Thermoelectric micro-multi-gas sensor for the detection of hydrogen, carbon monoxide and methane

Micro-multi-gas sensor (micro-MGS) of 3 thermoelectric devices with 3 different combustion catalysts was developed. Using the micro-heater meanders of Pt/Pt-W thin film, the temperature of the Pt/Al₂O₃, Au/Co₃O₄ and Pt/Al₂O₃ catalysts were controlled to be 360, 240 and 140 °C for the selective combustion of CH₄, CO and H₂, respectively. The gas sensing performance of the micro-TGS for the gas mixture of 0.5-vol.%CH₄ + 0.5-vol%CO + 0.5-vol%H₂ was been investigated. The Pd/Al₂O₃ burned all gases and the Au/Co₃O₄ could burn CO selectively. The Pt/Al₂O₃ burned H₂ and CO by controlling the temperature of the catalyst. The selectivity of this micro-MGS with the Pd/Al₂O₃, Au/Co₃O₄ and Pt/Al₂O₃ catalysts is higher than that of a SnO ₂ based thick-film sensor array for H₂, CO, CH ₄. From the voltage signal from 3 different sensor elements, the micro-MGS could estimate the gas concentration selectively without any gas separation tool.