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Surfactant-free silver nanofluids as liquid systems with neuromorphic potential
Nikitin, D. ; Biliak, K. ; Lemke, J. ; Protsak, M. ; Pleskunov, P. ; Tosca, M. ; Ali-Ogly, S. ; Červenková, V. ; Adejube, B. ; Bajtošová, L. ; Černochová, Zulfiya ; Prokeš, J. ; Křivka, I. ; Biederman, H. ; Faupel, F. ; Vahl, A. ; Choukourov, A.
Neuromorphic engineering is a rapidly developing branch of science that aims to implement the unique attributes of biological neural networks in artificial devices. Most neuromorphic devices are based on the resistive switching effect, which involves changing the device’s conductivity in response to an external electric field. For instance, percolating nanoparticle (NP) networks produced by gas aggregation cluster sources (GAS) show collective spiking behavior in conductivity reminiscent of brain-like dynamics. Nevertheless, the problem of dynamic spatial reconfiguration in solid-state neuromorphic systems remains unsolved. Herein, novel nanofluids with resistive switching properties are proposed as neuromorphic media. They are produced by depositing silver NPs from GAS into vacuum-compatible liquids (paraffin, silicon oil, and PEG) without the use of surfactants or other chemicals. When the electric field is applied between two electrodes, the migration of NPs toward biased electrode is detected in all liquids. The electrophoretic nature of the NP movement was proved by means of ζ-potential measurements. Such movement led to the self-assembly of NPs in conductive paths connecting the electrodes and, as a result, to resistive switching. The electrical response was strongly dependent on the dielectric constant of the base liquid. The Ag-PEG nanofluid demonstrated the best switching performance reproducible during several tens of current-voltage cycles. The growth of flexible and reconfigurable conductive filaments in nanofluids makes them suitable media for potential realization of 3D neural networks.
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Low temperature plasma and nanoparticles: effects of gas flow and surfaces
Ali-Ogly, Suren ; Kousal, Jaroslav (advisor) ; Blažek, Josef (referee) ; Kudrna, Pavel (referee)
Title: Low temperature plasma and nanoparticles: effects of gas flow and surfaces Author: Ing. Suren A. Ali-Ogly, B.Eng Department / Institute: Department of Macromolecular Physics / Charles University Supervisor of the doctoral thesis: Mgr. Jaroslav Kousal, PhD, Department of Macromolecular Physics / Charles University Abstract: This PhD thesis investigates the role of carrier gas flow in the magnetron-based gas aggregation cluster source and its impact on nanoparticle transportation. The research encompasses both theoretical and experimental aspects of low-temperature plasma interaction with surfaces and material engineering applications. Numerical models and computational fluid dynamics simulations are employed to understand the underlying physics of nanoparticles motion in gas aggregation cluster sources. The study demonstrates that carrier gas flow, particularly its velocity and inlet configuration, significantly influences the nanoparticles trap region and their residence time in the plasma. Brownian diffusion is identified as a critical factor affecting the spatial behaviour of NPs, contributing to both their escape and loss in gas aggregation cluster sources. The deposition of thin films using magnetron sputtering of PLA, a promising polymer material, is shown to facilitate nanoparticle adhesion....
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