As far as the particles of the microspray contain

However, an exposure of the Cr-doped TiO2 NTs sensor to CO plus NO2 gas mixture (e.g. 50 ppm CO and 50 ppm NO2) yields almost no difference in the total sensitivity (R0/Rg), resulting in a sensor response at the same direction as that obtained with the NO2 single gas exposure. In the case of un-doped TiO2-NT layer, however, the sensor response with CO plus NO2 gas mixture occurs at the same direction as that with CO single gas exposure (see Fig.