A NEW PLANAR DEVICE BASED ON SEEBECK EFFECT FOR GAS-SENSING APPLICATIONS

A new planar sensor structure has been developed, which takes advantag e of the differential temperature appearing between the two halves of a tin or an indium oxide film, one half of which is covered with a cat alyst, in the presence of a combustible gas. Since the rates of reacti on of the combustible gas on the two halves of the film are expected t o be different, different amounts of heat are delivered at the two hal ves of the film, resulting in a temperature gradient across the film. According to the Seebeck effect, this temperature gradient produces a voltage difference at the two edges of the film. Different Seebeck vol tage values have been recorded when the structure is exposed to variou s gases, due to the different heat of adsorption or combustion deliver ed from each gas at the two portions of the film.