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 deposition and silicon micromachining techniques. This device is realized on the principle of the conventional catalytic gas sensor known under the 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 element and the reference element are integrated together on the same chip 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 400-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.