In the top image, the graded index nanocomposite has been applied and there is a reduction in the amount of shadowing seen immediately after the object, as well as a noticeable improvement in the reconstruction of wave fronts. The effect is to 'cloak' the object: such a structure can hide an object that would ordinarily have caused the wave to be scattered. In the bottom image, the cloak is not being used and so the object along the path of the traveling wave can be seen, drastically changing its electric field configuration. Images: QMUL.Scientists at Queen Mary University of London (QMUL) in the UK have made an object disappear using a composite material with nano-sized particles that can enhance specific properties on the object's surface.
Working with the UK technology company BAE Systems, researchers from QMUL's School of Electronic Engineering and Computer Science have demonstrated for the first time a practical cloaking device that allows curved surfaces to appear flat to electromagnetic waves. They report their work in a paper in Scientific Reports.
While the research might not yet lead to the invisibility cloak made famous in J.K Rowling's Harry Potter novels, this practical demonstration could result in a step-change in how antennas are tethered to platforms. It could allow for antennas of different shapes and sizes to be attached in awkward places and to a wide variety of materials.
"The design is based upon transformation optics, a concept behind the idea of the invisibility cloak," explained co-author Yang Hao from QMUL's School of Electronic Engineering and Computer Science. "Previous research has shown this technique working at one frequency. However, we can demonstrate that it works at a greater range of frequencies making it more useful for other engineering applications, such as nano-antennas and the aerospace industry."
The researchers coated a curved surface with a nanocomposite possessing seven distinct layers (termed a graded index nanocomposite), where the electric property of each layer varies depending on its position. The effect is to 'cloak' the object: such a structure can hide an object that ordinarily would have scattered electromagnetic waves.
The underlying design approach also has much wider applications, ranging from microwaves to optics for the control of any kind of electromagnetic surface waves.
"The study and manipulation of surface waves is the key to develop technological and industrial solutions in the design of real-life platforms, for different application fields," said first author Luigi La Spada, also from QMUL's School of Electronic Engineering and Computer Science. "We demonstrated a practical possibility to use nanocomposites to control surface wave propagation through advanced additive manufacturing. Perhaps most importantly, the approach used can be applied to other physical phenomena that are described by wave equations, such as acoustics. For this reason, we believe that this work has a great industrial impact."
This story is adapted from material from Queen Mary University of London, with editorial changes made by Materials Today. The views expressed in this article do not necessarily represent those of Elsevier. Link to original source.