Microfluidic-based laser speckle contrast imaging of erythrocyte flow and magnetic nanoparticle retention in blood

The present study aims to develop a microfluidic system in combination with laser speckle contrast imaging (LSCI) for the study of erythrocyte dynamics under various physiological flow conditions. Microfluidic device was fabricated and red blood cell suspension was introduced at various flow rate controlled by a syringe pump. Relative blood velocity profile in the microfluidic chamber was obtained by LSCI in a real-time manner and correlated well with simulated results by computational fluid dynamics. A close correlation of relative blood velocity, inlet flow rate and blood viscosity were found using this microfluidic-based LSCI system. In addition, our platform also allows the demonstration of spatiotemporal variation of blood flow in response to magnet-induced magnetic nanoparticle (MNP) retention. The flow behaviour of erythrocytes with the presence of MNPs appeared to be closely correlated with the location of the magnet placement. Our microfluidic-based LSCI measurement represents a simple yet controllable experimental model for evaluating the variations in different hemorheological conditions in vitro and has a strong potential as an easy-to-use tool for investigating local MNP retention and hemodynamic changes.