Biomechanical Characterization of Hook-Climber Stems for Soft Robotic Applications

Plants are getting increasing interest from scientists for the development of novel biomimetic products. Especially, the stems of climbing plants possess impressively high-adaptable materials, which can be relevant in robotics for the development of new machines able to work in unpredictable environments. In this work, we present a study on the mechanical properties of the stem of the hook-climber Galium aparine. Three different stem regions (basal, middle and apical parts) were analyzed in order to investigate how the mechanical properties vary along the stem. Tensile tests were performed on the different stem parts. Results demonstrated a significant decrease of Young's modulus, the breaking strain and the tensile strength values from the basal to the upper parts. In contrast, we observed a decrease only in the tensile strength between the middle and apical parts. The collected data on the mechanical response of natural plant stems will be used as benchmarks for the design of novel soft robots that can act and move in real unstructured scenarios for exploration and monitoring tasks.