ECG Artifacts + Muscle Contamination in simultaneous acquisition of EMG and EEG using Cython + Daisy

Hi everyone,

We are writing because we had some issues trying to use Cython + Daisy to simultaneously acquire EMG and EEG following this tutorial:
https://docs.openbci.com/GettingStarted/Biosensing-Setups/ExGSetup/

For EMG, we attached two electrodes to the arm following the recommended layout described in the EMG tutorial and we connected them to the top and bottom pins of N16P (Daisy). The remaining electrode (electrode) was connected to AGND. For a one-channel EEG, we employed the N1P bottom pin of Cyton board. The two ear clips were connected to SRB and BIAS bottom pins.

With this setup, we encountered the issue of ECG artifact being clearly visible in the recording, especially in the EMG channel. Additionally, when contracting the muscle, muscular activity bled into the EEG channel (see attached images). Neither of these activities was visible in the video available in the tutorial.

Another test conducted: Recording only EMG, connecting the elbow electrode to the BIAS pin. In this case, the ECG was not visible.

We wonder if there is a more optimal way to acquire EMG + EEG on the same board that we can use or if there is any error in the interpretation of the tutorial.

Thank you!

(The first image corresponds to the muscle at rest and the second after flexing the muscle.)

Comments

  • wjcroftwjcroft Mount Shasta, CA

    The info about AGND on that tutorial is wrong. There should be NO AGND wire connect to the subject.

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