Electrochemical impedance spectroscopy dielectric constants

In electrochemical impedance spectroscopy (EIS) measurements a membrane is placed in an electrolyte solution of specified concentration. Two electrodes are located on the membrane surface, and a small alternating current of known frequency and with small amplitude is applied to the system. The phase difference and the amplitude of the simultaneous electrical potential that develops across the membrane are measured. A wide frequency range is used in the measurements, and the membrane is assumed to be a plane capacitor. As a result, the resistances and capacitances of the membrane are obtained and the thickness of the membrane can be evaluated. By using knowledge of the dielectric constant of water and the membrane material, the porosity of the membrane can be evaluated from the capacitance values. Impedance can be calculated from the values for resistance and... 

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