The Behavior of Nano- and Micro-Magnetic Particles Under a High Magnetic Field Using a Superconducting Magnet

Magnetic force has been used for drug delivery, magnetic separation, and other kinds of micro- and nano-particle handling. As fundamental studies of these applications, we have investigated the visualization of the motion of micro-magnetic particles under a dynamic magnetic field. We have also studied the contactless grasp of a micro-magnetic particle suspended in a fluid by using coil currents. In the study, we have developed a method for quantitatively estimating the influencing forces. However, these experiments have limitations in the magnetic field strength of normal conducting electromagnets or permanent magnets. Therefore, much higher magnetic force is needed for the application to drug delivery or cell/DNA manipulation. High magnetic field generating high magnetic force saturates the magnetization of magnetic particles during the particle control, and the magnetic saturation influences the particle behavior. However, such behavior of magnetic particles has not been sufficiently studied yet. In this paper, the behavior of the particles nearly or fully saturated under the high magnetic field of a superconducting magnet was visualized successfully, and ferrite and feeble magnetic particles were introduced in order to gain insight into their behavior.