A Potassium-sensitive Micro/Sub-micro-electrode for Shear Force-based Scanning Electrochemical Microscopy

Abstract

A micro/sub-micrometer-sized potassium-sensitive electrode was fabricated and used as a probe for shear force-based scanning electrochemical microscopy (SECM) in standing approach mode, and the pores of a membrane filter were imaged as a model of living cells. In general, the electrode was prepared by silanizing the walls of a capillary with octadecyltriethoxysilane (ODS) to prevent penetration of aqueous solution into the capillary, and then filling with a solution of an ionophore. When this electrode approached the surface, the ionophore solution slightly protruded from the tip and contacted the sample surface. Therefore, the hydrophobic layer, at the tip of the capillary only, was removed. Because of this treatment, a very small amount of the aqueous solution penetrated the tip of the capillary when the electrode was immersed in aqueous solution. Using this capillary, SECM and topographic images of a polycarbonate membrane filter having 5 m pores were successfully obtained.