PhD position in the physics of embolism propagation in leaves: high-speed imaging and biomimetic microfluidics (M/F)

Job Description

Thesis Subject

During drought, the water columns under tension within plant vessels can rupture, allowing air bubbles to form. These embolisms locally interrupt water transport and may spread through the vascular networks of leaves, contributing to hydraulic dysfunction in the plant. Despite the importance of this phenomenon, the physical mechanisms governing the speed and pathways of embolism propagation remain poorly understood.

This experimental PhD project will pursue two complementary objectives.

The first part will focus on characterising embolism propagation in real leaves. An imaging system combining an ultra-high-speed camera with a slower camera will be developed to detect embolism events, trigger high-speed acquisitions, and measure their dynamics over timescales ranging from several hours down to a few microseconds. The work will include designing and automating the experimental setup, synchronising the cameras, optimising the illumination, and developing image-processing methods to extract propagation pathways and velocities. Several plant species and different branching levels of the vascular network will be investigated. Complementary characterisation using X-ray tomography and environmental scanning electron microscopy may also be carried out on the Institute's characterisation platform to relate the observed dynamics to leaf anatomy.

The second part will focus on developing biomimetic microfluidic devices that reproduce the main hydraulic properties of leaves under controlled conditions. Existing systems greatly simplify the geometry, connectivity, and deformability of real vascular networks. The successful candidate will design and fabricate, mainly in PDMS, reticulate and hierarchical microfluidic networks that reproduce biological leaves with substantially greater fidelity. The influence of network topology, channel and constriction dimensions, deformability, and evaporation fluxes on embolism propagation pathways will be investigated. The devices will be produced using the INPHYNI microfabrication platform, which includes a clean-room facility.

The two approaches will be developed in close interaction. Observations made on real leaves will guide the design of the biomimetic systems, while microfluidic experiments will make it possible to isolate and control the physical mechanisms responsible for embolism propagation. The PhD project therefore aims to establish new connections between fluid mechanics, soft matter physics, microfluidics, and plant hydraulics.

Desired skills and qualifications

The project is intended for a candidate with a background in physics, fluid mechanics, biophysics, engineering science, or a related field, and a strong interest in experimental research.

A high degree of independence will be required to design experiments, identify the most relevant parameters, improve existing setups, and propose new experimental configurations. The successful candidate should demonstrate scientific curiosity, rigour, initiative, and an ability to work in an interdisciplinary environment.

Experience in optics, high-speed imaging, image processing, scientific programming, microfluidics, or microfabrication would be an asset. Theoretical or numerical knowledge of fluid mechanics would also be appreciated.

Your Work Environment

The PhD will be carried out at the Institut de Physique de Nice (INPHYNI), a joint research unit of CNRS and Université Côte d'Azur. INPHYNI is a physics laboratory covering a broad range of research topics, with strong activities in fluid mechanics, soft matter physics, biophysics, microfluidics, and interfacial phenomena.

The project is part of the ERC Starting Grant EMBIOMO, which focuses on the dynamics of embolism propagation within leaf vascular networks and on the development of biomimetic models capable of reproducing these phenomena under controlled conditions.

The successful candidate will join a team of PhD students, postdoctoral researchers, and permanent researchers with both theoretical and experimental backgrounds. Regular scientific meetings will help coordinate the different approaches within the project, compare experimental results with physical models, and promote interactions among team members.

The work will benefit from the Institute's facilities, including an ultra-high-speed camera, imaging and characterisation platforms, and a microfabrication platform comprising a clean-room facility.

The PhD will be conducted in close collaboration with plant biologists and biomechanics researchers at INRAE who specialise in plant hydraulics and plant vulnerability to drought. These collaborations will provide access to biological samples, expertise in plant physiology, and regular discussions to support the interpretation of the results.

INPHYNI offers a rich and stimulating scientific environment, with regular seminars, numerous national and international collaborations, and daily interactions between experimentalists and theorists.

Compensation and benefits

Compensation

2300 € gross monthly

Annual leave and RTT

44 jours

Remote Working practice and compensation

Pratique et indemnisation du TT

Transport

Prise en charge à 75% du coût et forfait mobilité durable jusqu’à 300€

About the offer

About the CNRS

The CNRS is a major player in fundamental research on a global scale. The CNRS is the only French organization active in all scientific fields. Its unique position as a multi-specialist allows it to bring together different disciplines to address the most important challenges of the contemporary world, in connection with the actors of change.

CNRS

The research professions