BioElectronic Tongues: When the Sensor Array Incorporates Biosensors

One of the recent advances in the design of electronic tongues has been the incorporation of biosensors in order to tackle new application fields or to improve the existing ones. These bioelectronic tongues, as they have been named, are only distinguished from the conventional ones in the incorporation of one or several biosensors into the sensor array, normally sharing the same transduction principle to facilitate its compatibility. After reviewing existing examples from the literature, this chapter will deepen in two case studies, one with potentiometric sensors and the other with devices of the voltammetric type. The first is designed having in mind the monitoring of the haemodialysis process, wherein urea and creatinine biosensors constructed on the basis of the proper enzymes and ammonium ion selective electrodes are complementedwith additional sensors for alkaline ions. The second case, aimed to the detection of phenolic antioxidant compounds, uses an array of voltammetric biosensors incorporating different phenol-oxidizing enzymes to generate the cross-sensitive responses. In both cases, the data processing tool used has been artificial neural networks, able to provide a precise response model to estimate concentrations of involved species.