Scanning gel electrochemical microscopy (SGECM): The potentiometric measurements

SGECM potentiometric measurements are developed with a novel Ag/AgCl-gel micro-reference electrode. The electrode is prepared by electrodeposition of chitosan on Ag micro-disk electrode followed by anodic chlorination of Ag. It is approached to the sample by shear force feedback, and the potential between the electrode and the sample is recorded with a highly sensitive voltammeter. Based on this, simultaneous mapping of topography and electrochemical potential is achieved, with the sample exposed in air. Tests of model samples indicate that the electrode is reliable and stable for potentiometry, and two different metals (Al and Cu) are clearly identified from the topography and potential maps.