Materials 2011, 4, 390-416; doi:10.3390/ma4020390 OPEN ACCESS materials ISSN 1996-1944 www.mdpi.com/journal/materials Article Electro-Optic Effects in Colloidal Dispersion of Metal Nano-Rods in Dielectric Fluid Andrii B. Golovin 1, Jie Xiang 1,2, Heung-Shik Park 1,2, Luana Tortora 1, Yuriy A. Nastishin 1,3, Sergij V. Shiyanovskii 1 and Oleg D. Lavrentovich 1,2,* 1 Liquid Crystal Institute, Kent State University, Kent, OH 44242, USA; E-Mails:
[email protected] (A.B.G.);
[email protected] (J.X.);
[email protected] (H.-S.P.);
[email protected] (L.T.);
[email protected] (Y.A.N.),
[email protected] (S.V.S.) 2 Chemical Physics Interdisciplinary Program, Kent State University, Kent, OH 44242, USA 3 Institute of Physical Optics, 23 Dragomanov Str. Lviv, 79005, Ukraine * Author to whom correspondence should be addressed; E-Mail:
[email protected]; Tel.: +1-330-672-4844; Fax: +1-330-672-2796. Received: 3 November 2010; in revised form: 3 February 2011 / Accepted: 10 February 2011 / Published: 14 February 2011 Abstract: In modern transformation optics, one explores metamaterials with properties that vary from point to point in space and time, suitable for application in devices such as an “optical invisibility cloak” and an “optical black hole”. We propose an approach to construct spatially varying and switchable metamaterials that are based on colloidal dispersions of metal nano-rods (NRs) in dielectric fluids, in which dielectrophoretic forces, originating in the electric field gradients, create spatially varying configurations of aligned NRs. The electric field controls orientation and concentration of NRs and thus modulates the optical properties of the medium.