Figure 5.

(a) Response of the film to changes in CO₂, plotted along with a reference sensor’s CO₂ readings. (b) Fit of two different calibration algorithms to the fluorescence ratio R, plotted as a function of the reference CO₂. $Fit1$ considers a quadratic dependence on CO₂, while $Fit2$ also considers a quadratic dependence on CO₂, but with different coefficients depending on whether R (and hence, CO₂) is increasing or decreasing. (c) Reference and estimated CO₂ from our prototype, obtained with both algorithms.