Scientists have made a highly sensitive molecular sensor from graphene

Despite the enormous potential of such unique material as graphene, there are not very many practical applications for it yet. Scientists from the Federal Polytechnic School of Lausanne (France), together with researchers from the Institute of Photon Research (Spain), made a graphene-based sensor . This sensor has a high sensitivity, and it can be configured to search for a specific type of molecule.

The sensor uses the well-known principle of infrared atomic absorption spectroscopy. This method allows one to study the energy states of quantum systems by studying the absorption spectra of electromagnetic radiation. The radiation of the continuous spectrum is transmitted through a layer of matter, and a part of it is absorbed. In this case, waves with lengths characteristic of the energy states of the test substance are absorbed.
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Usually, light is used for this - but since the infrared photon has a wavelength of 6 micrometers, and the molecules are several nanometers in size, it is very difficult to detect individual molecules by this method. But graphene of the desired geometry is able to focus the light on the desired area and pick up the corresponding vibrations of the molecule connected to it.

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

Moreover, this method allows 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 specific bonds. For this, the graphene sensor is “tuned” to these oscillations by applying to it an electrical voltage of various sizes. As a result, it becomes possible to obtain complete information about the molecule under study. Scientists have tested this method on protein molecules and obtained an exhaustive description of their structures.



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