multiple EMG common ground [Cyton]
matt_higger
boston
in Cyton
I'm interested in measuring 8x EMG channels which all share the common ground. My goal isn't to characterize a single muscle but to get as rich a dataset as I can (per electrode placement) so I may estimate which movement a user is making (from some discrete set of arm movements). In other words, I don't mind that I can't isolate a single muscle if I can reduce setup time by a few electrode placements.
- Is it sufficient to just wire N1P, N2P, ..., N8P together and connect to a single electrode? (And if so, is there some clean connector which avoids a bird's nest of wiring?)
- Will I get a bunch of heart artifacts if the common negative node is on another arm from a positive node?
- Does anybody have an idea as to why this decision might haunt me later on in the project?
Comments
Also, thank you to the whole community of folks here! I suspect that your collective experience will save me many a headache down the road.
Matt, hi. The default configuration of the Cyton uses SRB2 (closest to board pin), as the common reference for IN1N, IN2N, ... IN8N pins (all closest to board). This is the setup used for EEG. So there is no need to manually wire IN1P, IN2P, ... IN8P pins (all farthest from board) together; that is already the default condition presented on SRB2.
William
Also, to distinguish, in EEG / EMG / ECG, 'Ground' lead is what is labeled 'Bias' on the Cyton board. SRB2 is termed 'Reference', the common reference. Ground is a wire that helps to reduce noise from mains / AC voltages present in all environments.
William, thanks for your insight. Using the default configuration is certainly easy to do.
Best
-Matt
@wjcroft Thanks for clarifying this! Good for everyone to know.