Invisible items sound like they belong in a fantasy world like Harry Potter, but now the dream is nearly a reality!
I am confident at one point or another during our childhood that every one of us wished to have an invisibility cloak or device. The ability to secretly move around and access all kind of restricted areas was a daydream for us. As expected, this concept aroused the interest of the scientific community, prompting many studies on the matter,,, and producing the famous “meta-materials”. These new materials are able to bend electromagnetic radiation, such as light, around an object which alters the way it’s perceived by the naked eye. Yet, previous ‘invisibility cloaks’ designed by transformation optics are usually bulky and rely on complex spatial distributions of material parameters to hide an object.
Recently, meta-surfaces were developed. These ultrathin metamaterials composed of tailored planar microstructures have demonstrated extraordinary abilities to control the phase, amplitude, and polarisation of electromagnetic waves,,. Nowadays, with the use of metasurfaces, the thickness and complexity of invisibility cloaks have been significantly reduced and the results are much more effective.
The newly developed metamaterials are covered in miniature nanoantennas made up of gold blocks. The fluctuating size of the blocks neutralises the distortion of light after it hits the cloak, thus hiding the contours and detail of the object beneath the cloak. It could theoretically also be used to perform the opposite — turning a 2D image into 3D one, making it ideal for use holographic displays and virtual reality.
Many useful applications have been considered for this cloak, for example within Healthcare; like coating internal organs so that surgeons can easily see what lies behind them since the silk is not rejected by the human body, or developing a ‘super lens’ used to detect live viruses in action and maybe even aspects of our DNA.
Although we’re still a long way from a magical cloak you can wrap yourself in to become invisible, this recent discovery brings us one step closer to achieving a long-standing fantasy dream for humans: invisibility!
Nadia, Consultant, Leyton France
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