Anisotropic Mechanics of Active Tissues

Close mentoring: daily lab presence of your supervisor, a weekly one-to-one meeting and lab
meetings.

Hands on technical training: biomaterials, organ-on-chip engineering, live imaging, quanti-
tative image analysis, active-matter physics.

A funded PhD opportunity.

A welcoming team: a interdisciplinary environment within a well-equipped biophysics group
with close links to the soft-matter and active-rheology experts of ILM.
 

Collaborations: national and international.

This project aims to study the role of activity and anisotropy in the mechanics of cellular monolayers. Activity is found in systems which are out-of-equilibrium. They consume energy at the microscopic level, such as ATP hydrolysis in cells, which allows them to generate active stresses, such as contractile forces in the acto-myosin network in cells. Anisotropy is found in systems which have elongated particles, or cells, leading to different properties along the X or Y direction. Traditional mechanical characterization of biological tissues considers them as passive and isotropic materials. This project will close this gap using a novel in vitro system: the microstretcher.

The microstretcher is a microfluidic system which allows the application of tension at the tissue scale while manipulating the cellular activity and anisotropy (Dessalles et al., Nature Physics 2025). It is composed of a cellular monolayer, such as endothelial or epithelial cells, lining the surface of a cylindrical channel inside a soft hydrogel Dessalles et al., Biofabrication 2021). When the fluid pressure is increased in the lumen, the diameter of the cylinder increases and the cells are placed under tension.

To that end, you will perform the first long-term rheology tests of curved epithelial (MDCK, MCF-10A) and endothelial (HUVEC) monolayers, and connect their mechanical response to their orientational order. You will:

• Culture cell monolayers in hydrogel microchannels and run the microstretcher.
• Tune the initial nematic order of the tissue.
• Image the tissue live and quantify lumen deformation, cell shape and actin orientation fields, including topological defects.
• Probe the biological origin of the response with pharmacological inhibitors and immunostaining.

Required: M2 student (or equivalent) in physics, biophysics, mechanics, soft matter, bioengi-
neering or a related field; curiosity for living systems; enjoyment of experimental work.

Appreciated: cell culture, microfluidics or microfabrication (PDMS, hydrogels), fluorescence
microscopy, image analysis and data processing (Python), notions of continuum mechanics, rhe-
ology or liquid crystals. We will train you.

Soft skills: rigour, dexterity, patience with long experiments, troubleshooting skills, autonomy,
curiosity for interdisciplinary work at the physics–biology interface.

Working language: English (French not required); international students are welcome.

Not ticking every box? Please apply anyway. Motivation and willingness to learn across
physics and biology matter most. We welcome applications from all backgrounds and are com-
mitted to equal opportunities.