Scientists from the UPC investigate reconfigurable and programmable metamaterials


Metamaterials are applied in the design of antennas, radars and imaging systems for medical applications


The function of a nanomaterial can be modified from an external device (in this case, a tablet)


From left to right: researchers Eduard Alarcón, Sergi Abadal —holding a tablet in his hands showing the logo of the project and a simulation that is being worked on—and Albert Cabellos.

Creating materials with programmable electromagnetic properties, called software-defined reconfigurable metamaterials, is the goal of the scientists working on the European VISORSURF project, in which the interdepartmental group NaNoNetworking Center in Catalonia (N3Cat) of the UPC participates. It is seen as a revolutionary technology with multiple applications in electronics, medicine, photovoltaic solar energy, optics and other uses that are as yet unimaginable.

Jul 10, 2017

The VISORSURF project, which will receive funding from the European Commission to the tune of €6 million over three and a half years, is part of the European FET OPEN programme, an ambitious plan within Horizon 2020 that focuses on frontier research and has great potential for devising radically new technologies.

A metamaterial is an artificial structure that is specifically designed to obtain a behaviour or physical property that cannot be obtained with a natural material or, in fact, in any other way. In electromagnetism, for example, metamaterials can be created to manipulate the reflection of light or other waves from or in specific directions. They are applied in the design of antennas, radars and imaging systems for medical applications.

Scientists are now trying to obtain a metamaterial whose properties can be selected from a few options using a simple application running on an electronic device such as a tablet. Once the properties have been selected, the device sends appropriate instructions to the metamaterial so that its internal network interprets the instructions and modifies the metamaterial’s behaviour and gives it the chosen properties. The process can be repeated as many times as needed.

To meet the challenge, the VISORSURF project has brought together an interdisciplinary team of physicists, experts in materials science, electronic engineers, telecommunications engineers and computer scientists in a consortium of six European institutions: the Universitat Politècnica de Catalunya (UPC), Aalto University in Finland, the Foundation for Research and Technology in Greece, the University of Cyprus, the Fraunhofer-Institut für Zuverlässigkeit und Mikrointegration (IZM) in Germany and SignalGenerix in Cyprus.

Overcoming current limits for unimaginable applications
The main drawback that metamaterials currently have is that their design is very specific and static.They can only be applied to the problem for which they were designed, and their behaviour cannot be reused or changed. The aim from now on must be to overcome these limitations and to design reconfigurable and programmable metamaterials whose behaviour can be changed over time in a controlled manner, thus making them reusable and suited to many more applications, some of which are yet to be discovered.

One of the project’s challenges is therefore to be able to easily program the materials’ functions. To this end, scientists are working on creating a layer of software that allows the desired function to be easily defined. This layer is responsible for translating functionality into specific operations, which are distributed through the network installed within the metamaterial until they reach the nanoprocessors, which eventually modify the internal structure of the metamaterial to achieve the desired behaviour. This will favour the use of reconfigurable metamaterials and encourage research into new and disruptive uses of this technology. These systems can even become "invisible" objects if certain conditions are met, such as covering them to prevent electromagnetic waves bouncing off them.

To make all of this possible, a network of sensors and nanoprocessors is necessary inside the metamaterial to allow its properties to be controlled at a very fine resolution: 1 cm for Wi-Fi waves 50 nanometres for light. In the future, these achievements may open the door to the reconfigurable manipulation of light.

The research group NaNoNetworking Center in Catalonia (N3Cat) led by Sergi Abadal, Eduard Alarcón and Albert Cabellos studies what these networks might be like, which is the only way to change the metamaterial’s behaviour. They design the network that connects the nanoprocessors that modify the metamaterial’s behaviour. Their study covers many aspects of telecommunications engineering and network design in a new environment that has never been analysed until now. Whether a metamaterial can be truly reconfigurable depends on the study’s success.

In addition to numerous electronic and medical applications, the new metamaterials will be of great interest in the field of the seismology to modify the waves of an earthquake when they come into contact with buildings, preventing the vibrations and aftershocks that can make them collapse. They will also be of use in the renewable energies sector to improve photovoltaic panels so that they absorb the maximum amount of solar radiation, and will be useful in optics as filters and in sound to improve the installation of sound systems.

The diagram below shows how the function of a nanomaterial can be modified from an external device (in this case, a tablet), thanks to the orders received by the built-in drivers in the metamaterial. In the example, the nanomaterial performed the function of absorbing green and is modified to absorb red instead of green.