Séminaire PMMH – Martin Brandenbourger (IRPHÉ, Marseille)

Vendredi 11 octobre de 11h00 à 12h00 - Salle réunion PMMH 1

Towards models of fluid transport in active vascular networks

Liquid flows in vascular networks are among the most effective ways to transport matter and
information for life. From animals to fungi, the most adaptable organisms utilize vascular
networks with vessels that actively contract upon local sensing of stimuli instead of central
pumping mechanisms. These self-contractions bring unique autonomous functionalities such
as adaptative locomotion and resilient immunity defense.
To finely control fluid flows in these networks and properly deliver matter and information, living organisms combine both passive and active interactions. One striking example is the lymphatic
system in which interstitial fluids are transported across the whole body of mammals against
intricate changes of pressures. In the collecting lymphatics, lymph is transported via active
vessel contractions combined with passive leaflets that ensure unidirectional transport. The
nature of the active contractions, the multi-scale and multi-physics of the system make it
challenging to model.
In the first part of this seminar, I will describe how the development of artificial models inspired by the lymphatic system enables systematical studies on the role of leaflets and channel
contractions. In the second part of this seminar, I will present the first steps toward the
development of robotic matter capable of mimicking active self-actuations observed in nature.
Model experiments combining passive elasticity and local active forces are used to develop
models predicting the mechanical properties of such active materials and demonstrate how
the interplay between dissipation, restoring forces and active forces controls their dynamics.
These results open the way to a better understanding of fluid transport in self-contracting
networks and the reproduction of living matter functionalities in artificial systems.

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