Oleg V. Gradov

Semenov Institute of Chemical Physics-RAS, Russia

Title: Microfluidic Polarographic Catalymetry

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Biography

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. His recent works are focused on lab-on-a-chip design for multispectral multiparametric mapping, ERD-SBGN-mapping of biological samples, chemometric microspectroscopy and spectroelectrochemical electro-morphological techniques. He is the author of 150 journal papers (and >100 conference papers and reports), and an editorial board member of 10 journals. 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). He is also an ambassador of “ASAPBio”* (Accelerating Science and Publication in Biology, based in Cambridge, USA) in Russia and member of several comities (Technical Committee on Standards, IEEE, Engineering in Medicine & Biology Society; Technical Committee on Biomedical Imaging & Image Processing, IEEE, Engineering in Medicine and Biology Society; IEEE Biometrics Council**; etc.).

Abstract

Polarographic catalymetry is an analytical method where parallel to the measurements, the analyte precipitates on the platinum electrode, changing the detector parameters. To eliminate this problem, chemists often use rotating platinum electrodes and a limitation on the analysis polarity (using them only in oxidation schemes, as, in the reducing conditions, the sediment on the electrode surface is formed). In the case of using microfluidic technology that combines the properties of an analytical sensor and a microreactor, it is possible to treat sedimentation not only as a problem but also as an opportunity to introduce an adaptive manufacturing process in which the properties of the enthrakometer surface exposed to microwave radiation are controllably modified during its operation on a chip. Moreover, it is possible to create rotational sensor systems (similar to centrifugated and so-called “spin-coating-assisted” planar microfluidics) based on the rotation modes of the Pt-electrode-bearing platform in the microwave device. It is well known that platinum is widely used as a sublayer/underlayer for film deposition. Sedimentation and growth of other metals on the platinum electrode are controlled by electrochemical methods, in particular, by cyclic voltammetry, synchronously with methods based on non-electrochemical principles. As a consequence, it is possible to combine electrochemical catalymetry on platinum electrodes and microwave enthrakometric catalymetry in a single device.

Due to inertness and the corresponding activation barrier, magnetron sputtering on platinum is less effective for a number of structured films with a perovskite-like structure than for other inert substrates/carriers (300 °C for Au versus 650 °C for Pt). This is confirmed by the morphology of the films and the results of X-ray diffractometry and X-ray photoelectron spectroscopy (XPS). However, the production of piezoelectric films based on similar technologies on platinum (and platinum-coated silica) substrates, in a multilayer technique allowing one to obtain capacitors with a very high dielectric constant, makes it possible to introduce new descriptors into the analysis performed by the modified enthrakometer in situ. Its surface properties are controllably changed in the course of the ongoing analysis. The change in surface-coupled properties alters the nature of the reactivity of the enthrakometer. The above compounds with a perovskite structure obtained by the magnetron sputtering methods which can be controllably crystallized in a microwave field, are used in the design of triboelectric photodetectors (including hybrid ones with other materials), gas sensors, and non-enzymatic sensors for a number of important biochemical agents (glucose, peroxide), etc.

Despite the difference in the methods of production and technical processes in specific cases, it is possible to design an enthrakometric sensor with a complex of active properties in electrochemical processes at the microwave field. In this case, we do not consider non-chemometric applications (such as the design of mechanoelectrical transducers or acoustic sensors), but it is yet enough to confirm the possibility of on-chip implementation, in a microwave field, of multifactor chemical microanalytical techniques that require chemometric approaches to data analysis.