La bionique des plantes thigmotropiques

Climbing plants, such as vines, cucumbers, squash, watermelons, and peas, have rod-like, flexible structures called tendrils that enable them to attach to supports through thigmotropism, adopting helical conformations. Our preliminary results indicate that singular snapping-like events can occur in both bioinspired synthetic helices and living tendrils. This serves as proof of concept for our proposal: transitioning from bioinspired to bionic snapping-prone systems : human-conditioned living systems with specifically designed mechanical properties. We will begin by developing a fundamental understanding of instabilities in elastic rods to determine the conditions under which living plant tendrils reach critical snapping-prone conformations. This knowledge will enable us to create a "tendril motor" : a bionic device without frictional articulation (i.e., no pistons or rotating parts) that leverages thigmotropic differential growth to generate rapid mechanical action through snapping.

Cotutelle : This PhD project will take place both in Paris (laboratoire MSC, Université Paris Cité) with Dražen Zanchi (DZ) and in Lyon (ENS de Lyon) with Julien Derr (JD)

DZ: Head of the DOMM team in the MSC laboratory, 30-year-long experience in theoretical and experimental physics, participation and coordination of transversal/interdisciplinary and international actions in biophysics, soft-matter, chemical engineering, food science and pharmacology, since 2020 joins the MSC lab (group Dynamics and Organisation of Soft Matter) from his former affiliation (ENS Paris) to initiate and develop transversal actions focussed on dynamics and mechanics of living and soft matter systems: plant tendrils and related bioinspired devices (grant IDEX UPC “Dynavine” 2021-2022, Labex SEAM UPC « DynaSnap » 2025), bacterial adhesion (collaboration with University of Split, Erasmus Plus grant), microalgae dynamics in foams and near surfaces (CNRS grant ​​Dynamique Plastisphère).

JD is a physicist working on morphogenesis and self-organisation. He is part of the MOSAIC team in the RDP laboratory of ENS Lyon. He works at the interfaces between physics and biology. He has been working on plant motions and growth for over a decade. He has expertise in fine kinematics (including managing 3D projection effects) and mechanics measurements. JD will benefit from plant dedicated infrastructures at RDP including growth chambers and greenhouses. JD will be mostly involved in the experimental part of the project : Design, set-up, kinematics tracking, mechanics measurement, data processing. He will also be involved in tutoring of the PhD student.

We are looking for a candidate with strong background in general physics and mechanics. This PhD work demands also high motivation for performing mechanics experiments. Interest in biological system is a plus. The student is expected to participate in two sets of experiments. The first set will take place at MSC, primarily supervised by DZ on a daily basis and by JD through weekly meetings (mostly via Zoom). These experiments will focus on mechanics, as described above (cf. supra). The second set will be conducted at RDP, with regular supervision by JD and weekly Zoom meetings with DZ. The schedule for these experiments will be organized to minimize unnecessary travel while ensuring efficient progress in the PhD. Details of the experimental work are provided in the project description (cf. infra). The thesis will be equally divided between MSC and RDP (50/50), with DZ and JD contributing equally to its supervision. Twice a year, joint meetings between the MSC and RDP teams will be held alternately in Paris and Lyon. These meetings will provide an opportunity to enhance the PhD’s progress and foster collaboration. In addition to the regular annual thesis committee (CDT) meetings, these gatherings will offer valuable training in oral communication and presentation skills. Furthermore, the student will participate in GDR Phyp meetings and attend at least one international symposium on plant biophysics.This PhD structure will equip the student with the necessary skills and flexibility to work on both the physical (mechanical) and biological aspects of this inherently multidisciplinary topic. The dynamic French plant physics community, particularly around the GDR, will provide an excellent environment for the student to build a strong professional network for the future.