Discrimination Effects in Zeolite Modified Metal Oxide Semiconductor Gas Sensors

The use of zeolites to enhance the response and discriminating power of solid state metal oxide semiconductor gas sensors is demonstrated. Thick film sensors were prepared by screen printing layers of chromium titanium oxide (CTO) or tungsten trioxide with various zeolites as over-layers. The sensors gas response was tested against two similar gases; ethanol and isopropyl alcohol. The modified sensors effectively discriminated between the two gases. An understanding of this discriminating behavior is elucidated through computer modeling of diffusion and reaction processes occurring in the zeolite transformation layer and sensor element. Our analysis suggests that the discrimination is the result of the size and shape selective behavior.