Does Cyton - Ultracortex Mark IV uses active referencing?

PGameface

Hi,

I'm completely new to BCI. So pls bear with me if the questions are basic.
I've read that some EEG systems send small currents to the electrodes - which could also pass through the head - such as for 'active referencing' - which as I understand is used to neutralize the potential difference between the electrode and the skin in order to get a stable electrode-skin impedance.

Does the Cyton - Ultracortex Mark IV uses such a technique? Or generally, does it send any current to the electrodes at any point in the EEG measurement process?

Regards,
PG

wjcroft

Cyton and Ganglion are PASSIVE electrode systems, not active. No current is being sent to the electrodes that can "pass through the head". On the other hand some active electrodes are available in the Shop at extra cost.

https://shop.openbci.com/products/thinkpulse-active-electrode-kit

William

PGameface

Thanks for clarification. I've a few more questions.

1. Are the Dry EEG 5mm comb electrodes essential for higher signal quality for UCM IV?
2. Are the above electrodes easily deployed in the pro assembled UCM headset? Or do we need an unassembled one? Are there any specific tutorial on installing the comb electrodes?
3. The dry electrodes inbuilt in UCM IV has any maintenance regimen (like cleaning with water etc) for longer durability like for the 5mm comb electrodes? Also usually how many uses can these inbuilt electrodes take without any signal degradation?

wjcroft

@PGameface said:
...
1. Are the Dry EEG 5mm comb electrodes essential for higher signal quality for UCM IV?

I believe the UC default comb electrodes are the shorter 'spikey' combs, just a couple mm long, not 5 mm. You can replace these using a screwdriver with the 5mm combs. Depending on the type of hair on the subject, the 5mm may work better. But many have gotten good results with the spikey combs as well.

2. Are the above electrodes easily deployed in the pro assembled UCM headset? Or do we need an unassembled one? Are there any specific tutorial on installing the comb electrodes?

The dry electrodes are just screwed in place.

3. The dry electrodes inbuilt in UCM IV has any maintenance regimen (like cleaning with water etc) for longer durability like for the 5mm comb electrodes? Also usually how many uses can these inbuilt electrodes take without any signal degradation?

Here are some cleaning instructions for the comb electrodes. Note that the default spikey combs last longer than the 5mm combs.

https://shop.openbci.com/products/5-mm-spike-electrode-pack-of-30

William

PGameface

Thanks.
Is the UC suitable for regular use? as compared to the saline/gel electrode caps?
I'm looking at a trade off between lesser maintenance of the dry electrodes and higher signal quality for the wet electrodes. But I wanted to try the headgear which is recommended for regular use.

wjcroft

The Ultracortex headset is very fast to apply or remove. The default spikey electrodes are low / lower maintenance than the 5mm. Any wet / saline / paste / gelled electrodes take much longer to apply / remove / clean.

PGameface

Ok Thanks