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)
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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,
I add some extra info I have researched to see if somebody could help us. Here's one schematic of what the lab equipment does to measure electrode impedance. There is a stimulation voltage Vin that generates a current i, which is measured at a TIA. However, Vin is not directly applied to the electrode, but to a control loop that ensures that Vref=Vin. Therefore, Vin is between Vref and Virtual GND (working electrode). The impedance contribution of the counter electrode is thus eliminated.
(Source: E760 - Lectures on Electrodes I - Martin Schüttler . University College London 2009)
Do you think such arrangement is feasible with the AD5933?
Cheers and Kind Regards,