A Catalytic Sensor using MEMS process for Methane Detection in Mines

Detection of methane is a vital aspect of environment security in coal mining. At present, catalytic sensors are widely used. A new structure sensor of methane gas had been designed and fabricated. The Pt resistance for temperature and heater is on the silicon membrane with micro air bridge structure. The sensor has advantages of simple structure, easy processing and high accuracy compared to normal sensors. The sensitive element is a platinum temperature sensor that measures the heat of combustion liberated as the combustible analyte is oxidized on its catalytic surface covered with a layer of doped porous alumina. Sputtering technique, lithography and so on are mainly adopted to fabricate the element´s Pt film heating resistance. The fabrication of the heating resistance is a crucial step in this experiment. The heating resistances are completed under all- same technique. So the heating resistances´ value will be in good concordance. Methane generally needs high temperature to support its normal work. To meet this temperature region, the element´s power consumption will be high if the element´s body resistance is big. In order to decrease the element´s power consumption, it is necessary to decrease the body resistance. As the traditional sensitive element, to get high sensitivity, it is necessary to put some catalyst into the sensitive film material as PdCl₂. Because of micro-fabrication (MEMS) techniques, catalytic sensors are likely to be smaller and more lower power consumption.