Investigation of the electrode surface of a liquid quality sensor by local impedance spectroscopy

Local electrochemical impedance spectroscopy (LEIS) is a suitable technique for the investigation of electrode surfaces. In this paper, we investigate the correlation between changes on the electrode surface with the results of LEIS. For LEIS measurements, a novel measurement set-up is developed with high mechanical stability and a sufficient space resolution of 200nm. Three identical liquid quality sensors were exposed to aging with different immersion time. Using scanning electronic microscopy (SEM), the results depict that the deposits increase with immersion time and have typical dimensions of 0.7 mm2. The LEIS investigation shows a good sensitivity to deposits on electrode surfaces and results are confirmed by the SEM investigation.