The use of a linear Halbach array combined with a step-SPLITT channel for continuous sorting of magnetic species

The Quadrupole Magnetic Sorter (QMS), employing an annular flow channel concentric with the aperture of a quadrupole magnet, is well established for cell and particle separations. Here we propose a magnetic particle separator comprising a linear array of cylindrical magnets, analogous to the array proposed by Klaus Halbach, mated to a substantially improved form of a parallel plate SPLITT channel, known as the step-SPLITT channel. While the magnetic force and throughput are generally lower than for the QMS, the new separator has advantages in ease of fabrication and the ability to vary the magnetic force to suit the separands. Preliminary experiments yield results consistent with prediction and show promise regarding future separations of cells of biomedical interest.

Research highlights
► Novel pairing of an adapted linear Halbach magnet array and step-SPLITT channel is carried out.
► Unlike QMS, it allows variation in mean magnetic force as well as the gravity component.
► The magnetic force is easily controlled by varying the channel-magnet distance.
► Magnetic particle separations behave predictably when varying the flow rate and distance.
► Separations match prediction with good enrichment of magnetic particles in mixture.