Arranging Diamagnetic Particles in a Modulated Magnetic Field Originating in Microelectromechanical Systems Compatible with an Integrated Circuit upon Halbach Array Magnet.

In this study, we attempted to expand the applicability of the mechanism for arranging diamagnetic particles in a modulated magnetic field. A Halbach array magnet was prototyped as a portable device for generating a high magnetic field. Despite the magnet being palm-size with dimensions of 50 × 50 × 20 mm, the magnetic field is 1.31 T at 1 mm from the surface. Additionally, an Si substrate on which an Fe thin film is formed and patterned to be compatible with the integrated circuit (IC)-utilizing the microelectromechanical systems process technology-is prototyped as a tool to generate a modulated magnetic field. Regarding the deposition condition of the Fe thin film, holes with diameters of 30 μm are arranged in an array at intervals of 60 μm, and the thickness is approximately 0.5 μm. Finally, a particle magnetic-adsorption experiment was conducted using the prototypes. The diamagnetic particles (diameter: 25 μm) dispersed in the paramagnetic surrounding medium were observed to be arranged in the hole portions. This result indicates that the microparticles are absorbed in their arbitrary positions by the modulated magnetic field. In the end, we succeeded in achieving the portability and implementation on IC for the particle arrangement magnetic mechanism.