An investigation into the effect of fabrication parameter variation on the characteristic of screen-printed thick-film silver/silver chloride reference electrodes

Abstract

Purpose – The purpose of this paper is to show how the fabrication parameters of screen-printed thick-film reference electrodes have been experimentally varied and their effect on device characteristics investigated. Design/methodology/approach – The tested devices were fabricated as screen-printed planar structures consisting of a silver back contact, a silver/ silver chloride interfacial layer and a final salt reservoir layer containing potassium chloride. The fabrication parameters varied included deposition method and thickness, salt concentration and binder type used for the final salt reservoir layer. Characterisation was achieved by monitoring the electrode potentials as a function of time following initial immersion in test fluids in order to ascertain initial hydration times, subsequent electrode drift rates and useful lifetime of the electrodes. Additionally, the effect of fabrication parameter variation on electrode stability and their response time in various test media was also investigated. Findings – Results indicate that, although a trade-off exists between hydration times and drift rate that is dependent on device thickness, the initial salt concentration levels and binder type also have a significant bearing on the practical useful lifetime. Generally speaking, thicker devices take longer to hydrate but have longer useful lifetimes in a given range of chloride environments. However, the electrode stability and response time is also influenced by the type of binder material employed for the final salt reservoir layer. Originality/value – The reported results help to explain better the behaviour of thick-film reference electrodes and contribute towards the optimisation of their design and fabrication for use in solid-state chemical sensors.