A microfluidic system includes a magnetic source (150) and two chambers (110) that are connected by a channel. The chambers and the channel are filled with different fluids such that a non-zero surface tension is created at the associated fluidic interfaces. Moreover, the magnetic source (150) is arranged to provide at least two separate magnetic gradient regions (GR) and to allow for the attraction of magnetic particles (MP) present in one of the chambers into these different regions. The magnetic forces (F) generated by at least one of the gradient regions (GR) is strong enough to allow for pushing or pulling magnetic particles through the fluidic interfaces. The magnetic source may be realized by a permanent magnet (150) of hexahedral shape. A method achieves dispersion and re-accumulation of an ensemble of magnetic particles in the microfluidic system.