Field-directed and Template-assisted Magnetic Nanoparticle Self-assembly

X. Xue, E.P. Furlani
SUNY at Buffalo, US

Keywords: magnetophoresis, magnetic nanoparticle self-assembly, surfactant-surfactant contact, magnetic dipole-dipole interactions, high-gradient magnetic field, template-based magnetic particle assembly


The interest in field-directed assembly of colloidal magnetic nanoparticles has grown steadily in recent years due to a proliferation of applications including targeted drug therapy, biomedical imaging, among others. Such self-assembly holds promise as a low-cost and scalable approach for the fabrication of novel nanostructured materials with extraordinary magnetic, electrical and photonic properties. In this presentation, we show that the controlled self-assembly of magnetic nanoparticles into three-dimensional nanoscale patterns can be achieved using soft-magnetic microstructure templates. We demonstrate proof-of-principle using a computational model that predicts the assembly of the particles in the presence of high-gradient magnetic fields. We consider a prototype material concept wherein the field is produced by soft-magnetic ring like microstructures embedded in a substrate. At low concentrations, the particles form a single layer ring with even spacing between neighboring particles due to a repulsive dipole-dipole force. We also show 3D multilayer assemblies can be formed by increasing the particle concentration. We discuss various aspects of template-assisted assembly including the effects of particle size, volume fraction and the rational design of the template structure to achieve a required field gradient.