EMG Cable quality and movement artifacts

Started by all315, February 27, 2020, 01:41:07 am

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all315

Hello,

I want to purchase the Shield EKG-EMG with the professional cable.

I need to know if the cable is well isolated from electromagnetic fields and especially if it produces artifacts when moved. This is really important. I don't want that the movement of the cable interfere with the EMG signal.

I have another blasoned EMG sensor that has this problem: when I move "softly" or touch the electrode cable, the EMG signal goes from the minimum value to the maximum, fully covering the EMG signal.

I want to be sure that your EMG-EKG-Cable system has not this problem.

Thank you.

LubOlimex

There shouldn't be such an issue, or at least I haven't noticed such a problem but a lot would depend on your software - SHIELD-EKG-EMG can be used for EMG (Electromyography) as the name suggests. This means that it can literally be used to detect movements of muscles...
Technical support and documentation manager at Olimex

all315

Hello, thank you for the answer.

I'm a psychophisiologist and biofeedback trainer since many years. The emg sensor must detect the muscle contraction (=tension), not the movement of the body. This is an old issue of the older emg devices; for example, if you make an isotonic contraction of your biceps (without moving the arm), the emg sensor (placed on it) should detect that contraction; but if you contract your biceps moving the arm, the emg sensor should detect only the muscle contraction and not the movement of the cable produced by the movement of the arm: if this happens the sensor has produced artifacts.

It is not possible  to erease this kind of artifacts via software algorithms because if the emg system detect the cable movements, the signal (artifact) produced by the cable movements is greater than the signal produced by the muscle fiber tension. There is no way to subtract the former from the last. A similar phenomena happens with the EEG and the artifacts produced by eye movements: the latter dominates the former and there is no way to subtract it.

I know that you are a serious European company and test your products before sell them; this is why I'm asking you if you are really, really shure (not vaguely) that you emg system (emg-ekg device + cable) is subject to this kind of movements artifacts or not. This should be a mandatory feature of any emg system.

With the professional biofeedback devices that I use with my patients I can connect the emg electrodes anywere, run or jump and the system doesn't detects movements artifacts.

As soon as possible I will publish on youtube what happens with the emg kit purchased from one of your blasoned competitor (Mouser asked me to realize the video to see the problem, communicate it to the company and to find a solution; I'll also publish the video on YT for searching help).

Thank you again.