What is Ground Electrode in EMG?
*Learning about EMG as a part of our research. My team has at least some experience with electronics that is worth mentioning, but don't have any experience with EMG/bio-potentials. Most EMG hardware is designed without a ground electrode, but an engineer basically recommended using a ground electrode as well "like used in EEG".
What is ground electrode in EMG and what do the circuit design(s) look like? Can any operational amplifier be used?
Any recommended resources that outline the design of such hardware?
2 answers
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| User | Comment | Date |
|---|---|---|
| tilly | (no comment) | Aug 31, 2023 at 10:01 |
CMRR design is key to rejecting grid e-fields that impose noise onto EMG, EKG,EEG amplifiers. This includes all series Zs of cable balance and Amp CMRR. For this reason >100 dB CMRR are required using INA's and not OA's with 1% R's (-40dB error).
The same CMRR matching is required on 60/50 Hz LPF components on the signal conditioners.
RLD feedback is commonly used to improve CMRR by creating a virtual ground from CM signal error feedback.
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When measuring signals at different points on the skin of the body, you don't usually want to connect the victim patient to ground. Usually you use an extra electrode connected some distance away that is driven by the circuitry to the average of the other signals. That reduces the common mode range of the other signals, and cancels out some of the common mode signal. This is often called the "right leg driver" for EKGs. EEGs don't do it exactly like that, but the general concept is still valid.
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