Electrodes — OpenBCI Forum

Disinfecting Metal Snap Electrodes Possible?

Bruce276 — Fri, 10 Jul 2026 19:46:02 +0000

Hello, a few years ago I had asked if cleaning the AgCl snap electrodes (https://shop.openbci.com/products/eeg-snap-electrodes) would be necessary and to my understanding, that it is rarely needed unless there is visible residue. However, I am now in the process of planning an experiment with volunteer subjects and I would like to primarily use these metal electrodes in my experiment. Usually it's a good idea to disinfect EEG caps and electrodes in between subjects, thus what would be a good procedure to disinfect these electrodes without corroding them? If there is such a standard procedure where might I find the documentation for it? I would imagine using a low concentration of disinfectant would be the way to go, but I want to make sure if I can use disinfectant and what kind/brand would be recommended.

An additional question if anyone could answer it, where might I find a good site to buy EEG caps at 3 different sizes (large, medium, small) that would be compatible with these electrodes. Something like this cap I found on amazon:

https://www.amazon.com/Meditation-Tracking-Relaxation-Elasticity-Comfortable/dp/B0GT3SR576/

openbci EEG electrodes MAEK IV

ty704366451 — Tue, 30 Jun 2026 01:30:58 +0000

Are there any geeks discussing technology? If so, I can provide free tutorials
I can provide the source code I wrote

All electrodes railed (Daisy device)

lweberairbus — Mon, 27 Apr 2026 07:43:13 +0000

In our company we conduct biosensing experiments, mainly with regards to workload estimation.
We use the EEG Daisy device and now a problem occured with it:
All signals are railed, although the impedance test is confirming low resistivity.
The device was applied to further experiments and studies before and worked error-free until now. I haven't changed any settings on the board and cannot retrace why all signals are suddenly not getting any voltage. Has anyone experienced similiar problems or has an idea what could have caused this misfunction? I would be happy about all hints, which could help finding a solution.

EEG Headband Kit Compatibility with Third-Party Boards

melon — Wed, 13 May 2026 08:22:19 +0000

Hi everyone, I'm a final-year engineering student working on an SSVEP-based BCI senior project and I'm considering combining the OpenBCI EEG Headband Kit with the PiEEG IronBCI board instead of an OpenBCI board.
Since the headband kit's electrode cables use 0.1" (2.54mm) female header connectors, would they plug directly into the IronBCI's electrode inputs without any adapters? Or is there something specific about the OpenBCI headband kit that makes it only work with OpenBCI boards?
Any experience with this combination would be really appreciated!

EEG Snap Electrodes Information

carlos_lorenzo — Sat, 18 Apr 2026 08:47:23 +0000

Hi, I'm designing my own EEG active electrodes and some questions regarding the pasive electrodes sold:

I'm guessing they're dry electrodes but as its stated nowhere on the product page would like to confirm it.
Is there anywhere I could get the exact dimensions of the electrodes as I need to design the hardware around them?
I was thinking about connecting them to the pcb via pogo pins as all of the snap cables ive found have the cable horizontally. Is there any other "recommened" way of connecting them with a PCB that will sit right above them?

Thanks

Lower SNR after first day of use

smanne — Sun, 15 Mar 2026 09:15:38 +0000

Hi,
I'm using the electrode gel cap with the Cyton Board and while I got good SNR on the first day of use, it has dropped significantly on subsequent days and I can't seem to recover it. After the first day of use I brushed off all remaining gel but didn't soak in water. I soaked in non-distilled water AND brushed on all subsequent days. How likely is it that the problem is because of dried gel / mineral build up on electrodes (even though I've only been using them for a couple days)? Or is it more likely the problem is with low-signal REF/BIAS pins? Impedance seems to be fine according to checks in the GUI.

In the GUI Cyton Signal widget under "Live" the signal ranges from 0.2%-5% across channels. When I take the electrode cap off my head and keep streaming data, the signal shoots up to between 10-100%.

I also see much stronger and sensitive signal when I connect SRB2 to AGND on Cyton Board instead of to my REF electrode.

I would appreciate advice on why this happened, what I can do, and what tests I can carry out to evaluate the cause.

