ED Sciences Chimiques
Soft membrane interferometric stress sensor
by Ilyes JALISSE (Centre de Recherche Paul Pascal)
The defense will take place at 14h00 - Amphithéatre CRPP 115 Avenue du Dr Albert Schweitzer, 33600 Pessac
in front of the jury composed of
- Carlos DRUMMOND - Directeur de recherche - CNRS - Directeur de these
- Frédéric NALLET - Professeur des universités - Université de Bordeaux - CoDirecteur de these
- Jean COMTET - Chargé de recherche - ESPCI - Examinateur
- Joshua MCGRAW - Chargé de recherche - ESPCI - Rapporteur
- Antoine CHATEAUMINOIS - Directeur de recherche - ESPCI - Rapporteur
- Cécile ZAKRI - Professeur des universités - Université de Bordeaux - Examinateur
Compliant surfaces play a crucial role in many systems of interest, particularly in the biological domain. To understand the surface properties of gels, such as wettability or adhesion, it is essential to account for long-range deformations. Synovial joints, for instance, exhibit remarkable lubrication properties. However, the mechanisms underlying this performance, which involve charged macromolecules and soft surfaces, remain poorly understood. In this context, we developed a surface stress sensor based on a surface forces apparatus (SFA), enabling precise measurement of the deformation of an elastic membrane through multiple beam interferometry. The membranes used are produced using a robust method and are characterized through electrostatic actuation tests and swelling experiments. First, we analyzed the static response of the membranes under electrostatic actuation. The forces involved demonstrated the capability of our device to measure interaction forces on the order of μN. Subsequently, we studied sphere- membrane interactions in the presence of electrolytes under the application of an alternating electric field. The results revealed the emergence of an attractive force due to the limited electrostatic screening, and a repulsive osmotic force, observable over the long term. Finally, we explored the elastohydrodynamic (EHD) coupling that arises when a solid object moves near an elastic membrane in an aqueous environment. These studies open new perspectives for under- standing interactions between soft, deformable surfaces and their surroundings.