Placing of Reference Electrodes for M. Biceps Brachii (EMG)

[Luki]

Hi Coen and BioSemi community,

where would you suggest to place the DLR and CMS electrodes for investigating EMG signals of the Biceps Brachii? The only resource I could find on the BioSemi page about this is the following:
http://biosemi.com/faq/cms&drl.htm

However, it focuses on EEG and recommending the CMS electrode being close to the electrodes... Placing the EMG array over the Biceps with the reference electrodes being on the Olecranon (elbow, bony part) and the other one close to the EMG electrodes leads to a rather low signal to noise ratio. Thus, there is a high 50Hz noise in the signal.

Could you suggest a set up for my purpose in more detail?
Thanks in advance!

Kind regards,
Lukas

[Coen]

Locate the CMS in the center of the EMG electrodes, DRL can be anywhere.

Bundle and twist the wires to prevent 50 Hz. When measuring with bipolar pairs, twist the wires of each pair.

Best regards, Coen (BioSemi)

[Luki]

Unfortunately, I can't place the CMS electrode in the centre of the EMG electrodes as the set-up is an electrode array (4*16) with an inter-electrode distance of 4mm in the x- and y-direction.
Where should we place the reference electrode in this case? Furthermore we cant twist the cables as the electrode array and its wires are designed on a FPC. Is there another possibility to increase the signal to noise ratio (especially at 50Hz) or would you rather recommend to totally change the set up and use other electrodes?

Thanks for the input so far!

Cheers,
Luki

[Coen]

Locate the CMS near the array.

Use shielded wire for your array.

Change to our Active EMG array (128 channel miniature preamp a few cm from the array), email to info@biosemi.com if you are interested (our current active EMG array is not yet featured on our website).

Best regards, Coen (BioSemi)

[Luki]

Thanks, just one more question. When the DRL electrode can be anywhere, what is this electrode important for then?

[Coen]

http://www.biosemi.com/faq/cms&drl.htm

[baptiste]

Hello.
On a related note, if I am recording from the 2 forearms (to get left and right hands EMGs), where should I put the CMS?
Thanks a lot,
Baptiste

[Coen]

CMS and DRL on the torso, best regards, Coen (BioSemi)

[baptiste]

Ok thanks.