Applications of Magneto Electrochemistry and Magnetohydrodynamics in Microfluidics

Abstract

Magnetic fields affect electrolytes in diverse ways. This paper focuses on the interactions among electric, magnetic, and flow fields and the applications of the resulting phenomena in microfluidics. When an electrical current is transmitted in an electrolyte in the presence of an external magnetic field, a Lorentz body force results, which may induce pressure gradients and fluid motion—magnetohydrodynamics (MHD). The resulting advection is used to pump fluids, induce/suppress flow instabilities, and control mass transfer in diverse electrochemical processes. When an electrolyte flows in the presence of a magnetic field, electromotive force (emf) is induced in the electrolyte and can be used for flow metering, hydrogen production, and energy conversion. This review describes the governing equations for modeling MHD flows in electrolytes and MHD phenomena and applications relevant to microfluidic systems, such as the use of MHD to pump and stir fluids, propel swimmers, and control fluid flow in fluidic networks without any mechanical components. The paper also briefly assesses the impact of magnetic resonance imaging (MRI) on blood flow. MHD in electrolytes is a highly interdisciplinary, combining electrokinetics, fluid mechanics, electrochemistry, and Maxwell equations.