Workshop on colloidal transport

Workshop on colloidal transport

Fri, July 10
10:00
Amphi OSUC
Visio

Schedule:

10:00 – Eleonora Secchi (Senior Scientist in the Department of Civil and Environmental Engineering at ETH Zürich). Biofilms as Living Soft Materials: Linking Mechanics, Microstructure, and Function

11:00 – Manouk Abkarian (CNRS Research Director at the Centre de Biologie Structurale in Montpellier)

Blood transport in vascular networks.

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Biofilms as living soft materials: Linking mechanics, microstructure, and function

Eleonora Secchi
 
Biofilms are communities of bacteria embedded in a self-secreted extracellular polymeric matrix. From a physics perspective, they can be viewed as living soft materials: structurally heterogeneous polymer networks whose permeability, mechanical response, and transport properties evolve over time and depend on physicochemical conditions. These coupled mechanical and transport processes are central to biofilm persistence in natural and engineered environments, yet a predictive physical framework linking microstructure, deformation, and transport across scales is still lacking. In this seminar, I will present a polymer-network framework for biofilm mechanics and transport that draws explicit analogies with soft-matter physics, linking network structure to effective permeability and mechanical response. Using microfluidic platforms combined with in situ imaging and modelling, we probe biofilm behaviour under controlled shear and chemical conditions, revealing how flow-induced deformation and biochemical composition feed back on transport, clogging dynamics, and mechanical stability. Together, these results position biofilms as adaptive living materials whose properties are dynamically regulated by their internal structure and mechanical state.
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Enhanced rheological and molecular transport in microcirculatory-scale red cells suspension flows

Manouk Abkarian

 

Blood transport in the microcirculation is controlled by red blood cell (RBC) deformability, hematocrit, and laminar flow. Using complementary microfluidic experiments, we show that RBCs actively enhance both blood flow and molecular transport through nonlinear hydrodynamic interactions. Blood exhibits an adaptive rheology in which network resistance decreases with increasing pressure, following a universal scaling governed by RBC mechanics. RBCs also strongly enhance solute mixing, with maximal transport at physiological hematocrits and under aggregation. This transport is anomalous rather than Brownian and becomes largely independent of molecular size. These results establish RBCs as active regulators of both flow resistance and plasma transport, revealing anomalous (“sticky”) transport as an intrinsic feature of microcirculatory blood flow. Alterations in RBC deformability or aggregation are therefore expected to significantly affect tissue exchange, hemostasis, and drug delivery.