Sequential Batch Assembly of 3-D Microstructures by using a Magnetic Anisotropy and a Magnetic Field

This paper describes three-dimensional (3-D) microstructure assembly using an external magnetic field. An external magnetic field perpendicular to a substrate lifts a hinged structure by the torque due to the shape magnetic anisotropy. We made micro flap structures (4.5 μm-thick electroplated Permalloy) which have 0.2 μ,m-thick nickel elastic hinges in various size, and made lift the structures in a magnetic field up to 50 kA/m. We demonstrated that the non-dimensional factor depending on the volume of magnetic material and the stiffness of the hinges determine the sensitivity to the magnetic field. As a result, we realized sequential batch assembly using the difference of the sensitivity. The each two plates 600 μm x 600 μm in size were lifted sequentially, and out-of-plane microstructures were assembled. And the complex out-of-plan microstructures, the regular tetrahedrons 800 μm on a side with a closed linkage were able to assemble by our method.