The linear discrimination analysis (LDA) was done in Origin 2019, where all individual barcode response patterns were used as training data and the levodopa concentration as groups. The best performing single sensor regarding the total classification error was selected as sensor 1 and the classification matrix was plotted in a heatmap. Based on sensor 1, the best next combination of two sensors was selected. This was repeated for three sensors. With all four sensors of the barcode included, we again plotted the classification matrix.