Stepwise and Reproducible Magnetic Self-Assembly of Micropillar Arrays

초록

Magnetic self-assembly has been demonstrated for spherical colloidal particles and polymer composites by external magnetic field with advantage of remote controllability. However, magnetic interactions often prevent regular assembly of multi-objects. Toward stepwise and reproducible self-assembly, we employed magnetic micropillar arrays whose pillar-top is highly concentrated with magnetic particles while pillar-base is magnetically-inert. With response to external linear magnetic field, micropillars behave as dipolar micro-magnets, and subsequently, two adjacent micropillars are paired via quadrupolar magnetic attraction. As magnetic flux density increases, the closely arranged micropillar pairs are sequentially assembled to quad-body and eventually linearly connective architectures with long-range order. We will discuss governing parameters for the stepwise magnetic assembly including micropillar geometry, magnetic field threshold, and magnetic field angles.