Pentamode Metamaterial Successfully Created For the First Time

Pentamode metamaterials almost behave like fluids. Their manufacture opens new possibilities in transformation acoustics. (KIT)

A new material from nanotechnology has been successfully created again. A new class of materials, pentamode metamaterial, which is made of crystal metafluid stable, successfully carried out by researchers at the Karlsruhe Institute of Technology (KIT). Research led by Professor Martin Wegener, has used a new method of nanostructuring. Conceptually, all conceivable three-dimensional mechanical materials can be built from pentamode materials. Pentamodes also enable to implement three-dimensional transformation elastodynamics—the analogue of transformation optics. However, pentamodes have not been realized experimentally before.

Success in making pentamode is a first step the new advances in the technology of the future. The reason, numerous three-dimensional transformation acoustics ideas, for example inaudibility cloaks, acoustic prisms or new loudspeaker concepts, could become reality in the near future.

The mechanical behavior of materials such as gold or water is expressed in terms of compression and shear parameters. Whereas the phenomenon that water, for example, can hardly be compressed in a cylinder is described through the compression parameter, the fact that it can be stirred in all directions using a spoon is expressed through the shear parameters.        

The word penta is derived from ancient Greek and means “five”. In the case of water, the five shear parameters equal zero, and only one parameter, compression, differs from that value. In terms of parameters, the ideal state of a pentamode metamaterial corresponds to the state of water, which is why that material is referred to as a metafluid. Theoretically, any conceivable mechanical properties whatsoever can be obtained by varying the relevant parameters.

“Realizing a pentamode metamaterial is about as difficult as trying to build a scaffold from pins that must not touch but at their tips,” first author Dr. Muamer Kadic explains. “The Karlsruhe prototype has been manufactured from a polymer. The mechanical behavior of the material is determined by the acuteness and length of the individual “sugar loaves”. On the one hand, we must be capable of designing small sugar loaves in the nanometer range and connect them to one another at the right angle. On the other hand, the entire structure must eventually become as large as possible. Since the material itself contributes only little more than one percent to the respective volume, the composite obtained is extremely light.

The stable four-leg structure (shown in orange) is the basic element of the pentamode metamaterial. It is arranged in the form of a three-dimensional adamantine crystal such that the resulting material as a whole can be formed. (Source: CFN, KIT)

“To obtain similar 3D results, as in transformation optics, transformation acoustics is exclusively dependent on metamaterials. In view of this, this first manufacture of our pentamode metamaterial is a quite significant success,” adds Tiemo Bückmann, who is about to receive his diploma at the Institute of Applied Physics and is responsible for realizing the structures of the new material by means of dip-in laser writing, a method that has been derived from direct laser writing developed by the Nanoscribe company.

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This story has edited by author of threelas

Source: KIT

Publication: http://dx.doi.org/10.1063/1.4709436

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