Development of chemical sensors for ions in plating solutions

Chemical sensors based on electrochemical principles and fabricated by the microelectronic thick film metallization technique are developed for the detection of ions in plating solutions. The advantage of this approach is that small, reliable, fast-responding sensors can be developed by placing the sensing elements, working, counter and reference electrodes on a single, small-sized substrate. The arrangement of multiple square working electrode elements in an array enhances sensor response time and sensitivity. However, interactions among the electrode elements must be taken into consideration. This paper describes the results of analyzing these interactions based on a mathematical model. The anticipated responses of these sensors at very short and very long times, based on the model, are predicted and experimentally verified. Specifically, the performance of a sensor using an array of square working electrode elements for sensing ferric ions in a Zn-Fe simulated plating bath was carried out.