Scientists make graphene a highly sensitive molecular sensor



    Despite the enormous potential of such a unique material as graphene, not so many practical applications have yet been created for it. Scientists from the Federal Polytechnic School of Lausanne (France), together with researchers from the Institute for Photonic Research (Spain), made a sensor based on graphene . This sensor is highly sensitive and can be configured to search for a specific type of molecule.

    In sensor operationThe well-known principle of infrared atomic absorption spectroscopy is used. This method allows one to study the energy states of quantum systems by studying the absorption spectra of electromagnetic radiation. Continuous spectrum radiation is passed through a layer of matter, and part of it is absorbed. In this case, waves with wavelengths characteristic of the energy states of the substance under study are absorbed.

    Usually light is used for this - but since the wavelength of the infrared photon is 6 micrometers and the molecules are several nanometers in size, it is very difficult to detect individual molecules using this method. But graphene of the desired geometry is able to focus the light on the desired site and capture the corresponding vibrations of the molecule connected to it.

    “First, we build nanostructures on the surface of graphene, bombarding it with electrons and etching with oxygen ions,” explains Daniel Rodrigo, co-author of the work. - In response to the incoming light, the electrons in the graphene nanostructures begin to oscillate. This effect, called localized surface plasmon resonance, allows you to concentrate light at small points, comparable in size to the desired molecules. "

    Moreover, this method allows us to determine not only the molecule itself, but also the composition of the bonds between its atoms. Different molecules emit different sets of vibrations, each of which is characteristic of certain bonds. For this, the graphene sensor is “tuned” to these oscillations by supplying it with an electric voltage of various sizes. As a result, it becomes possible to obtain complete information about the studied molecule. Scientists tested this method on protein molecules and received an exhaustive description of their structures.

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    Such a sensor allows for complex molecular analysis of a substance with just one device. However, it does not destroy the studied material. The potential of such sensors is huge - with its help it is possible to study not only proteins, but also polymers and other substances.

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