NASICON type ionic conductors for alkali ion sensing

Abstract

Abstract. NASICON type ionic conductors can be used as the sensitive membrane of alkali ion sensors. The main advantages compared to the classical glass electrodes are the better selectivity and lower impedance. The mechanism of response of this type of ionic sensors is presented. The sensitivity results from a direct ionic exchange between the ceramic electrolyte and the solution which has been characterized by impedance spectroscopy. The origin of the selectivity in the NASICON framework is discussed in terms of structural and ionic exchange properties. The performance characteristics of sodium and lithium ion sensing devices are presented. Examples of biomedical applications such as the measurement of sodium concentration in the crevicular fluid and the determination of lithium in artificial serum are described.