A semiconductor type gas sensor for automobile ventilation control has been developed. A couple of tin dioxide based sensing materials, which were respectively sensitive to gasoline and diesel exhaust gases, were mounted on an alumina substrate with an integrated heater by using screen-printing technique. The sensor's sensing element for diesel exhaust, which was heated at about 300 degreesC, showed high sensitivity to NO2 (>0.5 ppm). The 63% response time to 1 ppm NO2 was approximately 12 s so that the sensor could rapidly detect diesel exhaust. Moreover, the sensor was selective to NO2 against coexisting gases such as CO or hydrocarbons. The sensor's sensing material for gasoline exhaust also showed excellent sensing characteristics to gases in gasoline exhaust. By mounting two materials on a 2.0 mm x 2.6 mm substrate, power consumption of the dual sensor could be reduced to about 360 mW also the sensor could be downsized. The sensor has high potential for air quality control in automobile cabins. (C) 2001 Elsevier Science B.V. All rights reserved.
