A striking method of building materials with the help of light, developed by the scientists from University of Cambridge, could one day effectively enable technologies which are often considered as an integral part of any science fiction book like invisibility cloaks and cloaking devices to name a few.
The work got published in the journal Nature Communications.
The 'invisible’ effect comes from the way light interacts with a material. As light hits any surface, it gets either absorbed or reflected, which in turn makes the object visible.
But by manipulating materials at the nanoscale level, 'metamaterials' are generated that controls the way light interacts with them. Light reflected by a metamaterial is refracted in the 'wrong' way, potentially making the object invisible.
Metamaterials have huge applications in sensing and improving military stealth technology.
“According to the report by Science Daily, the technique developed by the Cambridge team involves using unfocused laser light as billions of needles, stitching gold nanoparticles together into long strings, directly in water for the first time. These strings were made by barrel-shaped molecules called cucurbiturils (CBs). In order to connect them electrically, the researchers needed to build a bridge between the nanoparticles. Conventional welding techniques would not be effective, as they cause the particles to melt. "It's about finding a way to control that bridge between the nanoparticles," said Dr Ventsislav Valev of the University's Cavendish Laboratory, one of the authors of the paper. "Joining a few nanoparticles together is fine, but scaling that up is challenging."
The cucurbiturils controls the bridge. When the laser is focused on the strings of particles in their CB scaffolds, it generates plasmons which are defined as ripples of electrons at the surfaces of conducting metals. These electrons concentrate the light energy on atoms at the surface and join them to form bridges between the nanoparticles.
"Science Daily reports; we have controlled the dimensions in a way that hasn't been possible before. This level of control opens up a wide range of potential practical applications, said Dr Valev "