Motion of magnetic motors across liquid-liquid interface.

Hypothesis: In a number of applications related to chemical engineering and drug delivery, magnetic nanoparticles should move through a liquid-liquid interface in the presence of surfactant molecules. However, due to the action of capillary forces, this is not always possible. The mechanism of particle motion through the interface essentially depends on the intensity of the Marangoni flow, which is induced on the interface during its deformation.

Experiments: In this paper we study the motion of nanoparticles FeO through the water-tridecane interface under the action of a nonuniform magnetic field when using different surfactants.

Findings: If the linear size of the magnetic motor turns out to be less than a certain critical value, then it is not able to move between phases due to the action of capillary forces on the interface. Depending on the type and concentration of the surfactant used, various mechanisms for the motor motion through the liquid-liquid interface can be carried out. In one of them, a liquid phase is transferred through the interface along with a movable motor, while in the other, it is not.