Fabrication of magnetic microstructures by in situ crosslinking of magnetically assembled nanoparticles

Abstract

We present a photolithography-free fabrication technique to create magnetic microstructures using magnetically self-assembled iron oxide (Fe3O4) nanoparticles, which are subsequently crosslinked to each other via surface polymerization. This effort is a step toward low-cost roll-to-roll fabrication of free-floating micromagnetic actuators such as microswimmers, micro-stirrers, micro-tweezers, etc. Four main accomplishments are reported: (1) optimization of the particle deposition (self-assembly) conditions to achieve feature sizes down to 5 µm, (2) development of the polymerization process to crosslink the nanoparticles, (3) release of the microstructures from the substrate via a sacrificial layer, and (4) demonstration of the magnetic actuation of prototype structures.