Abstract
This thesis aims at studying the breakup behavior of magnetic droplets and the rotary motion of magnetic particle chains under influences of magnetic film array underneath. Magnetic droplet split into smaller ones due to the induced magnetic hydrodynamic instability under an external field. The number of separated droplet increases with external field increasing, and the dimension of these droplets decreases. Through the assistance of magnetic film array, ordered hexagonal or square droplet array can be produced in numerous spacial densities depends on the film array design and applied field strength. In addition, field evolution of two-dimensional droplet lattice affected by magnetic films is also found and discussed. Three major ordered droplet lattices can be classified in our experiments. For applications, the ordered droplet array is well understood that is potential in bio-chip field as bioassay, besides, it also be used as the cast for polymer micro modeling. Moreover, rotary transportation of chain aggregation, which is composed of magnetic nanoparticles, between magnetic films is also demonstrated in this thesis. Under a magnetic field, magnetic nanoparticles tend to form the diopole-to-diopole structures, that is, the chain structures, for the energy minimization purpose. The stronger the field is, the longer the chain well be. The orientation of particle chain always follows the field direction, and rotary transportation of particle chain can be achieved by applying a rotating filed. Meanwhile, magnetic film array limits the chain’s walking step, and the transportation therefore becomes controllable. eywords: magnetic droplet, magnetic thin film, magnetic particle, magnetic hydrodynamic instability