Figure 6

(a) Response of the as-deposited sensor in terms of the first (\(a_{PC1}\), green) and second. (\(a_{PC2}\), red) principal components measured at different conditions and (b) a corresponding diagram of \(a_{PC1}\) vs. \(a_{PC2}\). Responses to wet air (blue) with 30% RH, to heating up to 60 °C (pink), to both humidity and heating simultaneously (magenta), and to 1000 ppm of hydrogen in dry air at room temperature (orange) are shown.