Methods and Apparatus for Controlling Dispersions of Nanoparticles

A cloaking apparatus, comprising:

• a structure formed of a transparent body having a cavity with a metamaterial provided in the cavity, the metamaterial being a mixture of at least one dielectric fluid and a plurality of metal nanoparticles, with inner and outer electrodes and a voltage source to selectively produce at least one electric field across the metamaterial.

A method of cloaking an object, the method comprising:

• providing a structure having a cavity in which a metamaterial formed of a plurality of metal nanoparticles is disposed in a soft dielectric material is disposed to allow the metal nanoparticles to move with the dielectric material,
• providing a system for generating at least one electric field in the metamaterial,
• disposing the object to be cloaked interior of the cavity such that the structure is positioned between the object and an observer, and selectively applying an electric field such that the metamaterial has a permittivity that depends on the radial coordinate.

An optical apparatus comprising

• a structure formed of a transparent body having a cavity with a metamaterial provided in the cavity, the metamaterial being a dispersion of at least one dielectric fluid and a plurality of metal nanoparticles,
• inner and outer electrodes and a voltage source to selectively produce at least one electric field across the metamaterial in the cavity, wherein application of the at least one electric field allows reconfiguration of the properties of the metamaterial.