Magnetic particle mixing with magnetic micro-convection for microfluidics

• We study the magnetic micro-convection as a mixing method in microfluidics.
• We show that the method enhances mixing with magnetic field squared dependency.
• We propose a flow cell setup for mixing and justify it with a sample experiment.
• The mixing method can be easily implemented in an existing microfluidics setup.

In this paper we discuss the magnetic micro-convection phenomenon as a tool for mixing enhancement in microfluidics systems in cases when one of the miscible fluids is a magnetic particle colloid. A system of a water-based magnetic fluid and water is investigated experimentally under homogeneous magnetic field in a Hele–Shaw cell. Subsequent image analysis both qualitatively and quantitatively reveals the high enhancement of mixing efficiency provided by this method. The mixing efficiency dependence on the magnetic field and the physical limits is discussed. A suitable model for a continuous-flow microfluidics setup for mixing with magnetic micro-convection is also proposed and justified with an experiment. In addition, possible applications in improving the speed of ferrohydrodynamic sorting and magnetic label or selected tracer mixing in lab on a chip systems are noted.