Improved stability at the polymeric membrane/solid-contact interface of solid-state potentiometric ion sensors

Solid-state ion sensors have been developed in which permselective polymeric membranes are cast on solid electrode surfaces with no internal electrolyte solution. While solid electrode contacts lead to simple, flexible fabrication processes, sensors of this type have had the serious drawback of drifting over time. In the present study, it was found that adding silicon tetrachloride adhesion promoter to polyurethane-based ion-selective membranes cast over silver epoxy solid electrode contacts significantly improved the potentiometric stability of the resulting solid-state potassium-selective sensors. The increased stability is thought to be the result of a better-defined interfacial potential between the sensing membrane and the solid electrode contact. This is attributed to better membrane adhesion to the electrode and to the formation of a silver chloride layer on the surface of the solid contact.<>