Fabrication of thin-film WO3 sensors and their sensing properties to dilute NO2

We tried to fabricate WO
₃
thin-film sensors using four kinds of WO
₃
particles with very different crystalline morphologies (spherical, disk, cuboid, and hexagonal). Using highly dispersive suspensions prepared, WO
₃
thin films of 1.5-3.0 μm in mean thickness were obtained by micro-injecting film formation method. NO
₂
sensing properties of these thin-film sensors suggested that the sensitivity to NO
₂
as well as the rate of response-recovery depended markedly on morphology and microstructure of the WO
₃
crystals contained.