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I've been trying to understand the following electrochemical test strip in a simplified self-biased configuration diagram:

two electrode test strip

It appears to be an inverting op amp filter circuit but then gain = - Rs/0 = infinity!!

Given it appears to be a unity gain op-amp based on Vout, there must be a matching impedance in the electrode strip (e.g. link) but I am lost as to how Maxim determines Vout.

Can anyone help?

ocrdu
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SeanJ
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    @user263983 I don't think so, Vout = Vb + (IsrRs) – SeanJ Nov 30 '21 at 00:35
  • There is "Is", that will make Vout = Vb + Is x Rs, regardless of the gain, as long as the OPA covers the range. The circuit you draw is intended to measure the resistance of the TWO-...STRIP. So, Is = Vb / R_TWO..._STRIP. – jay Nov 30 '21 at 01:30
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    Go look up transimpedance amplifier. It should all become clear when you do. – Andy aka Nov 30 '21 at 06:38

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