Local control of magnetic objects in microfluidic channels

The application of magnetic fields in microfluidics is of growing interest and the localisation of the applied field emerges as a key requisite for future integration with other micro-platforms. In this paper, we present a novel strategy of fabrication of an integrated microchannel, which combines the advantages of localisation of the magnetic field with simplicity of design and fabrication. The circuit is fabricated in one single step using a copper plate dedicated to microelectronics. We determine the magnetic field inside the microchannel by numerical simulations computed for this novel design. Magnetic beads in the microchannel are driven into movement by a magnetic force in the range of a few picoNewtons. We have checked that the magnetic force is well localised by following bead trajectories when they approach the magnetic area. Moreover, as a proof of concept, quantitative magnetic cell sorting was successfully performed in the microchannel.