Magnetohydrodynamic Microfluidic Drive of Ionic Liquids

Ionic liquids are increasingly attracting the attention of researchers in both academia and industry. However, research into ionic liquids is mainly limited in chemistry, and the electromagnetic characteristics and microfluidic/optofluidic applications of ionic liquids have been rarely studied. Here, ionic liquids are used as a new type of fluid material for microfluidics/optofluidics, and the research on magnetohydrodynamic (MHD) microfluidic drive of ionic liquids is conducted using hydrophilic [bmim]BF₄ and hydrophobic [bmim]NTf₂. The experimental study shows that ionic liquids can be driven by Lorentz force to induce laminar flow. The flow rates of [bmim]NTf₂ are 2.7 and 7.8 μl/s at applied direct-current potentials of 6 and 8 V, respectively, in a 0.4-T magnetic field. The experimental results of the two ionic liquids and electrolytes are compared. Moreover, the experimental results are compared with the theoretical data calculated using a numerical simulation and Poiseuille´s law, and the limitation of Poiseuille´s law is pointed for the MHD drive. The conducted research can promote the application of ionic liquids in microfluidics or optofluidics.