Electromagnet polarity dependent reversible dynamic behavior of magnetic liquid metal marble

We report reversible dynamic behavior of a magnetic liquid metal marble by changing magnetic field polarity. We coated iron (Fe) particles on the surface of the oxidized liquid metal by HCl-based chemical reaction to make it to be magnetized and to be non-wettable. We utilized electromagnets and changed current direction on-demand to change the magnetic polarity of the electromagnet. In 1-dimension (1-D), with an applied magnetic field of reverse polarity from the bottom, the conventional wetting shape of the magnetic liquid metal marble was observed, whereas the split was occurred with the applied magnetic field of same polarity due to attractive or repulsive force. With an applied magnetic field of reverse polarity, the split marbles was merged. By removing the magnetic field, the deformed magnetic liquid metal marble was recovered. The applied current dependent deformability and recoverability, and split and merge time were investigated. In addition, in 2-dimension (2-D), we observed various deformations and split behavior of the magnetic liquid metal marble with various magnetic field polarity combinations by utilizing electromagnets, which is reversible.