Bi-layer steady state current cloak

We report that bi-layer copper and polystyrene cylinders can cloak steady current. We fabricated two hollow cylinders, the one made of copper, and the other made of polystyrene. Two hollow copper and polystyrene cylinders nested concentric bi-layer hollow copper and polystyrene cylinders. The background media are made of aluminum. Theory and experiment demonstrated that the electric potential gradients are parallel and equal outside the outer circle, the iso-potential lines are parallel outside the outer circle, and the electric potential is zero in the inner circle. (C) 2014 Elsevier B.V. All rights reserved.