Title: Characterization of slug flow of two aqueous phases by electrochemical impedance spectroscopy in a fluidic chip
Authors: Polezhaev, Petr
Slouka, Zdeněk
Lindner, Jiří
Přibyl, Michal
Citation: POLEZHAEV, P. SLOUKA, Z. LINDNER, J. PŘIBYL, M. Characterization of slug flow of two aqueous phases by electrochemical impedance spectroscopy in a fluidic chip. MICROELECTRONIC ENGINEERING, 2018, roč. 194, č. JUL 5 2018, s. 89-95. ISSN: 0167-9317
Issue Date: 2018
Publisher: Elsevier
Document type: článek
URI: 2-s2.0-85044131761
ISSN: 0167-9317
Keywords in different language: impedance spectroscopy;aqueous two-phase systems;ATPS;microfluidics;film thickness
Abstract in different language: We adopted a method of electrochemical impedance spectroscopy (EIS) for the characterization of slug flow of two immiscible aqueous phases in a flow channel. The impedance response (both magnitude and phase shift) of the two-phase system is measured as a function of time at selected frequencies. The presence of slugs or a continuous phase at a pair of parallel facing electrodes can be determined under various signal frequencies mainly due to a significant difference in the electrolytic conductivities of both phases. We found that EIS data are sensitive to the total flowrate at low signal frequencies. Further, we suggested an equivalent electric circuit that takes into account all capacitances and resistances emerging between the two sensing electrodes. We determined the values of these elements by fitting a theoretical model to the experimental data. The obtained values of resistances were used to estimate the thicknesses of the wall film of the continuous phase that is present between a slug of the dispersed fluid and a channel wall. The estimates given by the EIS method were successfully verified by microscopic observation and an available hydrodynamic correlation. The developed EIS method represents an original approach to the estimation of wall film thickness applicable to the efficient control of various droplet-based microfluidic devices such as microreactors and microextractors working with aqueous two-phase systems.
Rights: Plný text je přístupný v rámci univerzity přihlášeným uživatelům.
© Elsevier
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