EMG from Hand Muscles

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a.h.javadi@gmail.com
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EMG from Hand Muscles

Post by a.h.javadi@gmail.com » Wed Feb 24, 2010 9:19 pm

Hi :-)

I want to record flexor digitorum muscle (simply muscle to control fingers on top of the forearm). How should I setup the system? Where should I put CMS and DRL? Once I tried to simply put CMS and DRL somewhere on the forearm close together but I couldn't reduce the impedance to achieve steady blue light, so finally I applied conductive gel on the participant's hand and put the two CMS and DRL electrodes both on the same gel. Well, it is stupid, but at least let me record data which is not meaningful at all. Any suggestion? very many thanks :-)

Have a good time :-)
Amir

Coen
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Post by Coen » Thu Feb 25, 2010 7:13 pm

Do not short the CMS and DRL with a gel bridge, since this will reduce the Common Mode Rejection Ration with 40 dB

Locate the CMS in the vicinity of the EMG electrodes (but prevent gel bridges)

The DRL electrode can be located anywhere on the body, for example on the lower or upper arm.

The DRL needs a low impedance connection to the body (the other electrodes are much less critical). Try to massage the gel a bit into the skin if you have trouble getting a steady blue light.

Best regards, Coen (BioSemi)

a.h.javadi@gmail.com
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Location: UK

Post by a.h.javadi@gmail.com » Fri Feb 26, 2010 10:22 am

Dear Coen

Very many thanks. It works. It was difficult to get a steady blue light with DRL placed on the arm, but I finally got a steady light when I put it on the back of the arm or on the fingers. Thanks again.

Have a good time,
Amir

schen
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Joined: Mon Feb 11, 2013 9:16 pm

Re: EMG from Hand Muscles

Post by schen » Tue Feb 12, 2013 7:12 pm

I have a similar question, so I am posting it here in this topic. I am recording EMG (no EEG, so no headcap) from corrugator and zyg major muscles with bipolar placement. I just received my order of flat-type CMS/DRL electrodes and tried running a session with these placed on the mastoids. The signal was very noisy, although I got a stead blue light. I saw the suggestion to place the DRL on the arm, but am not sure if the electrode will reach since the CMS and DRL are connected on the same aux cable. What do you suggest? Was the mastoid placement a bad idea?

Thanks so much,
Stephanie

Coen
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Re: EMG from Hand Muscles

Post by Coen » Wed Feb 13, 2013 2:59 pm

When measuring face muscles, locating CMS and DRL on the head is OK. Locating CMS on the mastoid may not be optimal because the jaw muscles may cause increased Common Mode. Locate the CMS in the center of the other electrodes.

Make sure you look at bipolar leads (referencing in software) to reject Common Mode. Interference in the unreferenced data is normal.

Best regards, Coen (BioSemi)

celineramdani
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Re: EMG from Hand Muscles An other problem !!!

Post by celineramdani » Thu Aug 14, 2014 12:48 pm

Hi,

I want to record EMG only, on hands (movement recording of the first finger EX1-EX2 on the left hand and EX3-EX4 on the right hand). I use a flat-type CMS/DRL electrodes.
I have made several recordings without any problem and since 15 days, I can't get an EMG signal. Nothing have been changed. I have something on my computer, so the optical fiber seems to be ok, when I try an other EX elecrtode nothing change. Without CMS-DRL many spikes appear on the signal and with CMS-DRL I have only une straight line, spikes dissapear. Muscles activation don't modify the line.
I don't know what to do !
Please help me because my experiment is not over and I have a second to start on september with EEG and EMG.

Best regards

Céline

Coen
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Re: EMG from Hand Muscles

Post by Coen » Thu Aug 14, 2014 1:42 pm

Is the blue light blinking during the recording ? If yes, then test as described on http://www.biosemi.com/faq/check_electrodes.htm . Then replace defect electrode(s).

Best regards, Coen (BioSemi)

hannah
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Re: EMG from Hand Muscles

Post by hannah » Mon May 18, 2015 11:10 am

Dear BioSemi,

I have a somewhat related question, so I will post it here. In our lab we are currently measuring GSR with two electrodes on the finger tips of the left hand in combination with a flat CMS/DRL electrode. My question regards the placing of the CMS/DRL electrodes: initially we tried to place them on the back of the left hand (so close to the GSR electrodes), but we can only get a steady blue light if we use abrasive gel on the back of the hand, which we would rather not do. What seems to work (in the sense that the blue light is steady) is to place the CMS/DRL on the forehead instead. My question is whether this is an acceptable placement of CMS/DRL if we want to measure GSR or whether the CMS/DRL electrodes have to be closer to the GSR electrodes to obtain a good measurement.
Thank you in advance for your answer!

Best,
Hannah

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Re: EMG from Hand Muscles

Post by Coen » Mon May 18, 2015 11:35 am

The location of CMS and DRL does not influence the GSR result.

Best regards, Coen (BioSemi)

hannah
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Re: EMG from Hand Muscles

Post by hannah » Mon May 18, 2015 2:18 pm

Thanks very much for the speedy reply! Good to know we can go ahead as planned.
Best,
Hannah

EJB
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Re: EMG from Hand Muscles

Post by EJB » Thu Mar 09, 2017 12:45 am

Hello! I'm having similar problems to the users above. I'm collecting GSR and my pair of flat CMS/DRL electrodes doesn't seem to connect properly (the blue light is blinking) when applied to the back of the hand, the arm or the forehead. I've tried massaging some gel into the skin beforehand, but it didn't help.

However, it does connect when applied to the inside of the hand or to the cheek (even with only one electrode attached in that location). I wanted to ask whether attaching the electrodes to those sites is acceptable for recording GSR, and if you have any suggestions for why it may be not working in the other locations.

Thanks!

Coen
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Re: EMG from Hand Muscles

Post by Coen » Thu Mar 09, 2017 1:20 pm

The location of CMS and DRL does not affect the GSR measurement (as long as the blue light is continuously ON)

Best regards, Coen (BioSemi)

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