Electrohydrodynamic-Driven Micromixing for the Synthesis of Highly Monodisperse Nanoscale Liposomes

Microfluidic-based chemical synthesis is uniquely suited for the fabrication of reproducible and monodisperse nanoparticle batches due to the highly controlled reaction environments in microscale dimensions. With many passive and active micromixers emerging for the on-chip chemical synthesis needs, electrically driven fluid actuation is yet an unexplored technique with much-unrealized potentials. Accordingly, in this study, we propose a micromixer based on electrohydrodynamic-driven fluid instabilities for the synthesis of liposomes using the nanoprecipitation principle. The mixing channel embeds microelectrodes to impose a transverse electric field upon coflowing reagent-containing solvent and antisolvent streams. The sharp discontinuity in electrical parameters of solvent and antisolvent solutions at their interfaces is the source of fluid motion when low AC voltages are applied to the electrodes. The fluid instabilities at the interfaces lead to efficient mixing and nanoprecipitation of nanoparticles producing highly monodisperse liposomes for the unprecedented flow rates up to 400 μL/min and small voltages up to 10 V_pp compared to its counterpart active micromixers. The liposome characteristics were studied by systematically evaluating the flow parameters, initial lipid concentrations, and surface charge. The obtained results and the working mechanism of the proposed micromixer can readily be extended to the production of nanoparticles of different chemistries relying on mixing of biphasic liquids.