Introduction
Electrochemical Impedance Spectroscopy (EIS) is an electrochemical technique with
applications in corrosion, biosensors, battery development, fuel cell development, paint
characterization, sensor development, and physical electrochemistry. EIS can even be used
to test the freshness of fish! (J. Food Science, 65, 780 (2000)) The reason for this popularity
is the high information content of EIS. EIS provides a more thorough understanding of an
electrochemical system than any other electrochemical technique.
Why is EIS so powerful? Because the EIS experiment involves the application of a sinusoidal
electrochemical pertubation (potential or current) to the sample that covers a wide range of
frequencies. This multi-frequency excitation allows (1) the measurement of several
electrochemical reactions that take place at different rates and (2) the measurement of the
capacitance of the electrode.

For an excellent introduction to EIS, see our Basics of EIS Application Note. The Reference
Section at the end of the EIS Application Note contains additional material that will be useful
to you. If you have any questions on EIS, you'll find that your friends at Gamry are a wealth
of information. Call our support team if you'd like discuss the theory or the applications of
EIS.