Flow and rheology of hydrogels for 3D bioprinting

Context

Extrusion bioprinting uses cell-laden hydrogels to 3D-print tissue-like structures (Fig. 1-A, 1-B). For successful printing, these hydrogels must exhibit self-healing properties: they should yield under extrusion stress and rapidly recover to retain the printed shape. Self-healing behavior is typically assessed by measuring the hydrogel’s storage modulus (G’) under alternating low and high oscillatory stress (Fig. 1-C). In these tests, the gel usually "breaks" at high stress and "heals" at low stress.

However, our recent findings suggest that these methods may not always distinguish between true gel breaking and slippage at the gel/substrate interface. This internship aims to decouple the roles of gel/substrate interactions (i.e. slippage, friction) and bulk rheological properties (i.e. viscoelasticity) on gel flow, in both rheometric configurations (plate-plate geometry) and capillary flow (pressure-driven).

The student will develop and use techniques combining controlled mechanical solicitations and optical visualization to study:

• The deformation field within the gel and at the gel/substrate interface.
• The distinction between gel rupture and slippage under stress, using rheometric measurements and advanced microscopic imaging.
   

Methods

• Rheometry
• Advanced optical microscopy to visualize local deformations and flow fields

Supervision

The internship will primarily take place at the Laboratoire Rhéologie et Procédés (LRP, Grenoble), a joint CNRS/UGA research unit. The LRP is renowned for its expertise in rheology, fluid mechanics, and advanced imaging (LRP website). The project will be conducted in close collaboration with CERMAV (CNRS), a leading laboratory in glycochemistry and biosourced materials (CERMAV website).
 

Candidate Profile

• Level: M1 or M2 student in mechanical engineering, soft matter physics, or materials science.
• Skills: Strong interest in experimental research and data analysis. Experience in rheology, microscopy, or fluid mechanics is a plus.
• Qualities: Rigor, curiosity, and ability to work in a multidisciplinary team.
   

Practical Details

• Duration: 3 to 6 months (flexible start date, ideally from March 2026).
• Compensation: According to French legislation for internship remuneration.
• Location: Laboratoire Rhéologie et Procédés (LRP), Grenoble, France.
• Supervisors: Clément de Loubens (LRP), Hugues Bodiguel (LRP) and Raphaël Michel (CERMAV).