Fig. 5: Tomographic chemical imaging of living tomato plants undergoing drought stress.

A Water content of soil (Data are means ± SD from four individual samples). At day 1, regular watering was halted causing a decay in soil water content over 6 days. B–D Stress markers of including flavonoid absorption (B) did not show difference during the 6 days (n = 7). And NBI (C) show deflections starting on day 6, confirming the induction of a water stress state (n = 7). Data are means ± SD from seven individual leaf tests. Photographic evidence (D) also corroborates the water stress state at day 6 with slightly yellowing. E The sensing COF microneedle interface is imaged in the tomato leaf midrib stained with toluidine blue showing before (top) and after (down) injection at the abaxial side. The blue circle indicates the vasculature zone and dashed red triangle indicates the point of microneedle injection. Images are representative of three independent experiments. F Data collection from the TSMN700 sensor injected into the midrib of a tomato leaf was from a smartphone camera at periodic time points after day 1. G pH of vascular saps measured by inner circle color difference against outer circle for TSNM700 injected into the midrib of tomato leaves at different time points, after day 1. Data are means ± SD from four individual leaf tests. H In-Vivo chemical tomographic images in the form of depth-orientational angle pH maps. I Alternative depiction of maps onto the 3D conical profile of the COF microneedle sensor interface. In B, C, and G data are shown as boxplots of the number of indicated samples displaying the maximum and minimum, first and third quantiles, and the median. In B, C, and G data are analyzed by one-way ANOVA followed by the Tukey test and the P values were shown. Source data are provided as a Source Data file.