Components of all-solid-state ion-selective electrodes

An electrochemical sensor is a qualitative and quantitative device that converts a chemical signal to a measurable electrical signal (Yogeswaran and Shen-Ming 2008). Electrochemical sensors can be divided into three classes: potentiometric, amperometric, and conductometric (Stradiotto et al. 2003). A potentiometric sensor measures an electrical potential when no current is present, while an amperometric sensor produces current when a potential is applied between two electrodes. A conductometric sensor assesses conductivity by measuring the electrical resistance of a sample solution. Ion-selective electrodes (ISEs) are potentiometric ion sensors and a subgroup of electrochemical sensors; they are widely used in various fields of biomedical, environmental, and chemical analysis, and physiological sensing (Bobacka et al. 2003; Bakker et al. 2008; Hu et al. 2016). ISEs are classified into three groups, depending on the nature of the membrane material: glass, polymeric or liquid, and crystal or solid (Fig. 16.1) (Faridbod et al. 2007)