Researchers from the University of Cambridge have devised a new method to stitch nanoparticles in a way that light is refracted in a wrong way so that it is rendered invisible. The key to any sort of invisibility effect lies in the way light interacts with a material. Lights’ absorption or reflection upon hitting a surface enables us to see objects. However, by engineering materials at the nanoscale, it is possible to produce 'meta–materials' that can control the way in which light interacts with them.
The technique developed by the Cambridge team involves stitching gold nanoparticles together into long strings and using unfocused laser light as billions of needles. These strings can then be stacked into layers much like the Lego bricks. In order to make the strings, researchers first used barrel–shaped molecules called cucurbiturils (CBs). The CBs act like the miniature spacers that locks nanoparticles in place by controlling the space between them.
When a laser is focused on the strings of particles in the CB scaffolds, it produces plasmons; ripples of electrons at the surfaces of conducting metals. These electrons concentrate light energy on atoms at the surface and join them to form bridges between the nanoparticles. Researchers state that they have achieved the control of dimensions in creating invisible devices in a way that has never been achieved before. Meta–materials have a wide range of potential applications, including sensing and improving military stealth technology.