Abstract
Spatial tailoring of the material constitutive properties is a well-known strategy to mold the local flow of given observables in different physical domains. Coordinate-transformation-based methods (e.g., transformation optics) offer a powerful and systematic approach to design anisotropic, spatially inhomogeneous artificial materials (metamaterials) capable of precisely manipulating wave-based (electromagnetic, acoustic, elastic) as well as diffusion-based (heat) phenomena in a desired fashion. However, as versatile as these approaches have been, most designs have thus far been limited to serving single-target functionalities in a given physical domain. Here, we present a step towards a “transformation multiphysics” framework that allows independent and simultaneous manipulation of multiple physical phenomena. As a proof of principle of this new scheme, we design and synthesize (in terms of realistic material constituents) a metamaterial shell that simultaneously behaves as a thermal concentrator and an electrical “invisibility cloak.” Our numerical results open up intriguing possibilities in the largely unexplored phase space of multifunctional metadevices, with a wide variety of potential applications to electrical, magnetic, acoustic, and thermal scenarios.
- Received 30 December 2013
DOI:https://doi.org/10.1103/PhysRevX.4.021025
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Published by the American Physical Society
Popular Summary
Metamaterials are artificially engineered materials that can alter the properties of both wave-based and diffusion-based phenomena. Such materials promise formidable advances in a variety of fields, including optics, acoustics, elastodynamics, and heat transmission, thanks to their ability to induce unconventional responses that cannot be replicated in nature (“invisibility cloaking,” for instance). While traditional metamaterials thus far have been largely limited to altering only one type of phenomenon at a time, we have designed a metamaterial shell that simultaneously induces unique changes in both the thermal and electrical regimes.
We conducted numerical simulations of a metamaterial annular shell with radii and composed of graphite, carbon fiber, and aluminum nitride, among other materials. We find that the shell is able to both concentrate heat flux within its inner region and bend electrical current around that region, simultaneously behaving like a thermal concentrator and an electrical invisibility cloak. These results open up new perspectives in the engineering of thermoelectric materials, as well as the design of complex multifunctional devices and components.
Metamaterials can be constructed over size scales ranging from atoms to macroscale composites, providing a wide range of physical domains for exploring the distinctly non-natural characteristics of these materials. Our simulations furthermore indicate that metamaterials can be fabricated by means of small sub-blocks made of presently available materials, bringing practical design within reach of current fabrication technologies.
