Hydrodynamic influence on magnetic microsphere capture in a microfluidic liquid–liquid micro-extraction system: An analytical modeling

In micro-total analytical systems, magnetic microspheres are frequently utilized to separate bio-entities in various bio-micro electro mechanical systems. In a liquid–liquid micro-extraction system an aqueous suspension of the magnetic particle-analyte conjugate can be extracted from the carrier to a non-carrier solution. However, the extraction process is extremely sensitive to the smallest change in the magnetic or hydrodynamic parameters. Here, an analytical model for the magnetophoretic transport and capture of micro-particles in a typical aqueous two-phase system is proposed. The system involves the flow of immiscible aqueous solutions of polyethylene glycol and dextran. For a certain geometry and magnetic arrangement, the effect of the flow rates, viscosities, fluid residence time, particle and fluid Reynolds numbers on the particle movement and capture are investigated. The impact of an intuitively considered group parameter K * on capture efficiency (CE) is noticed. The results obtained from the study confirm that there is a momentous impact of fluidic parameters of the two aqueous phases on the extraction of the particles.