Non-linear Dynamics of Traveling Wave Magnetophoresis for Applications in Colloidal Separation

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The research objective of this award is to investigate the non-linear dynamics of traveling wave magnetophoresis for applications in colloidal separation. The traveling magnetic field wave used in the proposed work is generated by superimposing a uniform rotating magnetic field with the local magnetic field near an array of micro-magnets. When the external field rotates at a low frequency, the magnetic beads become locked into the potential energy minima and move synchronously with the traveling wave. At higher frequencies, the magnetic beads tend to slip out of the potential energy minima, causing the bead to move less quickly or stop moving altogether. The overall goals of this proposal are to investigate the unexpected behavior recently observed in this ?slipping? regime, in which the beads display strongly non-linear transport behavior, and to use this non-linearity to explore a novel application in magnetic separation. Numerical simulations will be a dominant tool in this study both for interpreting the experimental results and for guiding future applications of this technique. If successful, the proposed work will lead not only to new methods for sorting magnetic beads based on size and/or the type of biological micro-organism attached to the bead, but will also reveal insight into unresolved problems in first order non-linear dynamical systems. Due to the highly interdisciplinary nature of this work, graduate and undergraduate students will have broad exposure to the fields of dynamics, electricity and magnetism, microfabrication, chemistry, biology and computer science. Minority studies from Historically Black College and Universities (HBCU?s) or Historically Minority Universities (HMU?s), will be included in this work for two summer months. In addition, undergraduate students from Duke University will participate in this research through the Duke University Pratt Fellows program.