A microfluidic technique for measuring fiber-level mass transport efficiency and hemolysis of blood oxygenators

Extracorporeal Membrane Oxygenation (ECMO) serves as a standard intervention to manage severe cardiorespiratory diseases. While substantial research has been devoted to the understanding of oxygenator hemodynamics, there is a major gap in our understanding of mass transfer at cellular and hollow fiber levels. Due to the complex gas transfer pathway, from the microscopic hollow fibers to blood plasma and eventually to hemoglobin, experimental studies as presented here are extremely valuable. Therefore, the present study aims to develop a microfluidic system to investigate gas exchange efficiency, hemodynamics, and hemolysis around hollow fibers at the microscopic level. Five hollow fiber winding patterns were fabricated in a novel crossflow microfluidic channel system. Transient convective gas exchange efficiency in high hematocrit human blood was measured through a spatial oxygen sensor mounted to the inner surface of the channel. Simultaneous flow field mapping and red blood cell deformation assessment were performed using Optical Coherence Tomography combined with microscopic Particle Image Velocimetry. One-way ANOVA revealed significant differences in oxygenation efficiency across fiber patterns. Circumferential 45° (mean±SD, 1.27±0.05) showed significantly higher oxygenation efficiency compared to Circumferential 65° (0.88±0.04), Helical 45° (1.10±0.08), Helical 65° (0.95±0.12), and Polar 30° (0.78±0.02). Additional pairwise comparisons showed statistically significant variations among all configurations. Mass-weighted hemolysis analysis showed higher rates for 65° winding patterns compared to the 45° patterns, aligning with observed differences in oxygenation rates. These findings quantitatively demonstrate, first-time-in the literature, that the winding pattern and angle of hollow fibers significantly influence both oxygenation efficiency and hemolytic potential.