Electrochemical sensor chips for multiple measurements of dissolved oxygen, pH and oxidation-reduction potential in aquacultural farming

Abstract

Dissolved oxygen (DO), pH and oxidation-reduction potential (ORP) are important parameters of water quality in aquacultural farming and these parameters need to be monitored continuously. In this paper we report fabrication and characterisation of electrochemical sensor chips with pairs of platinum (Pt) electrodes and Ag/AgCl electrodes to measure multiple parameters including DO, pH and ORP with low cost and simple operation. The platinum electrodes were fabricated by lithography, sputtering and lift-off techniques. The fabricated platinum electrodes were used as working and counter electrodes and a silver/silver chloride (Ag/AgCl) was used as a reference electrode. To measure DO, cyclic voltammetry (CV) measurements were performed when the platinum electrodes were dipped in pH buffer solutions as DO levels ranged from 1.5 to 26 ppm. The CV results showed the increase in current related to the reduction peak of oxygen when DO concentration increased. The correlation of the current and DO levels was also determined. The ORP of various electrolyte solutions which have different pH and ORP values was determined by open circuit potential (OCP) measurements. The correlation of OCP values, pH and ORP values was investigated. The stability of ORP values and durability of the fabricated electrodes were also studied. The results exhibited the possibility of using the fabricated electrode chips for multiple measurements of DO, pH and ORP in aquacultural farming.