White film on gelfree electrodes – cleaning and maintenance advice

JAraneda — Mon, 19 Jan 2026 13:18:50 +0000

Hello OpenBCI community,
I’m using an OpenBCI All-in-One Gelfree Electrode Cap Bundle, and after several sessions I’ve noticed the formation of a white / opaque film on the metallic surface of some electrodes.
This film:

Appears after normal use (EEG recordings)
Does not come off with isopropyl alcohol
Looks like a thin mineral or oxidation layer rather than dirt
I suspect it could be related to sweat residues (salts) or mild surface oxidation, but I’d like to confirm.

I have a few questions:

Is this a known or expected effect with gelfree electrodes after repeated use?
What is the recommended cleaning procedure in this case?
Is it safe to occasionally use a diluted vinegar (acetic acid) solution, followed by distilled water, to remove this film?
At what point should this be considered normal wear vs. electrode degradation affecting impedance and signal quality?

For context:

Electrodes are cleaned after use
Stored dry

Any guidance from OpenBCI staff or experienced users would be greatly appreciated.
Thank you in advance!
Best regards,
Juan

Thinkpulse: signal quality, default settings & impedance ?

uditkumar007 — Fri, 19 Dec 2025 20:56:32 +0000

Hi Team,

I’m using ThinkPulse active electrodes with an OpenBCI Cyton board (Ultracortex setup). I want to know if there's a default configuration that you recommend for a clean starting point before troubleshooting.

Problem:
My ThinkPulse sensors are connected to the Cyton board correctly, but when the sensors are not touching my scalp (they’re away from my head, still connected to the board). Even in that “no contact” case, the Open BCI GUI is showing low impedance, which is confusing to me. Because in the Open BCI documentation, it says otherwise. Attached the ss.

Questions:
1. Default baseline settings (before troubleshooting)
What are your recommended OpenBCI GUI hardware settings?
PCA Gain (per channel)
Input Type
SRB2 / SRB1
Bias include (on/off) and any guidance about the bias earclip

2. Impedance behavior with ThinkPulse active electrodes
Is the OpenBCI GUI impedance reading reliable with ThinkPulse active sensors?
Is it expected to see “low impedance” even when electrodes are not in contact with the scalp (but still connected and powered)?
If impedance isn’t reliable for active sensors, what should I use instead as the contact-quality indicator?

3. How to verify that we are receiving good quality signals if the impedance test is not viable
What are your recommended practical tests to verify:
each channel is connected correctly,
electrode contact is good,
signal quality is good and not just noise?

If there’s a specific way you recommend verifying channels one-by-one and validating them, please share that procedure.

Thanks a lot.

Best regards,
Udit Kumar Das

cEEGrid Adapter to ADS1299EEGFE-PDK – selection of connectors MB1-120, M20-8891045, PCB, pins

Susannna — Sun, 28 Dec 2025 18:15:46 +0000

Hi,
I’m working on a DIY project, and I want to make a simple adapter to connect Open-cEEGrid electrodes [https://shop.openbci.com/products/open-ceegrid-replacement-pack]
to the ADS1299EEGFE-PDK board [https://www.ti.com/tool/ADS1299EEGFE-PDK].
Adapter concept (based on the project https://github.com/MKnierim/openbci-ceegrids):
Edge connector for the thin cEEGrid tip (pads 1 mm pitch, flex thickness ~1.57 mm): Samtec MB1-120-01-F-S-02-SL
[https://pl.farnell.com/samtec/mb1-120-01-f-s-02-sl/card-edge-conn-single-side-20pos/dp/2856124]
Output to wires for ADS1299: Harwin M20-8891045 – 10-pin right-angle SMD header, 2.54 mm
[https://pl.farnell.com/harwin/m20-8891045/connector-header-10pos-2-54mm/dp/3225978]
To connect this, some kind of PCB would be needed. From what I see, you can order one from JLCPCB if you have a finished design:
https://github.com/MKnierim/openbci-ceegrids/tree/main/pcb
or, for now, buy some kind of universal prototyping board with SMD/THT pad grids?
Questions:
Does the MB1 + M20 selection make sense? Where am I making mistakes?
Will the MB1-120-01-F-S-02-SL grip the cEEGrid? I measured ~2.1 mm pitch (not 1 mm?), the flex is very thin.
Is the M20-8891045 a reasonable replacement for the original gold-pin header in the OpenBCI project?
Which pin connections should be used (which 10 out of the 20 MB1 → M20)?
Below are links to descriptions of a project using similar connectors: https://pmc.ncbi.nlm.nih.gov/articles/PMC9529594/

