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1. July 2021
The FET-OPEN call of the European Union’s Research and Innovation’s programme Horizon 2020 supports research and development projects bringing radically novel results with considerable impact on science and technology. One of the funded projects was the PETER project led by Tomáš Šikola of CEITEC BUT and bringing together researchers from the University of Stuttgart, Germany, the research institute NanoGUNE in Spain, and the company Thomas Keating Ltd. from the UK.
PETER is pushing boundaries of what we can investigate using the classic method of electron paramagnetic resonance (EPR). This method is used to study materials and samples containing unpaired electrons – for example biomarkers, charge carriers, defects, and so on. It has, however, one considerable drawback, and that is relatively low sensitivity – to get a clear signal, the material must contain a high concentration of the unpaired electrons.
PETER project introduces a new type of a spectroscopic EPR microscope using – for the first time ever – plasmonic effect in EPR. Plasmon is a quasi-particle born from the interaction of free electrons inside a metallic material with a high frequency radiation. In the vicinity of these plasmons, a very strong and localised electromagnetic field is generated, which in turn enhances the EPR signal and allows us to obtain high resolution information from a very small area.
The key part of the new instrument is a special probe for scanning microscopy (SPM) with a specially developed plasmonic structure (antenna) placed at the top. A customised system is used to move the tip across the sample, while we can study even samples with an uneven (heterogeneous) surface.
“We prepare these plasmonic structures here on CEITEC, using either electron lithography or optical lithography,” says professor Šikola. “We can use numerical method to precisely simulate the properties of the structures to reach the optimal level of EPR signal enhancement.” First results describing the use of numerical simulations and the fabrication of plasmonic antennas have been already published.
Enhanced sensitivity radically broadens the possibilities of what we can investigate using EPR. Lowering the resolution limit would, for example, establish a new discipline of “in-cell EPR” with the implementation in the tumour cell diagnostics. Similarly, we could study in detail the degradation processes in batteries, which would lead to the enhancement of battery lifetime. A whole new world of possibilities is opening also in the quickly developing field of quantum technologies.
“The prototype of our instrument is currently in Stuttgart, and we would like to offer it to the broader scientific community,” says professor Šikola. There is still a lot of tests to be carried out before the instrument is performance ready. “It’s a work for upcoming years, but we’re planning to keep developing the instrument until it’s ready for commercialisation.”
Author: Božena Čechalová