Tungsten Trioxide Films for Detection of Nitrogen Oxide in Automotive Exhaust Streams

40950 November 19, 1996 Sensor Research and Development Corporation Since nitrogen oxide (NOx) emissions from motor vehicles account for about half of all NOx fossil fuel combustion emissions, small, low-power, inexpensive, and accurate sensors are required to monitor these emissions. This project will determine the feasibility of using carefully prepared metal oxide films to provide a small, low-power, inexpensive and accurate means to measure NOx concentrations with high reliability and repeatability. Conductivity measurements will be made of doped and undoped tungsten oxide (WO3) films exposed to known concentrations of NO and NO2 at a variety of temperatures, in a variety of oxygen concentrations, and in the presence of several interferant gases. Conclusions will be drawn as to the optimum temperature(s) at which each film should be operated to attain maximum sensitivity and selectivity, what role oxygen plays in the sensor response, and how selective the films are to NOx compared to other combustion exhaust gases. Phase II efforts will focus on the development of a compact, rugged, inexpensive, commercially viable sensor to make in situ measurements of NOx concentrations in automotive exhaust streams. Anticipated Results/Potential Commercial Applications as described by the awardee: This project should result in a new generation of highly sensitive, highly selective, low cost and portable sensors with numerous immediate and long term applications within the federal government, automotive industry and other private sectors.