ThinkPulse Active Electrodes on Cyton:Excellent Impedance but Persistent Near-Railed / Railed Signal

juanvic5185 — Wed, 17 Dec 2025 22:16:41 +0000

Hello OpenBCI team,

I’m writing regarding a persistent issue using ThinkPulse active EEG electrodes with a Cyton board.

Despite correct placement and consistently excellent impedance values (typically 4–10 kΩ across channels), the EEG signal is almost always flagged as “Near Railed” or “Railed,” with rail percentages frequently exceeding 80–100%. The waveform appears compressed/clipped rather than physiological, and uVrms values are abnormally high.

This occurs across multiple channels and sessions and does not improve with repositioning, re-referencing, or impedance optimization. The contradiction between low impedance and severe rail saturation suggests an input range / gain mismatch rather than a contact or noise issue.

Given that ThinkPulse electrodes are actively amplified and Cyton already operates at a high front-end gain, it appears the combined gain is saturating the ADC input. However, this limitation is not clearly communicated in the ThinkPulse documentation or purchasing guidance, where the system is presented as compatible and relatively plug-and-play.

At this price point, I expected improved signal quality and reduced setup complexity compared to passive electrodes, not persistent rail saturation under normal conditions.

Could you please clarify:

Whether Cyton gain must be reduced or modified specifically for ThinkPulse electrodes

Whether additional attenuation or configuration is required

Whether this behavior is a known limitation of the Cyton + ThinkPulse combination

I’ve attached a screenshot showing excellent impedances alongside severe rail saturation to illustrate the issue.

Thank you for your help and clarification.

Best regards,

ThinkPulse active electrodes, Q&A

dmacd10 — Tue, 02 Feb 2021 22:13:18 +0000

Hi there -

I've recently assembled an ultracortex with the thinkpulse active electrodes. As far as I can tell, I have wired them correctly according to the instructional video. Ear clips are connected to SRB2 and BIAS. The ear clips themselves seem good with an ohmeter, showing ~3ohms at most. I am definitely receiving signal from the thinkpulse electrodes, but if the ear clips are connected to the ears, the signals are all railed. If they aren't, the signal values are huge (100s- to 1000s of uV), noisy, and do not seem to reflect brain waves (not surprising, but demonstrates that the signal wires are connected). The normal spiky electrodes that come with the ultracortex seem to work ok and report reasonable values; I'm using a cyton board which has been working fine with a wet electrode EEG cap.

I feel l'm missing something here....the documentation suggests that the thinkpulse electrodes should be drop-in replacements and have similar signal ranges. I've connected the power supplies for the electrodes to AVDD and AVSS as instructed in the video via the power supply header board, so I'm not really sure what I'm doing wrong. I've tried fiddling with the channel gain settings in the GUI but that doesnt help with railing. Is there some other wiring or ref/bias connection detail I'm not seeing?

Thanks,
Daniel

mixing electrodes

Gaia — Wed, 25 Jun 2025 10:18:54 +0000

Hi everyone,

I’m using the Ultracortex with a Cyton 8-channel board and planning to upgrade to 16 channels. I currently use 8 dry electrodes and want to add gold cup electrodes for better signal quality ,or stress detection.
so I’d like advice on:
Best skin locations for gold electrodes (frontal/parietal)
Whether I can place them around the eyes ? and is it good idea mixing dry and gold electrodes?

Can I use medical ear clips to replace Earclip Electrode?

profeell — Sat, 21 Jun 2025 03:12:22 +0000

The Earclip Electrode I bought from you last time is broken again. I want to ask, I have found many medical ear clip electrodes on the Internet, can they replace the Earclip Electrode? Can you recommend me other products that can replace it? In addition, what is the impedance parameter of this Earclip Electrode?

