Magnetic Microparticle Transport on Disk Arrays in Time-Varying Magnetic Fields: Simulation and Experiment

Magnetic microspheres are fluid-borne magnetic particles, often made of iron oxide encased in polystyrene. These particles are designed for bioseparation of cells, proteins, DNA, and RNA, whereas they can be specifically bound to these targets allowing for field gradients to separate the particles from a mixture. Recent work has been done in the development of surface-based transport schemes and means of applying magnetic forces, showing promise for use in on-chip devices. We investigate particle motion on one such architecture, arrays of permalloy disks, aided by application of time-varying magnetic fields. I will discuss both long-range (100s of micrometer) and short range (<10 micrometer) microsphere transport on disk arrays. Furthermore, I will show comparison between computer models which simulate transport and observed behavior. Our model predicts limitations to particle speed due to phase-slipping motion, describes how transport depends on particle size, and suggests a means for estimating low-field magnetic susceptibilities of individual particles.