Capture of magnetic nanoparticles on ordered magnetizable arrays: A parametric study

This work is devoted to the experimental study of the magnetic separation of medium sized nanoparticles (40-70 nm) which are separated from the suspending fluid when the suspension flows through a micropillar array magnetized by an external magnetic field. The nanoparticle accumulation around micropillars is visualized and described by the capture efficiency and retention capacity, which are analysed in function of different dimensionless parameters, such as Mason number, dipolar coupling parameter, nanoparticle volume fraction, orientation of the flow with respect to the magnetic field and array's geometry. The role of these parameters is interpreted in terms of the interplay between hydrodynamic and magnetic interactions, as well as taking into account possible field-induced phase separation. The results could be useful for the development of the microscale magnetic separators for biomedical applications.