Applications of Electrochemical Impedance Spectroscopy in pH Sensor Characterization and Failure Analysis

pH sensors have been widely used in wet labs in research & development and production lines in various industries. Measuring the potential differences between pH and reference electrodes in pH buffers is usually used for calibration and performance test of a pH sensor. Electrochemical Impedance Spectroscopy (EIS), as a powerful analytical technique, has been used for the study of various electrochemical systems and processes. Nevertheless, the information about EIS study of pH sensors is rarely available from published resources. This work presents: electrochemical impedance spectra of normal pH sensors and sensors with different defects, which result in different failure modes; how EIS can be used to facilitate the failure analysis of pH sensors; how EIS is used to study the aging mechanism of glass electrodes of steam-sterilizable pH sensors. The work has shown that EIS can be used to facilitate the failure analysis of pH sensors by largely reducing destructive dissection work; hence save a lot of time for the process. EIS has also successfully been used to study the mechanism of glass electrode failure and the possibility to resume its performance after exposed to high temperature (Refer to Fig.1). Figure 1