Dynamic Behavior of Gas Bubbles and Droplets in a Magnetic Liquid in Microfluidic Chips of Various Configuration in an Inhomogeneous Magnetic Field

Purpose. To investigate the dynamic behavior of gas bubbles and droplets in a magnetic liquid in microfluidic chips of various configurations in an inhomogeneous magnetic field.

Methods. The study was carried out on an experimental setup for studying multiphase systems in microchannels, developed on the basis of known methods. An annular permanent magnet was used as a magnetic field source, and a two-channel syringe pump made from a 3D printer assembly kit was used to supply liquids to the microfluidic chip. The dynamics of drop and bubble flows was recorded using an optical microscope. Microfluidic devices are made in two ways: based on sandwich structures with Parafilm film and using ESCARGOT technology.

Results. The paper presents an experimental setup for the study of multiphase systems in microchannels. A number of experiments have been carried out in which the hydrodynamics and hydroaerodynamics of various non-magnetic and magnetic fluids in microfluidic chips are investigated. It is shown how the wettability of the walls of microfluidic devices affects the formation of droplets in the channel. The results of the study of the dependence of the size of nonmagnetic inclusions on the change in the magnetic fluid flow rate showed that the volume of generated water droplets decreases due to an increase in the continuous phase flow rate or an increase in the magnetic field strength acting on a magnetic multiphase system.

Conclusion. During the experiment, it was found that the formation of droplets in the channel was best traced in chips based on a silicone compound, where mineral or synthetic oils were the continuous medium. It was determined that the size and surface of the microchannel also influences the formation of emulsions in microchannels. The chosen chip configuration (flow focusing) is optimal for studying non-magnetic inclusions in MF, therefore, this type of microfluidic devices will be more promising for further studies of droplet hydrodynamics in microfluidic systems.

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