Extreme Metasurfaces Enable Targeted and Protected Wireless Energy Transfer

Controlling the electromagnetic properties of materials beyond those achievable with natural substances has become a reality with the advent of metamaterials. The extreme properties that metamaterials provide offer an opportunity to manipulate and tailor electromagnetic waves in an arbitrary manner. Wireless energy transfer demands reliable and stable solutions for charging batteries of electronic devices with high efficiency and no effect on people, animals, plants, etc. Motivated by this challenging problem, a novel approach of using metamaterials with extreme parameters is suggested to enable targeted wireless energy transfer with reduced impact on biological tissues. Epsilon-near-zero (ENZ) and epsilon-and-mu-near-zero (EMNZ) metamaterials are designed and experimentally implemented, providing an energy transmission if and only if both the transmitter and the receiver are equipped with these metamaterials. The nonexistence of these extreme parameter metamaterials in nature protects the system from the presence of other objects with "ordinary" (effective) parameters causing neither noticeable change in operation nor any detrimental effect on foreign objects. The system behind the proposed approach can be realized in virtually any frequency band by appropriate scaling and suitable choice of material. This technology will find applications in targeted wireless energy transfer systems, especially where high power is needed, including electric vehicles.