ELOS 2023

Oleg Gradov

Oleg Gradov, Speaker at Optics Conferences
FRCCP RAS, Russian Federation
Title : Externally controlled autowave reaction-diffusion structures in soft matter media and labyrinth instability patterns of ferrofluids as dynamic grooves for open microfluidic / optofluidic chips with variable geometry on the lens-less holographic detector


It is proposed to use externally controlled autowave reaction-diffusion patterns in partially ordered active media and labyrinth instability patterns of ferromagnetic fluids as dynamic grooves for open fluid chips with variable geometry. The modulation of autowaves and oscillatory fronts in the active medium can be carried out optically, similarly to the case for the Belousov-Zhabotinsky reaction in the Kuhnert modification or in the reaction-diffusion processor, on the same chemical basis. If we are talking about partially ordered microheterogeneous systems with high magnetic susceptibility (such as ferromagnetic fluids, sometimes called "liquid superparamagnets" or "superparamagnetic colloids"), then it is obvious that the control of the groove morphology in them in the absence of additional sensitizers is practically possible only with the help of magnetic field (it is possible to combine instabilities with different spatial localization, achievable due to the position-sensitive detection of the magnetic field by the medium from combined sources, including multipole ones; for example, combining forms with planar-thin-layer localization, such as labyrinth instability, and Rosensweig instability or normally directed field, which is identical, in an open volume). However, it is possible to use the intrinsic photochemical properties of some components of the ferrofluid if a reaction occurs in the grooves with diffusion of the ferrofluid components on the walls of the grooves formed by it, leading to phase transitions with a change in the optical and magnetic properties simultaneously (as in models using iron-containing particles of Granik and similar), and also - the use of photosensitization methods, that is, the introduction of an external light-sensitive component into a liquid stabilizing ferromagnetic or ferrimagnetic particles (or grafting it onto the latter). In this case, the transition of Rosensweig ferrohydrodynamics / ferro(micro)fluidics (as a method of controlling a liquid using a magnetic field) to photo-ferrohydrodynamics / photo-ferrofluidics (where control without using an external optical signal does not lead to morphogenesis, which leads to control using a reaction-diffusion system of optically controlled processes, emergently colocalized with a magnetically controlled environment).


Oleg V. Gradov is the Senior Researcher at the Semenov Institute of Chemical Physics (Russian Academy of Sciences, Moscow), working in the Department of Chemical and Biological Processes Dynamics (CHEMBIO). He is the author of ≈ 200 journal papers. His recent grants include: “Development of the novel physical methods for complex biomedical diagnostics based on position-sensitive mapping with the angular resolution at the tissue and cellular levels using analytical labs-on-a-chip” (RFBR 16-32-00914) and “Lab-on-a-chip development for personalized diagnostics” (FASIE 0019125), "Ferroelectric polymers for biomedical engineering" (RFBR 20-12-50344). He is also an ambassador of “ASAPBio”* (Accelerating Science and Publication in Biology, based in Cambridge, USA).