Dynamics of rotating magnetic micro-bead chains

Super-paramagnetic colloidal particles aggregate into linear chains in the presence of a magnetic field and can act as intelligent micro-stirrers in micro-scale systems. In this paper, the dynamic behavior of the bead chains which is relevant for effective fluid mixing is shown to be largely influenced by the beads surface condition as well as by the fluid rheolo-gy. We found that Streptavidin coated beads show a good agreement with the prediction of numerical simulations, whereas Carboxyl coated beads exhibit a behavior similar to linked chains of magnetic particles that cannot rupture under viscous drag