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Research area 02 - PHYSICS AND SPACE SCIENCES, 02-204 - Nano- and microstructures

Keywordsmetal-organic frameworks, MXenes, polymers, nanocomposites, laser processing, nanospectrocopy, electrical characterization, numerical modeling, flexible sensors, biomedicine, semiconductors, flexible electronics, lightweight materials, scalable production

Annotation
In the modern world, there is a trend towards the development of personalized medicine, which entails the need to create new sensors capable of accurately and quickly tracking the indicators of the human body. The need for such sensors, in turn, leads to the need to create and investigate new highly sensitive materials, including composites. This project is aimed at the investigation of properties promising for use in sensing materials, such as metalorganic frameworks and MXenes. In addition to the use of pure materials, it is possible to form composites based on them using laser processing. Also, laser processing, which is a universal, cheap, environmentally friendly, and scalable processing method, will allow controlling both the properties of individual materials and composites by varying the irradiation parameters (power density, wavelength, pulse duration, etc.). Eventually, we plan to get temperature and pressure sensors integrated into one device, based on composite materials.

Expected results
As a result of the project, we plan to get a series of sensors integrated into a single device, completely made by the means of laser processing of a range of materials and their combinations (including the patterning of conductive channels and contacts). Thus, this project will allow us to once again consider laser processing technology as a promising tool for the fabrication of new-generation sensors. At the same time, we will propose new highly sensitive composite materials that will significantly advance the development of personalized medicine. It is worth mentioning that as a result of the project, we will describe the fundamental aspects of the interaction of laser radiation with the materials and the correlation between the irradiation parameters and the structural changes it makes to the processed materials.

Annotation of the results obtained in 2023
The project's goal is developing multifunctional flexible sensors that do not exhibit crosstalk, where the Chinese partner prepares materials and their combinations for efficient crosstalk-free devices, while the Russian side is exploring laser processing of these materials to tune their properties and increase the durability of sensors. During the first year, the Russian side performed fundamental research into the effects of laser processing on MOFs, MXenes and other nanomaterials. We investigated the mechanism of laser processing for zeolitic imidazolate frameworks (ZIF-8), and discovered the significant photoluminescence (PL) increase under laser irradiation. Time-dependent PL measurements showed that the optical signal increased overtime and then dropped drastically. Spatial PL mapping revealed a 70-fold intensity rise and its red-shift from unirradiated to irradiated region. We demonstrated tunable PL enhancement without ablating ZIF-8 by controlling irradiation conditions. Comprehensive analysis revealed the PL enhancement by formation of laser-induced N-doped nanocarbons. Furthermore, we integrated the PL-enhanced ZIF-8/nanocarbon architectures into thermoplastic polyurethane (TPU), creating flexible electrodes with superior mechanical resilience. These electrodes survived 15 min of sonication and 10000 bending cycles without degradation of electrical properties. The laser-processed ZIF-8/TPU composites exhibited robust and consistent sensing capabilities, proving effective for human-body monitoring applications as both temperature and flexure sensors. For the MXene film, Raman spectroscopy tracked chemical changes during laser irradiation in air. High laser power caused notable TiO2 content increases. Multiple other analyses of MXenes confirmed their poor stability, with signs of oxidation observed by different methods. Therefore, we conducted the large-scale laser treatment in the inert atmosphere. As a result, we could preserve the high conductivity of MXenes and enhanced the interfacial adhesion of MXenes into the polymer substrate achieving an important project objective. Along with it, by processing different nanomaterials we were able to fabricate durable and stable conductive patterns that will be instrumental in improving the sensor durability. Overall, the investigation of laser irradiation of MOFs and MXenes has uncovered new insights into the mechanisms of their laser treatment leading to tailored luminescent nanocarbon formation, enhanced interfacial adhesion with minimal impact on the material's properties, and their applications for sensing. With further investigations we will be able to refine laser-processing technology and enhance the sensor performance.

Publications