GAS SENSOR

PROBLEM TO BE SOLVED: To provide an inexpensive gas sensor, capable of being used at low temperatures and preventing elements from freezing and forming dew, without having to separately provide a heating means. SOLUTION: The gas sensor is provided with both a catalyst layer, in which an exothermic reaction or an endothermic reaction is caused by the presence of a sensing target gas and a thermistor, arranged at a location to which temperature changes are transmitted in the catalyst layer. Heat generation or heat absorption in the catalyst layer is sensed as the changes in the resistance of the thermistor. By using a resistor indicating large changes in a resistance value in the vicinity of, for example, 0°C or room temperatures as the thermistor, it is possible to sense at low temperatures. By passing an appropriate current through the thermistor and heating the thermistor, the resistor, freezing, dew formation, the adhesion of impurities, etc. in element surfaces are prevented. COPYRIGHT: (C)2005,JPO&NCIPI