Study of Electrokinetic Possibilities of Bacteria (S.aureus) Separation and Concentration by Developed Four-electrode Biosensor Chip Formats with ITO Microelectrodes in Whole Blood

Abstract

The electrokinetic possibilities of separation and concentration of S.aureus bacteria in human whole blood (test mixture) were studied using a new design of a four-electrode biosensor chip format with transparent microelectrodes. In the measurements, a closed cell was used, into which the test mixture was poured. The electrokinetic movement of bacteria during concentration was observed when AC voltage was applied to the first and second annular external electrodes, and DC voltage was applied to the third and fourth semicircular central electrodes. The process of separation of erythrocytes and concentration of bacteria was recorded by an optical method. It is shown that the concentration of bacteria appears after 8 minutes and increases by 30 minutes in the region of the central electrodes under model conditions. The measurements were carried out on two biosensor chip formats having almost identical electrophysical parameters of capacitance and conductivity at frequencies from 100 Hz to 1 MHz. It is determined that the amplitude-frequency mode and biosensor chip format can be used to develop methodological support for the identification of bacterial species, but only by optical methods. It is shown that in order to increase the number of bacteria on both of the central electrode in the concentration mode, it is necessary to increase the speed of the electroosmotic flow at alternating current, by optimizing the composition of the medium and the parameters of the electrical regime in order to equalize the rates of separation and concentration processes.