Three electrode measurement for AD5933?

Hi everybody,

 

we're using the AD5933 for bioelectrical electrode impedance measurements. Usually, the electrodes have to be immersed in a saline solution for measuring, and a 2 point measurement (Electrode to Reference electrode) adds unwanted potential offsets to the measurement. For a more accurate measurement, a technique using 3 electrodes is employed:

 

(Fig. 4 from this link)

Ralph Group : projects : Fabrication and characterization of graphene electrodes for electrochemistry experiments

Figure 4

Is there any way to connect the AD5933 in such an arrangement to measure impedance? Do you have any additional suggestions for performing such a measurement?

 

Thanks and Kindest Regards,

Oscar Cota

Parents
  • Hi Miguel,

    ok, right now we're trying basically your circuit, without the transistor (too simple, I know), hoping that the OpAmp supplies whatever required current for the sensor to produce the desired VREF.

    Since we're working with low stimulation currents (around 100 uA), might be that we don't need the extra driving.

    If it doesn't work, we're going to put the transistor.

    Thanks and kind regards!

    Oscar

Reply
  • Hi Miguel,

    ok, right now we're trying basically your circuit, without the transistor (too simple, I know), hoping that the OpAmp supplies whatever required current for the sensor to produce the desired VREF.

    Since we're working with low stimulation currents (around 100 uA), might be that we don't need the extra driving.

    If it doesn't work, we're going to put the transistor.

    Thanks and kind regards!

    Oscar

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