Solid state gas sensor for fast carbon dioxide detection

Promising results on the behaviour of BaTiO3–CuO sputtered thin films as a sensing material under carbon dioxide atmospheres are presented. The response to carbon dioxide of BaTiO3–CuO is due to a reversible reaction based on the presence of BaCO3 in the material. The measurement of impedance changes allows to monitor the variation in CO2 concentration. Resistance and capacitance changes are closely related to work function changes in the p–n heterojunction between BaTiO3 and CuO. The sensing layer thickness influence on the response and the influence of Ag as an additive in the film are also reported.