A LOW-POWER INTEGRATED CATALYTIC GAS SENSOR

A new integrated catalytic gas sensor for detecting flammable gases or flammable vapours has been fabricated on silicon with thin film depos ition and silicon micromachining techniques. This device is realized o n the principle of the conventional catalytic gas sensor known under t he name of 'Pellistor'. The detection principle of this gas sensor is based on the measurement of heat emitted by the combustion of the gas with atmospheric oxygen on a small catalytic surface. The sensitive el ement and the reference element are integrated together on the same ch ip of size 2.84 X 2.46 mm2. This double structure requires a very low electrical power of typically 100 mW at an operating temperature of 40 0-degrees-C. The excellent thermal insulation is realized by a 0.6 mum thin silicon nitride membrane. The sensitivity of the sensor is about 13 mV/% methane in air.