Noncontact manipulation of Ni nanowires using a rotating magnetic field

Ni nanowires (NWs) are driven in water using a rotating magnetic field. The NWs show various locomotion performances under different boundary conditions. Pure rotation occurs when the two ends of the NWs are homogenously constrained. However, if the boundary conditions are different at the two ends of the NWs, tumbling motion, i.e., rotation plus translation, will be generated, which leads to the propulsion of NWs near a wall. These motions of NWs can be steered by the magnetic field. In addition, we present that the two NWs self-assemble to form a single NW with the magnetic field. The results imply that magnetic field is a promising approach for noncontact manipulation of Ni NWs or other 1-D ferromagnetic nanostructures at low Reynolds number aqueous environment in a controllable fashion.