Study of the evolution in space and time of water diffusion in a leaf through a sub-terahertz portable imaging system

Among the non-destructive techniques capable of obtaining information on biological systems even in vivo, terahertz-based techniques are emerging due to their specificity to the water content, which can represent an important indicator of the presence of microorganisms and, in general, of the health status, particularly in plants. Nevertheless, the analysis of the extracted data (especially for images) and the exploitation of the potential of the technique for the study of the complex phenomena that occur in living tissues are still almost unexplored fields. In this work, the hydration status of leaves both in vivo and ex vivo was monitored continuously and non-destructively by acquiring videos in the sub-terahertz range through a portable imaging system. A model for describing the water flow in space and time in the midvein of a leaf is obtained which is suitable for the analysis of the data extracted from the portable sub-terahertz imaging system. These results show that terahertz-based technology can be used to study biological phenomena even in vivo; moreover, they pave the way for the introduction of a general method for the analysis of terahertz data based on surface fits in space and in time as well.