodes have a much higher impedance when placed on your head. They record relatively good signals but require the user to be absolutely still, any slight movements and muscle/facial movements - even blinks can cause high frequency artifacts and distort your signal horrendously, which might be the reason that you are only viewing Eye blinks in your EEG. Gel based electrodes are the best but extremely irritating to use, the sticky feeling on your head after the experiment is done, is totally the worst.</p>

CC BY-SA 4.0
2019-07-10T01:01:54.837Z
2019-07-10T01:01:54.837Z
roaibrain
<p>Yes and sort of. </p>

<p>Dry electrodes are known for lesser signal quality in comparison to "wet" electrodes. Adding some paste/gel to dry electrodes does help. My professor just got an Emotive Insight and found that this helped quite a bit. </p>

<p>More electrodes does not automatically improve the channel to channel quality. However, more electrodes will allow you to measure activity on different locations more precisely. This may improve your ability to recognize different patterns and, therefore, more processes than blinks and movements. More channels will also improve the quality of Independent Component Analyses (ICA), a tool for recognizing and correcting artifacts. </p>

<p>I cannot tell you how much it will improve though. You can have a look at thesignal-to-noise ratio, but I don't know if you can actually calculate values, or that it only provides a theoretical idea/trend in improvement. </p>

CC BY-SA 3.0
2016-04-16T20:14:19.913Z
When you say "dry" and "wet", you mean "active without gel" and "passive with gel" ?
lytex
CC BY-SA 3.0
2016-04-16T20:21:36.277Z
Yes indeed. I had to google the difference between active and passive though. I am also just a beginner namely.
Robin Kramer-ten Have
CC BY-SA 3.0
2016-04-16T11:02:21.017Z
2016-04-16T11:02:21.017Z
Robin Kramer-ten Have
<p>I'm a EEG hobbyist using <a href="https://www.olimex.com/Products/EEG/" rel="noreferrer" title="Olimex EEG SMT">Olimex EEG SMT</a>, and I'm using 4 dry, active electrodes to record EEG signals (the Olimex uses bipolar montage, so I actually have 2 channels). However, I cannot measure any waves apart from eye movement and hand/leg movement. I'm thinking of spending more money to improve my EEG setup but I don't know exactly why I'm getting this poor quality recordings.</p>

<p>Why I am not getting better results? Do I need conductive paste or do I need more channels?
Would conductive paste improve my results? How much?
Would more channels improve the signal together with signal processing?</p>

CC BY-SA 4.0
2021-12-09T01:34:59.420Z
Had the same results as you with the Olimex EEG SMT, ended up switching to the [Unicorn Brain Interface](https://www.unicorn-bi.com/) (from g.tec), which also has dry electrodes but offers markedly better performance.
David Cian
<eeg>
EEG Signal quality
lytex
# EEG Signal quality

(Asked by: username_0 on 2016-04-14)

I'm a EEG hobbyist using [Olimex EEG SMT](https://www.olimex.com/Products/EEG/ "Olimex EEG SMT"), and I'm using 4 dry, active electrodes to record EEG signals (the Olimex uses bipolar montage, so I actually have 2 channels). However, I cannot measure any waves apart from eye movement and hand/leg movement. I'm thinking of spending more money to improve my EEG setup but I don't know exactly why I'm getting this poor quality recordings.

Why I am not getting better results? Do I need conductive paste or do I need more channels?
Would conductive paste improve my results? How much?
Would more channels improve the signal together with signal processing?

**Tags:** eeg

> **Comments:**
> **username_1**: Had the same results as you with the Olimex EEG SMT, ended up switching to the [Unicorn Brain Interface](https://www.unicorn-bi.com/) (from g.tec), which also has dry electrodes but offers markedly better performance.  

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## 2 answers

### Answer by username_3 on 2016-04-16. Score: 2 | Accepted answer

Yes and sort of.

Dry electrodes are known for lesser signal quality in comparison to "wet" electrodes. Adding some paste/gel to dry electrodes does help. My professor just got an Emotive Insight and found that this helped quite a bit.

More electrodes does not automatically improve the channel to channel quality. However, more electrodes will allow you to measure activity on different locations more precisely. This may improve your ability to recognize different patterns and, therefore, more processes than blinks and movements. More channels will also improve the quality of Independent Component Analyses (ICA), a tool for recognizing and correcting artifacts.

I cannot tell you how much it will improve though. You can have a look at thesignal-to-noise ratio, but I don't know if you can actually calculate values, or that it only provides a theoretical idea/trend in improvement.

> **Comments:**
> **username_0**: When you say "dry" and "wet", you mean "active without gel" and "passive with gel" ?  
> **username_3**: Yes indeed. I had to google the difference between active and passive though. I am also just a beginner namely.  

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### Answer by username_2 on 2019-07-10. Score: 0

The number of channels are not the issue at all, its the electrodes that are at fault for your wrong readings. Dry electrodes/ water based electrodes have a much higher impedance when placed on your head. They record relatively good signals but require the user to be absolutely still, any slight movements and muscle/facial movements - even blinks can cause high frequency artifacts and distort your signal horrendously, which might be the reason that you are only viewing Eye blinks in your EEG. Gel based electrodes are the best but extremely irritating to use, the sticky feeling on your head after the experiment is done, is totally the worst.


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