Gas sensors based on oxygen plasma functionalised MWCNTs and plasma-treated nanotubes decorated either with gold nanoclusters or tin oxide nanoparticles were evaluated for the detection of NO_2, CO and ethylene. The sensor active layers were deposited by airbrushing onto micro-machined silicon transducers. Sensitivity, linearity, selectivity, response and recovery times and humidity effect were studied. XPS and TEM were employed to analyse the gas sensitive films. Among the different sensors tested, those based on tin oxide decorated MWCNTs showed the highest sensitivity to NO_2 (at ppb level) and the lowest humidity cross-sensitivity when operated at room temperature.
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