Spiral-type micro-machine for medical applications

The spiral-type magnetic micro-machine, which is driven by a rotating magnetic field, is characterized by their wireless operation for swimming. The machine have to swim under the lower Reynolds number (Re) environment, when the machine is downsized and work inside the human body. In this study, using various silicone oils whose kinematic viscosity ranged from 1 to 5x10(6) mm(2)/s, swimming performance of the machine on low Reynolds number was examined. The machine composed of a cylindrical NdFeB magnet could swim in the oils under condition of Re=10(-7). This Reynolds number is same as that of a micro-machine with micron size swimming in the water In addition, the machine could turn by controlling the external rotational magnetic field, therefore the swimming direction of the machine could be controlled. Using these principles, a magnetic micromachine, which can run in a gel, was also fabricated.