A team of researchers headed by Martin Wegener, a Professor at the Karlsruhe Institute of Technology (KIT), has created a prototype of a pentamode metamaterial, a stable crystalline metafluid, paving the way to realize several 3D transformation acoustics ideas such as novel loudspeaker concepts, acoustic prisms and inaudibility cloaks.
Novel nanostructuring techniques help in realizing this new class of materials with exclusive mechanical properties for the first time. The study results will be published in the Journal, Applied Physics Letters.
Dr. Muamer Kadic, first author of the study, informed the research team used a polymer to produce the prototype. The material’s mechanical behavior relies on the length and acuteness of the individual ‘sugar loaves.’ To manufacture the metamaterial, the capability to design and connect nanometer-range sugar loaves with each other at right angles is essential. It is equally important that the whole structure has to grow as big as possible. The resulting composite is extremely lightweight due to the fact that material itself represents only just above 1% of the total volume.
Tiemo Bückmann, one of the members of the team, used a dip-in laser writing technique to realize the metamaterial’s structure. Direct laser writing devised by Wegener and his colleagues is the basis of the dip-in laser writing technique. Bückmann informed that metamaterials are essential for transformation acoustics to get 3D results similar to transformation optics. Considering this, the first pentamode metamaterial developed by the Karlsruhe team is a major achievement.
Using direct laser writing, Wegener and his colleagues created optical lithography of 3D nanostructures.