Examining flow dynamics of platelet function in micro-contractions using micro-PIV

This study examines the flow field in the near-vicinity of microcontraction-expansion geometries in microfluidic devices designed to specifically examine the impact of flow acceleration on platelet function. To this end, a set of Micron-resolution Particle Image Velocimetry (micro-PIV) measurements is conducted under a specific set of shear flow gradient conditions with both Newtonian (water) and non-Newtonian (blood analog solutions) fluids. These experiments are complemented by numerical simulations and a set of measurements at matched conditions using blood platelets labelled with DiOC6 (1µg/mL), introduced into the citrated human whole blood. Preliminary results reveal a good agreement between the experiments and numerical simulations at matched flow conditions. However, the experiments with blood analog solutions appear to exhibit different flow patterns both downstream and upstream of the micro-contractions. Furthermore, comparisons between the micro-PIV and blood flow experiments reveal that platelet aggregation appears to coincide with regions of high strain rate and wall shear stress. Collectively, these findings provide a better understanding of the appropriate simplifications that can be made in numerical and experimental work and provides a platform for future works to better understand the impact of flow acceleration on platelet activation.