Abstract
Thick-film (TF) fabricated chemical sensor arrays have been extensively evaluated both under laboratory conditions and in on-line applications in various industrial processes. A comparison of device performance between these two extremes of environment is presented with particular reference to the sensor lifetimes and their ability to withstand fouling and scaling in the industrial processes to which they are applied. The TF sensors evaluated included those for the measurement of pH, dissolved-oxygen concentration, temperature, conductivity and redox potential. The industrial process environments in which the sensors were studied included closed-loop water re-use systems in power stations, a paper mill and an application involving the pH monitoring of printing ink.