Microfluidic mixing using an array of superparamagnetic beads

We present a combined numerical and experimental study on the dynamics of superparamagnetic beads in a microfluidic channel, wall of which is decorated with an array of stationary magnetic disks. When exposed to a rotating magnetic field, the beads circulate around the magnetic disks. We conduct experiments with micrometer-sized supeparamagnetic beads and use a numerical method that is based on the lattice Boltzmann model to examine the dynamics of this microfluidic system. We isolate the conditions in which beads exhibit stable periodical motion around magnetic disks and probe the effect of microchannel flow on the bead dynamics. We demonstrate that the fluid circulations created by rotating beads can be exploited for microfluidic mixing, thereby offering a new approach for designing highly-efficient active microfluidic mixers.