Is this capacitive coupling effects or magnetic field? https://www.youtube.com/shorts/JaT8jT_vL24
In the video above where I was standing about 3.5 feet away from the EEG unit and electrodes connected to it. Whenever I waved my hands, there were large amplitude distortions in the EEG display (zoomed in but still 3.5 feet away). Before and after the waveforms were more uniform and have flatter amplitudes.
Can electric flux from the human body or hands travel 3.5 feet away to affect the electrode wires serving as antenna? What is the magnitude of this electric flux that can do it? Is this called capacitive coupling?  or is the effect somehow magnetic field?
 A: What you're seeing is probably the effect of changing field of electric potential in the room, and thus also changing electrostatic component of total electric field. Moving your body can cause such changes, because potential is not the same everywhere (air is not very conductive), and human body can carry electric charge. I recall that similar effects on oscilloscope can be seen when rubbing your shoes against the floor. It is most probably not caused by induced electric field, this is usually noticeable only at high frequencies and only for some convenient wire geometries (coils).
You can call this effect "capacitive coupling" but that is more of an engineering term for one electric circuit component interacting with another component via electrostatic part of total electric field. Here we have interaction of voltmeter/"oscilloscope in DC mode" with environment in which charges can move.
A: This is actually a type of artifact seen in hospitals when performing sEEG, which I've seen firsthand. I even jumped up and down a few feet from the machines which resulted in similar spikes as you are seeing.
I've been trying to figure out this issue as well, but you are absolutely NOT the only one who has encountered this. Surprisingly, however, I have not been able to locate any useful research.
I'm interested to find an answer as well, so if you've managed to figure anything out, please share!
