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Press Release 057/2013

Researcher Construct Invisibility Cloak for Thermal Flow

Copper-Silicone Plate Deflects Heat / Optical Process Transferred to Thermodynamics / Basis for Future Heat Management in Microchips and Components
2013_057_KIT-Forscher_bauen_Tarnkappe_fuer_Waermefluss72dpi
Thermal invisibility cloak: Heat is passed around the central area from the left to the right. Temperature characteristics (white lines) remain parallel. (Figure: R. Schittny/KIT)

By means of special metamaterials, light and sound can be passed around objects. KIT researchers now succeeded in demonstrating that the same materials can also be used to specifically influence the propagation of heat. A structured plate of copper and silicone conducts heat around a central area without the edge being affected. The results are presented in the Physical Review Letters journal.

 

“For the thermal invisibility cloak, both materials have to be arranged smartly,” explains Robert Schittny from KIT, the first author of the study. Copper is a good heat conductor, while the silicone material used, called PDMS, is a bad conductor. “By providing a thin copper plate with annular silicone structures, we produce a material that conducts heat in various directions at variable speeds. In this way, the time needed for passing around a hidden object can be compensated.”

 

If a simple, solid metal plate is heated at the left edge, heat migrates uniformly to the right side. The temperature of the plate decreases from the left to the right. Exactly the same behavior is exhibited by the new metamaterial consisting of copper and silicone outside of the annular structure. No heat penetrates inside. Outside, there is no indication of what happens inside.

 

“These results impressingly reveal that transformation optics methods can be transferred to the highly different area of thermodynamics,” says Martin Wegener, Head of the Institute of Applied Physics of KIT. Here, the first three-dimensional invisibility cloak for visible light was developed. While optics and acoustics are based on the propagation of waves, heat is a measure of the unordered movement of atoms. Still, basic mathematical descriptions can be used to calculate the structures having the effect of an invisibility cloak. With the methods of so-called transformation optics, a distortion of the describing coordinate system is calculated. Arithmetically speaking, an extended object disappears in an infinitely small point. This virtual distortion can be mapped to a real metamaterial structure that passes incident light around the object to be hidden, as if it was not even existing.

 

“I hope that our work will be the basis of many further developments in the field of thermodynamic metamaterials,” Wegener says. Thermal invisibility cloaks are a rather new field in fundamental research. In the long term, they might be applied in areas needing effective heat management, such as in microchips, electric components, or machines.

 

Experiments on Transformation Thermodynamics: Molding the Flow of Heat, R. Schittny, M. Kadic, S. Guenneau, and M. Wegener, http://prl.aps.org/

 

 

Being „The Research University in the Helmholtz Association“, KIT creates and imparts knowledge for the society and the environment. It is the objective to make significant contributions to the global challenges in the fields of energy, mobility and information. For this, about 9,300 employees cooperate in a broad range of disciplines in natural sciences, engineering sciences, economics, and the humanities and social sciences. KIT prepares its 26,000 students for responsible tasks in society, industry, and science by offering research-based study programs. Innovation efforts at KIT build a bridge between important scientific findings and their application for the benefit of society, economic prosperity, and the preservation of our natural basis of life.

kes, 08.05.2013

For further information, please contact:

Kosta Schinarakis
Themenscout
Tel.: +49 721 608-41956
Fax: +49 721 608-43568
E-Mail:schinarakis@kit.edu
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