I want to measure the change in impedance of any material when i'm switching it between different relative humidity (RH%) solution . Although i read some papers on it but not able to understand how to perform this experiment using Auto-Lab potentiostat/ galvanostat/ EIS analyser. Plz help me to sort the problem out.
In order to understand how to measure the impedance of a material let us model electrically a piece of material in form of a slice supplied by two metallic electrodes.
If the electrodes constitutes negligible impedance then the impedance of the structure will be that of the material specimen. Assuming the material is a dielectric, it will have a capacitance C in parallel with a resistance Representing the electrical losses in the specimen.
Such impedance can be measured by many methods. All of them can be divided into null type bridge measurement and I/V deflection measurement.
The I/V deflection measurement is straight forward where one injects AC constant current in the specimen and measures the vector voltage across it by a vector impedance meter,
Then one can calculate the magnitude of Z from the magnitude of the voltage divided by the current injected, that is , mag Z= mag V/ I,
and the phase of the impedance phi= phase of the measured vector voltage.
One can further calculate R and the reactance X of the specimen. And finally the capacitance of the specimen.
Other way one can apply AC constant voltage voltage source on the specimen and senses the vector current across it. Then one can magnitude of the impedance and its phase. but this time the phase of the impedance is the negative phase value of the current.
For more information about impedance measurements please follow the paper in the lin:https://www.researchgate.net/publication/301644918_Four_Voltmeter_Vector_Impedance_Meter_Based_on_Virtual_Instrumentation?ev=prf_pub
wish you success
Article Four Voltmeter Vector Impedance Meter Based on Virtual Instrumentation
Thanks sir for your kind and prompt help. I'll go through the paper and try to find out the solution.
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