Acoustic wave-based NO2 sensor: Ink-jet printed active layer

Microsphere-templated BaCO3 films with well-defined area were deposited onto quartz crystal microbalances by thermal ink-jet printing, and the devices were characterized with respect to their microstructures and NO2 sensing characteristics. Highly porous three-dimensional BaCO3 frameworks with promising sensor characteristics were obtained. The printed thin films exhibited reversible frequency shifts following exposure to NO2 and subsequent recovery under CO/CO2 at 400 °C. The feasibility of controlled deposition of complex functional films in controlled patterns is discussed in the context of the direct-write features of ink-jet printing.