Spatio-temporal dynamics of microvascular networks

This project propose to investigate the spatio-temporal dynamics of suspension flows in microfluidic networks with a focus on blood flows in model networks of capillaries. In these situations, the coupling between the local rheology and phase separation at bifurcations is known to lead to heterogeneities of the particle (red blood cell) concentration in the network. Theoretical predictions reveal the possibility of multiple solutions and oscillatory states for the distribution of particle concentrations and flow velocities in the different branches.

In collaboration with theoreticians (Olin College and Babson College, MA, USA), and following preliminary experiments, a systematic experimental investigation of the flow of red blood cell suspensions in simple, symmetric networks that have proven to be prone to multistability and symmetry breaking will be carried out. Carefully designed microfluidic systems will allow to explore the conditions leading to multiple flow configurations or oscillatory dynamical states in networks, especially through controlled perturbations of the system to assess the stability of the solutions and trigger transitions between multiple metastable states of the system.

Besides network geometry and flow conditions, blood composition and properties are essential parameters influencing rheology and red blood cell distribution at bifurcations, which in turn govern the global spatio-temporal dynamics of the network. Aggregation properties of red blood cells are such a parameter, that is affected by several pathologies. In line with previous studies highlighting their impact on the structuring of the suspension and its separation at bifurcations, the objective is to carefully examine their impact on the flow patterns. The identification of the conditions leading to heterogeneities, multistability and fluctuations in microvascular networks as well as their characteristics (amplitude, stability, frequency) will contribute to the understanding of passive regulation and stability of microvascular blood flow and associated disorders.