Planar coil-based microsystem for the long-range transport of magnetic beads

We propose a new approach for magnetic microbead transport in microfluidic channels over long-range distances by the actuation of a simple array of planar coils. The latter are placed in a uniform static magnetic field, generated by permanent magnets. This static field imposes a magnetic moment with a fixed sense to the microbeads. As a consequence, the magnetic energy and the magnetic forces acting on the beads are strongly enhanced, when the beads are placed in a spatially varying field. Only the very small magnetic field gradient of a simple planar coil is then sufficient to displace the beads over many millimeters.