METAFLEX - Metamaterials on Flexible optically transparent substrate

Metamaterials (MMs) are man made materials with unusual electromagnetic properties that are not typically found in Nature. They are the key to achieving such extraordinary properties as invisibility cloaks and perfect lenses. At present, they are bulky and confined to laboratories. If they were flexible, they could become much more versatile and practical. Here, I propose a novel concept for flexible MMs that will turn current cloaking devices from suits of armour into true cloaks.The concept of index of refraction underpins the physics of MMs, which can be illustrated with an example. The direction that light takes when it crosses the interface between two media depends on its initial direction with respect to the surface and on the refractive indices of the media. This is the reason why a pencil appears to kink when immersed in water. In nature, all transparent materials have a positive refractive index, like water. As a result, the image of the pencil always kinks in the same direction. Conversely, MM are manufactured with a negative refractive index, thus in a MM the kink of the pencil would appear in the opposite direction. This effect, which may seem to be a mere curiosity, drives the extraordinary behavior of MMs.The technological requirements of currently fabricated optical MMs impose a flat rigid geometry. This impedes the realistic implementations of an optical cloak made of soft fabric, for example. I aim to overcome such limits.The aim of this project is to fabricate MMs in flexible, extremely thin membranes (METAFLEX).Metaflex will retain all the power of material design typical of MMs and their ability to control light, in a more flexible framework. I have already achieved the first milestone of the project and printed MMs on polymer flexible membranes with thickness down to few nanometers.The physics of Metaflex is a rich and unexplored field of research. This ambitious project is structured around their most striking properties:-Metaflex can be wrapped around objects and stacked, a vital step to realistic cloaking applications.-Metaflex stacks can be easily fine tuned after fabrication, e.g. via deformation, hence light can be controlled with additional degrees of freedom. The flexibility of Metaflex permits the design and fabrication of a camouflaging system, as the material response can sense and adapt to the surrounding environment. This offers a remarkable example of smart fabrics and intelligent textiles, currently a thriving area of research in academia and industry.-Metaflex provide a new framework to study the interaction between optical and mechanical forces, as in Optical Trapping or the new field of Optomechanics. Potential applications include very small optical microphones.-Metaflex are very light. They could take advantage of the attractive and repulsive forces triggered by optical beams in order to levitate and behave as nano-flying carpets. This would be a breakthrough in biomedical nano-applications such as drug-delivery and single molecules manipulation.My interest in Metaflex arises from diverse theoretical and experimental projects in photonic structures and nanofabrication and from the knowledge gained throughout these projects, including the physics and applications of MMs. This project contains many exciting scientific challenges, which offer the possibility of developing the extraordinary properties of MMs for every-day life applications that were unimaginable only a few years ago.

My research project deals with Metamaterials (MMs), i.e. materials with properties that can be engineered and cannot be found in Nature, for optical applications. The impact that MMs promise to have on everyday life can be effectively compared to examples including the invention of plastic or the ubiquitous use of lasers. For example, it has been shown that MMs can be used to create lenses with unlimited resolution and materials that can conceal objects, realizing invisibility cloaks. With this project I aim at developing flexible metamaterials (Metaflex) exhibiting the extraordinary optical properties of MMs in a more supple and versatile framework. The ambitious outcome of my research is to facilitate realistic applications of MMs to everyday life, in different fields and timescales. -The immediate recipients of this research will be commercial and industrial subjects involved in the technological sector. The MMs technology is already finding its way to commercial exploitation (for example to fabricate cheaper and more efficient antennas for networking applications), and Metaflex promises to boost in the next five to ten years its range of applicability. Few examples include the fabrication of miniaturized frictionless actuators, chemical sensors and a range of optoelectronic devices, like optical microphones. Potential commercial application of the most promising results will be pursued trough collaborations with local and National based companies, fostering wealth and economic competitiveness of UK. - Nanotechnologies are already heavily pursued in bio-applications. It is likely that Metaflex will contribute in a short timescale (5-10 years) in this direction as well. Collaborations with the Schools of Medical Science and Biology will help developing tools and protocols relevant to the field of nano-toxicology, an EPSRC signposted activity. Examples include ways of sensing and trapping nano-toxins and nano-pollutants. The same collaboration could lead to the development of visual prosthesis for augmented vision applications. These activities will have impact in sectors like health and environment protection, also with short- and long-term public economical benefit. - One obvious way to exploit the remarkable properties of Metaflex is for intelligence purposes, for example to implement cloaking and camouflaging techniques. While it is not suggested that on a short time scale it will be possible to conceal to the eye a macroscopic object, it is definitely already possible to look for efficient ways to apply the MMs paradigm to obtain an enhanced stealth technology, with strong impact on warfare and security fields. With the involved staff, we will be actively pursuing the diffusion of the outcome of my research to maximise its impact over the intended recipients, through participation to dedicated and generic Conferences, like PECS, CLEO and Photonic West. Frequent meetings (4/year) will be organized with project partners to discuss the results of the common activities. My host institution has recently appointed a Knowledge-Transfer team. I will seek advice of this dedicated staff, to maximise the chances of successful exploitation and early recognition of potential commercial applications and spinout activities. I have recently filed an application for a patent for a biomedical tool for endoluminal surgery; I will exploit this experience both to deepen the collaboration with subjects in the field and to pursue protection of intellectual properties connected to Metaflex. Finally, some extraordinary aspects of my research, like invisibility and camouflaging, easily engage with the imagination of the general audience. This will be further fostered through participation to National and International Science Festivals and outreach activities, involving schools and pupils of every grade and level.