A Biomechanical Characterization of Plant Root Tissues by Dynamic Nanoindentation Technique for Biomimetic Technologies

In this work we present a study on mechanical properties of Zea mays primary roots. In order to have an accurate overview of the root structure, three different regions have been analyzed: the outer wall, the inner part, and the root cap. We used a dynamic nanoindentation technique to measure the elasticity modulus of root tissues in correspondence of different distances from the root tip. A sample holder was built to test the tip and a method conceived to separate the outer wall of the root from the inner part. As determined by dynamic nanoinden‐ tation, we measured the storage modulus of plant roots over 1–200 Hz range. We found that the values of the storage modulus along the outer wall are higher with respect to the central core. Moreover, the inner core and root cap seem to be similar in terms of elasticity modulus. This study aims to shed light on the mechanical properties of roots that significantly affect root movements and penetration capa‐ bilities. The gathered data on mechanical response and adaptive behaviours of natural roots to mechanical stresses will be used as benchmarks for the design of new soft robots that can efficiently move in soil for exploration and rescue tasks.