Dynamic trajectory analysis of superparamagnetic beads driven by on-chip micromagnets

Abstract

We investigate the non-linear dynamics of superparamagnetic beads moving around the periphery of patterned magnetic disks in the presence of an in-plane rotating magnetic field. Three different dynamical regimes are observed in experiments, including (1) phase-locked motion at low driving frequencies, (2) phase-slipping motion above the first critical frequency f c1 , and (3) phase-insulated motion above the second critical frequency f c2 . Experiments with Janus particles were used to confirm that the beads move by sliding rather than rolling. The rest of the experiments were conducted on spherical, isotropic magnetic beads, in which automated particle position tracking algorithms were used to analyze the bead dynamics. Experimental results in the phase-locked and phaseslipping regimes correlate well with numerical simulations. Additional assumptions are required to predict the onset of the phase-insulated regime, in which the beads are trapped in closed orbits; however, the origin of the phase-insulated state appears to result from local magnetization defects. These results indicate that these three dynamical states are universal properties of bead motion in non-uniform oscillators. V C 2015 AIP Publishing LLC. [http://dx

Propulsion of microspheres in fluids using rotating magnetic fields

“…proteins [31]. Superparamagnetic beads on specially designed surfaces, which had a magnetic disk pattern, have been explored for potential use in cell separation for labon-a-chip [32]. These authors found a particle dynamics which looks similar to the one found in the present experiments, but the motion was limited to a small region around each magnetic disk of diameter 10-30 µm.…”

Measurement of the magnetophoretic velocity of different superparamagnetic beads

“…In these techniques, the beads usually act as labels. They can also be used as handles [3], for example to clean a solution [4] [5] or to deliver substances to a specific target [6]. In [7], it was shown that they can be used to enhance the adeno-associated viral vector delivery in human neural stem cell infection.…”

A novel magnetophoretic-based device for magnetometry and separation of single magnetic particles and magnetized cells

“…, a difference between the particle position on the disk perimeter and the external magnetic field angle). 41 At low frequencies ( i.e. , small phase lags), the particles experience a low phase lag and can follow the external field.…”