A chemical sensor is composed of one part supplying chemical recognition coupled to one transducing system. At the recognition origin, interaction with the target chemical species is of two types, either electronic exchange, or ionic exchange. Two large classes of materials that can supply recognition proceed: metals and semiconductors giving rise to electronic exchange and ionic conducting materials giving rise to ionic exchange. This paper is structured in two large parts, emphasizing on materials inducing specific interactions: - semiconductor materials (metallic oxides and molecular semiconductors) and - ionic conductor materials. In each part will be presented nature of materials, way of elaboration, mechanisms of interaction with target chemical species and associated response laws, applications and new developments.
