Study of High Functional WO3 Film Sensors for Practical NO2 Detection
Four types of tungsten trioxide (WO3) particles (spherical, disk, cuboid, and hexagonal) were prepared and WO3 thick film sensors were fabricated by dropping suspensions containing the obtained various WO3 powders on Au comb-type microelectrodes. The sensing properties to 0.05-ppm NO2 revealed that a cuboid WO3 film sensor had the best response-recovery characteristics with the 90 % response and 90 % recovery times of 1.3 and 0.9 min at 200 °C, respectively. On the other hand, a hexagonal WO3 film sensor showed extremely high sensor response even to 0.01-ppm NO2 at 200 °C, but the sensor response fluctuated greatly over the operating temperature range from 80 to 300 °C. Practical evaluation of the cuboid WO3 thick film sensor in a roadside atmosphere was carried out and it was demonstrated that the evaluated values for the sensor unit had accuracy and resolution equivalent to CLD (Chemical Luminescence Detection) without any maintenance and calibration for 10 weeks.
Yuan Ming Huang
Z. C. Meng et al., "Study of High Functional WO3 Film Sensors for Practical NO2 Detection", Key Engineering Materials, Vol. 538, pp. 308-311, 2013