Tungsten Oxide Nanowires-Based Ammonia Gas Sensors

The application of tungsten oxide nanowires synthesized by a simple soft-chemistry route in the presence of deferoxamine mesylate (DFOM) for ammonia gas sensing is reported. The crystalline tungsten oxide nanowires are self-assembled into bundles with typical lengths of 200 to 1000 nm and width around 20 nm. For sensing tests, tungsten oxide nanowires suspended in water were deposited onto alumina substrates by drop-coating and subsequently calcined at 500 degrees C in air. The sensors were tested at different temperatures to evaluate the best working conditions for ammonia gas monitoring (1-10 ppm) in terms of sensitivity, selectivity and response time. These sensors have proven to detect ammonia gas with remarkably higher sensitivity than other sensors based on tungsten oxides. The response and recovery times are fast (in the order of 2 min). All in all, these features make these sensors promising candidates for healthcare applications.