Sensor device for contactless chemical analysis based on high-frequency inductance coil

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 option to assess the electrical conductivity of the samples and employed electrical signal registered at a certain 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, magnetic properties), which was difficult to be mathematically processed. We came back to this technology having 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) application of modern machine learning tools to process these signals allows extraction of qualitative and quantitative information about the samples. It was found that the detector has numerous capabilities such as: quantification of inorganic salts in individual aqueous solutions and in complex mixtures; quantification of dielectric constants of organic solvents; distinguishing the cultures of various bacteria and cancer cells.