Solid state gas sensor for fast carbon dioxide detection

Some promising results on the behaviour of BaTiO3-CuO sputtered thin films under carbon dioxide atmospheres are presented. The sensing material response to different CO2 concentrations is due to a reversible reaction based on the presence of BaCO3 in the material. The measurement of impedance changes allows monitoring the variation in CO2 concentration. Resistance and capacitance variations are closely related to work function changes in the p-n heterojunction between BaTiO3 and CuO. The frequency response shows spatial-charge and relaxation phenomena that permit finding an optimal working frequency range. The sensing layer thickness influence in the response is reported and also the influence of Ag as additive in the film.