Magnetic field induced motion of water droplets and bubbles on the lubricant coated surface

Diamagnetic water droplets placed on the silicone-oil-lubricated solid surfaces were displaced by a permanent magnetic field B≅0.4T. The motion was sensitive to the hydrophobicity of the solid surface. Maximal velocities vmax≅0.1-0.2mms were registered on the silicone-oil-lubricated hydrophobic surfaces. The maximal velocities were insensitive to the volume of water droplets for the volumes in the range of 2μl<V<12μl. The maximal velocities of the droplets were also only slightly dependent on the thickness of the oil layer. A model of the motion of diamagnetic droplets driven by the permanent magnetic field is suggested. The qualitative model describes satisfactorily scaling of the experimental findings. The reported process involves purely diamagnetic materials. Motion of silicone oil bubbles driven by the magnetic field is also reported.