Chapter 4 Ion sensors with conducting polymers as ion-to-electron transducers

Potentiometric ion sensors, or ion-selective electrodes (ISEs), are one of the oldest and most successful electrochemical sensors with a large number of applications, especially in clinical analysis. The analytical performance of solid-state ion sensors with conducting polymers as ion-to-electron transducer (solid-contact ISEs) has been significantly improved over the past few years. Of particular interest is the large improvement of the detection limit of such solid-contact ISEs down to the nanomolar level. Solid-state ion sensors with conducting polymers as sensing membranes are useful in some applications, particular importance are the pH sensors based on polyaniline that can be also applied in non-aqueous solutions. Polypyrrole-based sensors for nitrate also show great promise for water analysis. However, in addition to these two excellent examples, a large number of functionalized conducting polymers have been synthesized already, and these materials may offer unique possibilities for fabrication of durable, miniaturized ion sensors.