The aim of this book is to introduce upper level undergraduate and postgraduate chemistry students to the exciting world of chemical sensors. It will also be of inteest to students in the biological and medical sciences and to electronic engineers. The book directs students towards the future and indicates how important chemical sensors will be in the world of micro total analysis systems. The book deals with the different types of chemical sensors and explains the underlying principles behind the way in which they function. It is well illustrated with drawings of the different chemical sensor types. The following sensor types are discussed; electrochemical sensors including both potentiometric and voltammetric sensors, optical sensors with emphasis on their use with optical fibres, calorimetric sensors, solid electrolyte and semiconductor gas sensors, and piezoelectric-based mass sensors including surface atomic wave sensors. Biosensors are a sub-class of chemical sensors and so are described amongst the different chemical sensor types.