Application of a New Graphical Fitting Approach for Data Analysis in Electrochemical Impedance Spectroscopy

✍ Scribed by Andree Schwake; Holger Geuking; Karl Cammann

• Publisher: John Wiley and Sons
• Year: 1998
• Tongue: English
• Weight: 85 KB
• Volume: 10
• Category: Article
• ISSN: 1040-0397
• DOI: 10.1002/(sici)1521-4109(199810)10:15<1026::aid-elan1026>3.0.co;2-h

✦ Synopsis

A new grahical method for analyzing impedance data presented in the complex plane plot is introduced. The advantage of our approach is that it can be employed easily with commonly available spreadsheet calculation software like Microsoft Excel, beneficial when no CNLS software is available.

A semicircle in the complex plane plot is defined by three points of the circumference. Knowing the trigonometric function, the radius, e.g., representing the bulk resistance of ion-selective membranes, can be calculated easily. The error of the data fit is determined by considering the standard deviation of the data points referred to the fitted semicircle. The capacitance of the system under investigation can be calculated by plotting the real part of the impedance against the angular frequency. If the equivalent circuit is known it is possible to obtain the value of the capacitor by employing the nonlinear least square method. The applicability and efficency of our method has been verified by analyzing networks and impedance spectra of ion-selective polymer matrix membranes. The results of our method were compared with those obtained by applying the CNLS method.