Researchers in Northern University in Evanston, Illinois, have created a new type of metamaterial with an outstanding quality: negative compressibility, which means the material compresses when stretched and expands when pushed.
For those who don’t know, a metamaterial is a synthetic material with a special structure that allows it to have different characteristics to those of natural materials.
This is not the first time a metamaterial with these properties has been built, but it’s the most successful one. Previous attempts to form this stable metamaterial have been carried out, but they had to have very specific vibrations, whilst this new type just needs a steady force.
To make such a unique material, scientists have created a design to make such special characteristics take place.
It consists of s row of 4 particles with attraction between each other. The two inner particles have a weak attraction force, so any slight force (like pulling the material) breaks the bond. But when this happens, the outer particles attract more to each other, so the material actually compresses.
Vice versa, if the material is squeezed the two inner particles create another bond, repel, and cause the material to expand
This type of metamaterial has many uses, which could go from making cushions that expand when you sit on them to protective cats on military vehicles, so if a something hit the car or tank, the metamaterial will push it back and reduce some of the effect.
However, this material is not the only famous metamaterial that has been made. A few months ago, scientists developed the so called ‘invisibility cloak’, made of silver nanowires in porous aluminium oxide, which could deviate light rays and make objects behind the material invisible.
But, what both have in common, is that the general population won’t be able to buy them, as they still need to be improved and will only be used for the government and the army.
If you haven’t understood quite clearly the internal model of this material, you can see the diagram created by Zachary Nicolau and Adilson Motter (the designers of this material):