Metal oxide sensors are widely used for chemical species detection. They are based on the electric conductivity variation measurement of a thin semiconductor layer subjected to the target gas exposure. It has been proved that the conductivity variation is linked to a modification of the refractive index of the material. This work deals with the study of a new type of gas sensor based on the measurement of refractive index variations of a sensitive film. Sensitive materials for specific gas detection (butane and ozone) have been identified in the literature. They have been deposited and characterised by various methods to enhance their optical and morphological properties for an optimal gas sensitivity. Sensitivity and selectivity to other gases as function of gas concentration and working temperature have been studied. Integration of optical elements has lead to the realisation of an industrial demonstrator.
