The purpose of this project is the development of novel strategies to manufacture devices that render the unauthorised duplication or falsification more difficult. With the rapidly increasing quality of publicly available replication technology (e.g. colour printers and photo-copying machines), the counterfeit of bank notes and identity documents is becoming and increasing problem. To counteract this field of organised crime, new approaches to manufacture security documents are necessary.In a collaboration with the world's largest security printer and paper maker, De La Rue, the objective of this project is to develop novel devices for security documents. Based on techniques that are available in Prof. Steiner's laboratories, surface patterns will be developed that show a brilliant coloured effect that change when the angle of illumination or observation is changed. This effect arises from the interference of white light on a surface with a micrometre-sized dielectric pattern. To achieve this a combination of strategies are planned, including the use of fluorescent nanoparticles, multilayer structures, lateral gratings, etc., all deposited by spin-coating, or soft lithographic methods.

The use of colour in every consumer product is ubiquitous. However with increasing concern for the environment, the use of traditional dyes is becoming problematic. This has opened up new opportunities in producing colour by carving out materials at scales smaller than a millionth of a metre, built of components which are benign. In addition, the new possibilities available for structural colours (iridescent, prismatic, multi-hue, or luminescent) are universally attractive in competitive marketplaces such as mobile electronics, fashion, and automotive/airline industries.We have invented a new process for making plastic films which have appealing structural colours, that can be scaled up to industrial production levels. It is based on making periodic arrangements of stacked nano-spheres with a different optical density to their surroundings, called 3D photonic crystals. Until now, there has been no way to make industrial-scale cheap photonic crystals. Our method is based on making plastic sphere precursors which can be heated and extruded together in such a way that they slide over each other into perfectly packed arrays. By adding tiny nano-particles (hundreds of times smaller in size) in between the spheres we can make an enormous variety of new sorts of materials or fibres which have 'smart' colour. For instance, the films are elastic and they drastically change colour when they are stretched, or are bent.In order to realise the possibilities in our discoveries, we need to find out how to properly control this shearing-assembly of polymer nanoparticles, by testing out the extrusion on a reasonable scale while measuring optically how it is taking place. We also need to develop ways to extrude fibres that could be used for making iridescent fabrics. Only when we understand the mechanisms in detail will we know enough to scale up production to the level that industry wants to see before investing further in commercial manufacture. We can also make a variety of even more intriguing films, including ones which glow with different colours, or are magnetic. We also need to show how the films might decompose to see what environmental issues might be raised by releasing such material on a widespread basis. Finally we need to develop a plan for which particular applications that we should concentrate on, in collaboration with a number of large companies.Everyone who we show these rubbery iridescent films to, wants a piece to take away with them. We want to be able to provide films to everyone, by commercialising our nanomaterials research and development.

Visible light can be made to interact with new solids in unusual and profoundly different ways to normal if the solids are built from tiny components assembled together in intricately ordered structures. This hugely expanding research area is motivated by many potential benefits (which are part of our research programme) including enhanced solar cells which are thin, flexible and cheap, or surfaces which help to identify in detail any molecules travelling over them. This combination of light and nanoscale matter is termed NanoPhotonics.Until now, most research on NanoPhotonics has concentrated on the extremely difficult challenge of carving up metals and insulators into small chunks which are arranged in patterns on the nanometre scale. Much of the effort uses traditional fabrication methods, most of which borrow techniques from those used in building the mass-market electronics we all use, which is based on perfectly flat slabs of silicon. Such fabrication is not well suited to three-dimensional architectures of the sizes and materials needed for NanoPhotonics applications, and particularly not if large-scale mass-production of materials is required.Our aim in this programme is to bring together a number of specialists who have unique expertise in manipulating and constructing nanostructures out of soft materials, often organic or plastic, to make Soft NanoPhotonics devices which can be cheap, and flexible. In the natural world, many intricate architectures are designed for optical effects and we are learning from them some of their tricks, such as irridescent petal colours for bee attraction, or scattering particular colours of light from butterfly wings to scare predators. Here we need to put together metal and organics into sophisticated structures which give novel and unusual optical properties for a whole variety of applications.There are a number of significant advantages from our approach. Harnessing self-assembly of components is possible where the structures just make themselves , sometimes with a little prodding by setting up the right environment. We can also make large scale manufacturing possible using our approach (and have considerable experience of this), which leads to low costs for production. Also this approach allows us to make structures which are completely impossible using normal techniques, with smaller nanoscale features and highly-interconnected 3D architectures. Our structures can be made flexible, and we can also exploit the plastics to create devices whose properties can be tuned, for instance by changing the colour of a fibre when an electrical voltage is applied, or they are stretched or exposed to a chemical. More novel ideas such as electromagnetic cloaking (stretching light to pass around an object which thus remains invisible) are also only realistic using the sort of 3D materials we propose.The aim of this grant is bring together a set of leading researchers with the clear challenge to combine our expertise to create a world-leading centre in Soft NanoPhotonics. This area is only just emerging, and we retain an internationally-competitive edge which will allow us to open up a wide range of both science and application. The flexibility inherent in this progamme grant would allow us to continue the rapid pace of our research, responding to the new opportunities emerging in this rapidly progressing field.

It is a major problem to exploit the new ideas emerging from the Photonics/Plasmonics/Metamaterials academic community (in which the UK is strong) for real-world applications. In this field, the intricate structure of metals and dielectrics on the nanoscale produces radically new optical properties which are the basis for many devices and materials. However because the nanoscale architectures are designed by academics with little thought to manufacturability, most of these ideas founder very early against cost, method and volume considerations. We aim to invert this model, examining much more seriously a number of different fabrication routes that look promising for delivering scale-up of manufacturing nanostructures with novel and useful photonic materials and metamaterials functionality. However, blind approaches from considerations only of manufacturability are unlikely to locate useful functionalities. As a result we are strongly guided by a set of successful platforms developed over the last 5 years, which already embed the promise of scale-up due to their use of bottom-up self-assembly. In this programme, we develop such directed-assembly towards real capabilities for manufacturing. Success in this domain will be directly exploited by a number of UK companies, both large and small, but even more importantly will be transformative for UK approaches to manufacturing. Despite huge investments in top-down nanofabrication in the UK, little commercial return has been produced. Alternative approaches based on self-assembly already have traction (for instance inside Unilever), and offer routes to mass-scale production with a cost model that is realistic. What industry needs is not the ideas, but a well-developed research programme into the manufacturing space that will allow them to make use of these advances. Our programme will deliver this through tightly coupling nanoassembly, nanophotonics, and nano-manufacturing.

Abstracts are not currently available in GtR for all funded research. This is normally because the abstract was not required at the time of proposal submission, but may be because it included sensitive information such as personal details.