An Electrochemical Impedance Spectroscopic Diagnostic Device for Characterization of Liquid-Liquid Systems and Phase Separation Detection in Emulsions

Rapid characterization of complex fluids, especially sensing emulsion stability, is crucial for many industrial applications, ranging from pharmaceutical industry to petroleum production. Electrochemical impedance spectroscopy (EIS) is a powerful tool for electrical characterization of such systems. In this study, a "milli-fluidic" EIS test fixture which is inexpensive, easily fabricated, yet robust, is designed and fabricated using 3D printing technology, which allows reliable experiments, and can then be disposed of after each test. The developed cell is tested using solutions, liquid-liquid mixtures, and oil-water emulsions. Frequency response analysis and equivalent circuit modeling have been performed to find the effective electrical properties of the liquids, and relate them to their physical properties, such as stability. EIS is applied to reveal the electrical behavior of emulsions during phase separation. It is found that creaming can be sensed based on permittivity decay, and capacitance-based measurements can be utilized to detect phase separation in emulsions.