1. ABU BAKAR abubakarmehmood786@yahoo.com +92 322 7967172

2. ABU BAKAR abubakarmehmood786@yahoo.com +92 322 7967172

3. Electrochemical Impedance Spectroscopy (EIS) Basics

4. ABU BAKAR abubakarmehmood786@yahoo.com +92 322 7967172 Introduction Syed Taha

5. ABU BAKAR abubakarmehmood786@yahoo.com +92 322 7967172  This description of resistance via Ohm's law applies specifically to direct current (DC), where a static voltage or current is applied across a resistor.  Impedance, by contrast, is a measure of the resistance a circuit experiences related to the passage of an alternating electrical current (AC).  In an AC system, the applied signal is no longer static but oscillates as a sinusoidal wave at a given frequency.  The equation for impedance is analogous to Ohm's law; however, instead of using for resistance we use for impedance Continue….

6. Figure 1.2 Simplified Electrochemical Impedance Spectroscopy Diagram. If the input signal is potential, then the green wave represents the input sinusoidal potential signal and the red wave represents the output sinusoidal current.

7. Figure 1.3 Simplified Electrochemical Impedance Spectroscopy Diagram with Phase Angle. The teal sinusoidal wave represents input potential signal visually overlapped in time with the output current signal. Phase angle represents the shift in phase when the input and output signals are overlapped in time.

8. ABU BAKAR abubakarmehmood786@yahoo.com +92 322 7967172 EIS Example…  A complete EIS experiment consists of a sequence of sinusoidal potential signals centered around a potential setpoint.  The amplitude of each sinusoidal signal remains constant, but the frequency of the input signal will vary.  Typically, frequencies of each input signal are equally spaced on a descending logarithmic scale from ~10 kHz - 1 MHz to a lower limit of ~10 mHz - 1 Hz.  For each input potential, a corresponding output current is measured at a given frequency. Qandeel Ali

9. Figure 1.4 Visualization of EIS experiment. The applied input signal and measured output signal have the same frequency.

10. Figure 1.5 Lissajous plot where the input potential and output current are perfectly in phase. The resulting curve is a straight line with a slope proportional to the impedance at that frequency.

11. Figure 1.6 Lissajous plot where the input potential and output current are out of phase. The resulting plot is an oval.

12. ABU BAKAR abubakarmehmood786@yahoo.com +92 322 7967172 EIS Instrumentation Zeeshan Haider

13. ABU BAKAR abubakarmehmood786@yahoo.com +92 322 7967172 Basic Principle:-

14. ABU BAKAR abubakarmehmood786@yahoo.com +92 322 7967172 Application of EIS:-

15. ABU BAKAR abubakarmehmood786@yahoo.com +92 322 7967172 Bode plot Mian Ahmer Figure 2.3 Plotting of Impedance Magnitude and Phase Angle in Polar Coordinates

16. ABU BAKAR abubakarmehmood786@yahoo.com +92 322 7967172 Continue… If we move from polar to cartesian coordinates, we can break the impedance magnitude into its x and y components (Figure 2.4).