Break up of red blood cell aggregates in model 3-D microfluidic channels as well as physiologically shaped channels

The blood flow dynamics through the micro-vascular system, which is the end of our vascular system, depend on many factors, such as the exact shape of the vessels and the aggregation and deformation of the red blood cells (RBCs) [1]. The effects of these parameters have been systematically studied in microfluidics, always using 2D channels with rectangular cross section. It has been shown, for example, that RBCs are not equally distributed between the main vessel and the daughter vessels. The main drawback of this approach is that the micro-channels are inherently different from the physiological vessels, not only because the channels are rectangular, but also because they are confined to 2D. The goal of this research project is to understand the interplay between aggregation, deformation and flow in model 3-D microfluidic channels as well as physiologically relevant shaped channels. The breakup of red blood cell aggregates as well as red blood cell dynamics will be studied by systematically varying the interaction strength between the red blood cells and the complexity of flow geometries. To this end, we will make use of a novel technique, Selective Laser-induced Etching (SLE), to produce 3D structures in glass, while the RBCs will be imaged using ultra-fast confocal microscopy. SLE allows the design of bifurcations into different planes with any desirable shape [2]. Figure 1 indicates one of the final designs of the microfluidic device. To study the shape memory of the vessels the second generation of the bifurcation has been implemented with a parallel and perpendicular orientation relative to the first bifurcation. In a later stage, sequences of the microvascular system will be imprinted from high-resolution 3D reconstructions of human brain histological tissue sections produced in the INM-1 at Forschungszentrum Jülich [3]. Having established flow through healthy structures, we can then also access pathological structures such as aneurisms. References [1] R. Mehri, C. Mavriplis, and M. Fenech, PLoS One, 13 2018, e0199911. [2] M. Hermans, J. Gottmann, and F. Riedel, JLMN, 9 2014, 126 – 131. [3] S. Bludau, T. Dickscheid, F. Iannilli, and K. Amunts, In 22nd Annual Meeting of the Organization for Human Brain Mapping (OHBM), June 2016, 3D reconstruction of cell distributions in the human subthalamic nucleus at 1 micron resolution.