Electrode (Ag-AgCl) are placed at different part and directly fed to positive and negative input of differential amplifier. How can we realize human body and amplifying system have same current sink or common reference point(say ground)?

  • \$\begingroup\$ an ideal amplifier passes no current through the input. \$\endgroup\$ – Jasen Jul 31 '19 at 0:31
  • \$\begingroup\$ Also Galvanic skin voltage and capacitance modulated by motion may interfere. along with line stray noise. Common Mode rejection demands use of balanced Differential Instrument Amp designs with shielding filtering and high CMRR and PSRR. When different grounds are common, (connected) chances are greater for stray noise coupling especially if one is earth grounded with a SMPS supply. while other a floating SMPS supply high CM noise. Noise increases which then requires careful understanding of avoiding current flow. Medical supplies must be used or batteries with opto isolation \$\endgroup\$ – Tony Stewart Sunnyskyguy EE75 Jul 31 '19 at 8:24
  • \$\begingroup\$ Use a third wire, attached to the LEG, as the RTN path???? \$\endgroup\$ – analogsystemsrf Jul 31 '19 at 9:27

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