Copper ring ground?

zotogoweb — Tue, 29 Apr 2025 11:43:49 +0000

Hello. I'm working with a subject who cannot tolerate the clips to ground the Ganglion properly. I was thinking that perhaps a large copper ring soldered to the end of the ground wire (instead of the clips) might work to properly ground the unit. Can anyone advice me before I cut my ground wires and test out the theory?

pre-sales question on ThinkPulse Active Electrodes

AlMuhanad — Tue, 25 Feb 2025 20:28:52 +0000

I have some questions about OpenBCI products, and I hope someone can help me.
Right now, I have the Gelfree BCI Electrode Cap Kit with the CytonDaisy 16-channel board.
I want to upgrade my setup, so I'm considering an upgrade to the ThinkPulse Active Electrodes kit, alongside the UltraCortex Mark IV EEG Headset .
1) Can the active electrodes be connected directly to a DAQ (Humusoft MF644) without using the CytonDaisy board?

2) If yes in (1), I want to ask how large is the raw output signal coming from the ThinkPulse active electrodes?

EEG Newb Question: EEG snap electrodes vs Gold Cup electrodes

idiomancy — Sun, 10 Nov 2024 21:54:42 +0000

I purchased the Low Cost Biosensing Bundle , which contains so called "snap EMG/ECG cables" but which have specific "EEG snap electrodes". This is kind of mixed messaging. It seems to be claiming that the comb shaped snap electrodes are superior for use in areas with hair. However, elsewhere I have seen it claimed that Gold Cup electrodes are the standard for EEG.

So which is it? Which is better? Snap EEG Electrodes or Gold Cup? What about for areas with hair? Can you mix the two?

Bonus question:
What kind of tape is supposed to be used with gold cup electrodes that I see in everyone's pics?

References:
bundle -
https://shop.openbci.com/products/low-cost-biosensing-starter-bundle

eeg snap electrodes -
https://shop.openbci.com/collections/frontpage/products/emg-ecg-snap-electrode-cables?variant=32372786958
https://shop.openbci.com/products/eeg-snap-electrodes

gold cup electrodes -
https://shop.openbci.com/collections/frontpage/products/openbci-gold-cup-electrodes
https://shop.openbci.com/products/ten20-conductive-paste-8oz-jar

Dry/reusable EMG electrode

jediknightnapoleon — Mon, 11 Nov 2024 19:41:32 +0000

Hi,
Does anyone know if there are still commercial dry/reusable EMG electrodes compatible with openBCI that can be purchased? I saw there's a IDUN dryode in the openBCI shop page but it's sold out. When i check IDUN they seem to have deleted it as a stand-alone product...
Thanks in advance!
Jerry

Daisy board showing different signal than cyton for the same channel & wires.

ssaxena — Wed, 06 Nov 2024 05:39:55 +0000

Hi,
I have observed some discrepancy in signal data from daisy board. When I connect a channel into cyton board the signal appears to be much more clearer than same connection in daisy board. Daisy board is showing higher amplitude range for almost all channels and also higher frequencies for some of them. When the same channel is plugged into cyton board, the signal appears to be smoother, relatively low amplitude range and frequency to some extent.
What could be the possible reasons for this?
Thanks.

Upgrade to active electrode setup from a passive one

ssaxena — Mon, 21 Oct 2024 12:58:00 +0000

I had purchased https://shop.openbci.com/products/all-in-one-gelfree-electrode-cap-bundle. It comes with a Cyton Daisy Board, EEG Cap, and necessary wires, etc. It is a setup for Passive electrodes. How do I convert it to an active electrode setup of 16 channels? What all will I need?
Also, What other gel-based electrodes are compatible with this setup?
Are gel based electrodes better than active dry electrodes?

How to Extract Electrode Impedance Values with UNIX Timestamps?

statius9 — Wed, 11 Sep 2024 14:52:14 +0000

I need guidance on extracting impedance values with corresponding UNIX timestamps. What methods or tools should I use to ensure both data points are captured accurately? Any help would be appreciated! For instance, is there a wiki, documentation, or another discussion post I can refer to.

implant synchron or stentrode how to detect?

