Translocation of magnetic beads using patterned magnetic pathways for biosensing applications

We have designed, fabricated, and demonstrated a novel system for translocation of magnetic beads at specific sites of the sensor surface on a single chip for biosensor applications. The soft NiFe elliptical (9 x 4 x 0.1 mu m(3)) elements are arranged as magnetic pathways connected to the model sensor surface. The patterned NiFe elements can generate different stray magnetic fields when they are subjected to the external rotating magnetic field. The inhomogeneity in stray magnetic fields can govern the magnetic bead motion on the pathways. We demonstrated the motion of Dynabead (R) M-280 magnetic bead on patterned pathways by controlling the external rotating magnetic field in clockwise and counterclockwise directions. The magnetic beads that were placed on the magnetic elliptical pathways are shown to be transported to the sensor surface, as well as be pulled out away from the surface. This technique enables microtranslocation of the magnetic beads coated with biomolecules to the specific binding sites of the sensor surface and as well as drive off the nonspecific binding biomolecules from the surface in performing number of sequential bead detection experiments for future integrated lab-on-a-chip systems. (C) 2009 American Institute of Physics. [DOI: 10.1063/1.3073965]