metamaterial
© National University of Science and Technology MISiS
Members of an international research team consisting of specialists from National University of Science and Technology MISIS (NUST MISIS) and the Polytechnic University of Turin have developed a model of a new metamaterial that will help boost the accuracy of optical and biomedical nano-sensors by shielding them from external radiation.

A new metamaterial for camouflaging nano-sensors is being developed under the Russian-Italian project ANASTASIA (Advanced Non-Radiating Architectures Scattering Tenuously and Sustaining Invisible Anapoles) that aims to simulate and recreate a metamaterial to make nano-objects invisible in any wave band, the MISIS press service said in a statement.

The research project's results are published in the prestigious Scientific Reports journal from Nature Publishers.

Today, scientists in various countries have gained experience in creating materials and objects that remain transparent within extremely narrow spectrum bands and which conceal objects only from certain angles. ANASTASIA project researchers are compiling the experience of creating such structures and a theory for simulating and creating the metamaterials that can conceal objects under any angle and within a broad spectrum band.

"It's actually easier to conceal a large object than a small one," said Anar Ospanova, a postgraduate student with MISIS' Super- Conducting Materials laboratory and the article's author whose statement is quoted by the press service. There are different camouflage and stealth technologies, she noted. "It is more complicated when working with nano-sized objects, including biomedical and physical needles-sensors. As a rule, nano-sensors are approximately of the same size as the objects that are being studied, so they seriously influence a given environment after they enter it. They change the environment's pressure and disperse radiation, and it becomes very difficult to discern between the specifications of the needle and the object itself. We have attempted to 'hide' radiation from nano-sensors and make them more accurate," she said.

The so-called meta-molecule consisting of four lithium-tantalate dielectric cylinders with a radius of five microns is the main element of this metamaterial that has been simulated by the research paper's authors. Dielectrics form the nano-sensor's improvised shroud and interact with radiation, creating what we call an anapole state or a non-radiating scatter system. Consequently, the object cannot be seen by the outside observer.

Scientists used a metal conductor with a 2.5-micron radius during their calculations. This conductor acted as an improvised nano-sensor with extremely high wave scatter volumes making it possible to develop the maximum possible scatter levels. The simulation was conducted in the terahertz band and between the infrared and UHF bands.

According to MISIS Assistant Professor Alexei Basharin who co-supervises the ANASTASIA project, the new metamaterial can be used in biomedicine, acting as the shroud of potassium chloride which is compatible with the human body.

"In some cases, we have to prevent an object from interacting with light, that is, during the delivery of medications at the nano-level. In the long run, we hope to create a meta-molecule where waves scattering from the object and its shroud will meet and neutralize each other and will make the object invisible in certain wave bands," Basharin noted.

During the project's next stage this fall, the researchers will create an experimental structure with these properties in laboratory conditions.