General information
Offer title : Postoc (M/F) Forces exerted by swelling granular media using seeds and hydrogel beads (H/F)
Reference : UMR5588-PHIMAR-007
Number of position : 1
Workplace : ST MARTIN D HERES
Date of publication : 29 August 2025
Type of Contract : Researcher in FTC
Contract Period : 22 months
Expected date of employment : 1 November 2025
Proportion of work : Full Time
Remuneration : 3000 to 3400 euros gross/month
Desired level of education : Doctorate
Experience required : Indifferent
Section(s) CN : 01 - Interactions, particles, nuclei, from laboratory to cosmos
Missions
Plants do not possess a heart to drive the circulations of their internal fluids, but rely on two mechanisms: osmotic pressure and evaporation. These two mechanisms are actively regulated by either the production of solutes or the opening of evaporation sites, respectively. The osmotic effects lead to high turgor pressures, that are responsible for maintaining the shape of non-lignified plants. Here we are interested in a specific aspect linked to water transport: the rehydration of dessicated seeds. Under water seeds attract water through osmotic effects leading in a strong volume increase and possibly strong pressures. Plants seeds act as elements of peculiar type of granular media, not really studied in literature: swelling granular media.
Activities
The main objective of the post-doc is to understand the physics of imbibition of these granular media. First we will tackle the temporal dynamics of imbibition of single seeds/grains in water, using seeds as chickpeas because of their near spherical shapes. Histological sections will be performed to understand which cells are swelling. Second we will measure the forces exerted by grains when they are hydrated confined in spaces, such as in between two planes, in a tube or within a chamber. Third we will generalize this findings with different types of plant seeds or artificial hydrogel materials. Finally, we aim at using this granular media as an autonomous media to exert pressures by sole imbibition reproducing the phenomenon of turgor pressure.
Skills
The postdoc is mainly experimental but involves theoretical modelling. Appreciated skills: fluid physics, soft matter, biophysics
Work Context
Laboratoire Interdisciplinaire de Physique is located on the Grenoble campus, France. The student will work in a team with Philippe Marmottant (physics of plants) as Internship advisor, together with Catherine Quilliet (modelling), Olivier Stephan (3D manufacturing, hydrogels) and Pierre Recho (theory of porous media).
The position is located in a sector under the protection of scientific and technical potential (PPST), and therefore requires, in accordance with the regulations, that your arrival is authorized by the competent authority of the MESR.
Constraints and risks
No particuliar risk