Use of intelligent ceramic materials as a strategy for the development of chemical sensors

Abstract

The practical applications of chemical sensors based on ceramic sensing elements is strongly limited by the problems inherent to their sensing mechanisms. For gas sensors, the main problems of semiconducting oxides are the insufficient gas selectivity, the inability to detect very low gas concentrations, and changes in sensing properties caused by surface contamination. For humidity sensors, the factor which limits the market diffusion of porous ceramics is the progressive drift in sensor resistance, which makes a heat-cleaning treatment of the sensing elements necessary for the recovery of sensor performance. The problems encountered in using the conventional ceramic materials as chemical sensors are strictly related to their sensing mechanisms. Give that, the strategy to eradicate the problems is the exploitation of innovative sensing mechanism. Novel detection principals for chemical sensors can be obtained by materials having intelligent properties. Examples of multiphase systems for humidity and gas sensors are reviewed.