Citation: Yuskina, E.; Makarov, N.; Khaydukova, M.; Semenov, V.; Panchuk, V.; Kirsanov, D. Sensor Device for Contactless Chemical Analysis Based on High-Frequency Inductance Coil. Eng. Proc. 2023, 48, 42. https://doi.org/10.3390/ CSAC2023-14886 Academic Editor: Nicole Jaffrezic-Renault Published: 18 September 2023 Copyright: © 2023 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https:// creativecommons.org/licenses/by/ 4.0/). Proceeding Paper Sensor Device for Contactless Chemical Analysis Based on High-Frequency Inductance Coil † Ekaterina Yuskina 1 , Nikodim Makarov 1 , Maria Khaydukova 2,3 , Valentin Semenov 1,4 , Vitaly Panchuk 1,4 and Dmitry Kirsanov 1, * 1 Institute of Chemistry, St. Petersburg University, 198504 St. Petersburg, Russia; yuskina.k@yandex.ru (E.Y.) 2 Laboratory of Alternative Antimicrobial Biopreparations, World-Class Research Center “Center for Personalized Medicine”, FSBSI Institute of Experimental Medicine, 197376 St. Petersburg, Russia 3 Laboratory of Peptide Chemistry, Institute of Human Hygiene, Occupational Pathology and Ecology, 188663 St. Petersburg, Russia 4 Institute for Analytical Instrumentation RAS, 198095 St. Petersburg, Russia * Correspondence: d.kirsanov@gmail.com; Tel.: +7-921-333-1246 † Presented at the 2nd International Electronic Conference on Chemical Sensors and Analytical Chemistry, 16–30 September 2023; Available online: https://csac2023.sciforum.net/. Abstract: In this work, we explore the analytical potential of a simple inexpensive sensor device based on the evolution of the high-frequency contactless conductometry method. This method was developed in the middle of the 20th century as one of the options to assess the electrical conductivity of samples, and it employed electrical signals registered at a specific, single AC frequency. The method did not find a wide application since the analytical signal in the developed systems was a complex function of many factors (sample conductivity, capacitive characteristics, dielectric permittivity, and magnetic properties), which was difficult to be mathematically processed. We came back to this technology with the following in mind: (1) modern electronic components enable the design of such measuring devices in a very-low-cost manner and allow registering the response signal in a whole range of AC frequencies; (2) the application of modern machine learning tools to process these signals allows for the extraction of qualitative and quantitative information about the samples. It was found that the detector has numerous capabilities such as the quantification of inorganic salts in individual aqueous solutions and in complex mixtures, the quantification of dielectric constants of organic solvents, and distinguishing the cultures of various bacteria and cancer cells. Keywords: electromagnetic sensor; non contact; high frequency; conductometry 1. Introduction An urgent task of modern analytical chemistry is the development of simple and inex- pensive devices for the analysis of real objects in non-laboratory conditions. Such devices are in demand in the chemical control of technological process, in environmental monitor- ing, and for the detection of drugs or explosive substances. In this way, the methods that allow for contactless and on-line analysis are preferred. A promising direction is the search for physical principles, initially oriented towards the creation of simple and inexpensive devices through electrical measurements. A high-frequency, non-contact conductometry method was developed in the middle of the 20th century [1]. The devices operate in the megahertz frequency region; the sensor response is recorded at one particular frequency. When the electrical signal is registered in the high-frequency region, the sensor response depends not only on the conductivity of the solution, as the classical conductometry does. The registered electrical signal depends, in a complex way, on the sample conductivity, dielectric constant, magnetic properties, and capacitance in the high-frequency contactless conductometry method. Thus, such devices are only applicable for conductometric titration, Eng. Proc. 2023, 48, 42. https://doi.org/10.3390/CSAC2023-14886 https://www.mdpi.com/journal/engproc