The importance of using four-terminal sensing for EIS measurements on low-impedance systems

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Electrochemical impedance spectroscopy (EIS) is used to study all types of electrochemical systems. The internal impedance of the device under test (DUT) can be very small (i.e. a commercial battery), or very high (i.e. a metal substrate with a non-conductive coating). This application note describes the implications of connecting the DUT in a two terminal, versus four terminal, configuration, and shows how the impedance of the cell cables may interfere with EIS measurements on low-impedance DUTs.