Microscale Visualization of Erythrocyte Deformation by Colliding with a Rigid Surface Using a High-Speed Impinging Jet

Erythrocyte deformation by colliding with a rigid surface using a high-speed impinging jet was studied with microfluidic techniques. We aim to investigate the relevance of colliding erythrocytes with hemolysis. A micro-channel chip was made of polydimenthyl-siloxane (PDMS), which comprised a T- and Y-shaped junction with a micro-nozzle and diffuser in order to attain a high-speed microflow with a jet velocity of m/s scale. A high-speed camera with a microscope imaged colliding erythrocytes by shadow imaging. Porcine erythrocyte with a hematocrit of 0.5 % in phosphate buffer saline was utilized. At the Y-junction, erythrocytes showed buckling due to an impulsive, longitudinal, compressive deformation. Such anomalous phenomena were not detected at the T-junction, where erythrocytes underwent sequential compressions as approaching the colliding surface. Erythrocyte after buckling showed a hazy membrane while being released from the colliding surface, suggesting the ejection of hemoglobin out of the pore on a membrane. Flow-induced hemolysis has been considered as a model of viscous shear stress and exposure time. From our data, however, it was suggested that hemolysis due to a high-speed impinging flow characterized by mechanical heart valve flows may arise as an impulsive failure of erythrocyte membrane upon collision.