ISFET electronic tongue system for environmental multi-ion sensing with independent component analysis signal processing

Abstract

In this paper, we present the design of electronic tongue system for multi-ion sensing applications. The ion-sensitive field-effect transistor (ISFET) detects the concentration of a particular ion in aqueous solution. However, when the given chemical solution contains two or more ions, the ISFET sensor can only provide the combined concentration of ions. In this end, our electronic tongue included a blind source separation (BSS) method of independent component analysis (ICA) to process the ISFET signals and to extract the concentrations of individual ions in the solution. The results of ISFET modeling based on fixed interference method (FIM) serve as a priori knowledge to help solve this blind source problem. Experiments are conducted on this electronic tongue system using aqueous solution containing hydrogen and sodium ions flowing through the array of dual H+ ISFET devices. The results of ICA processing successfully determined the concentration of hydrogen ions amidst the presence of sodium ions. This capability of ion separation allows us to move towards the development of smart electronic tongue systems for environmental and water quality monitoring.