| Nano-scale tungsten trioxide particles have been synthesized by the flame spray pyrolysis method and a 3x3 mm2 sensor was made by the drop-coating method using the nanoparticles as the active element. After heat-treatment at 500 °C, the materials structure and morphology were characterized by X-ray diffraction, transmission electron microscopy and Raman spectroscopy. Sensing tests were carried out at 200 and 350 °C respectively, down to a trace nitric oxide concentration of 100 parts per billion. The sensor sensitivity was remarkable at these two working conditions employed in this work, providing evidence for the importance of flame spray pyrolysis method as a scalable sensor materials processing technique. |