Unger — Sun, 08 Sep 2024 16:57:26 +0000

bci technologies are developing and may have started their testing long before this was published on the internet. Synchron or stentrode implant what kind of examination can detect? It is in the jugular vein and a regular MRI may not show it.

The electrodes lose their connection in the middle of the session.

bathiya — Thu, 15 Aug 2024 07:34:47 +0000

Device information
we purchased open bci cyton board with 8 channels and open bci headband kit.
When we record EEG signals from a person, the electrodes placed on the forehead often become "railed,". Despite adjusting the electrodes to ensure they make proper contact with the skin, the issue persists and they do not stop railed. Often the same problem happens in other electrodes too.
How to overcome this issue.

Ultracortex replacement electrodes ?

Koreanstudent — Fri, 09 Aug 2024 08:32:28 +0000

How do I purchase assembled electrodes like the photo above?

Amplitude if I use 16ch weaker than 8ch

hiro — Mon, 27 May 2024 15:30:27 +0000

Hi all,
I did simple experiment, comparing amplitude of waves between 8ch and 16ch. I used a default electrode and Gain was 8x because I also use ThinkPulse active electrodes. I used only electrode at Fp1. Other settings were default. The first image shows a wave with 8ch.

Similarly, the second shows a wave with 16ch.

Although amplitude was around 15uV when I used 8ch, amplitude was only 7~8uV when I used 16ch. I only changed whether Daisy board was active or not. I did not modify any other software and hardware settings. Do you know why it happens? Intuitively, I guess that amplitude with 8ch was fine but when I used 16ch, amplitude was nearly half the size of it.

Search for Zengar Electrodes

Sp87 — Mon, 20 May 2024 09:56:22 +0000

Good morning!

Do you know where I can find Zengar's electrodes? I have a neuroptimal® and I don't get electrodes, because they don't let them send,

Do you know of any distributors in Europe?

Thank you

Active Electrode Circuit Design

biomurph — Wed, 28 Jan 2015 00:34:09 +0000

Hey,

Starting a thread here about the best way to go about designing active electrode circuitry. From what I understand, placing an active (op amp or other) device in very close physical proximity to the contact site improves noise reduction and allows for a dry contact between the electrode sensor (gold, silver, Ag-Cl, etc) and the subject scalp.

My basic reference for this is the active electrode circuit published by Olimex

https://www.olimex.com/Products/EEG/Electrodes/EEG-AE/resources/EEG-AE.pdf

I've used these, and they perform quite well with OpenBCI (5V differential between AVDD and AVSS to power).

The basic shape of the thing has

TVS and Diode suppression on both ends

Power supply decoupling and zener protection on the V input

Some impedance added to the input and output

High Frequency rejection filter on the op amp

but beyond that, it is just a unity gain follower.

Of course, the specs of the op amp are going to play a very important role:

high impedance inputs

high CMRR

low equivalent input noise at low frequencies

My question is, what about the basic circuit, besides the op amp selection ('tho that could enter this discussion) stands to be improved? Or discarded?

advantage of "linked ears" reference vs single reference?

dave12 — Mon, 04 Mar 2024 16:49:35 +0000

Hi,
I am looking to understand the advantages of 2 linked ears reference over just 1.
Isn't one enough to help cancel the EMF for the electrodes on the head anywhere? Or is there a phase difference in the EMF activity with only a short distance, from left to right part of the head?

cEEGrid and P300 speller

etc — Wed, 14 Feb 2024 18:18:13 +0000

Sorry for my english and for the question... .
I read on your website something about your cEEGrid. Do you think that is it possible to use cEEGrid with a P300 speller?
If the question is stupid, I am sorry!!!

How far apart do ground, ref, and signal electrodes have to be?

hp132 — Wed, 21 Feb 2024 06:10:09 +0000

Typically I've seen ground and reference attached to the earlobes but if I were to place all three electrodes (ground, reference, and signal assuming a single-channel system) right next to each other, would there be any deterioration to the signal quality?

Replacing spiky with 5mm comb electrodes on ultracortex mark IV

mkcyeung — Mon, 31 Jul 2023 18:21:38 +0000

Hi,
I just got the ultracortex mark IV and some dry comb electrodes. How can I replace the default spiky electrodes with the comb ones? Thank you!
Michael