Mixing Dynamics and Synthesis Performance of Staggered Herringbone Micromixer for Limit Size Lipid Nanoparticles

Staggered herringbone micromixer has shown good efficiency of mixing and performance of synthesizing nanoparticles. To bring a detailed understanding of the mixing dynamics and synthesis performance of this kind of micromixer, this paper carries out a high-fidelity numerical simulation and a parametrial experimental study on a well-established design. A passive tracer is induced in the numerical simulation to analyze mixing dynamics induced by the staggered herringbone structures. Three effects are identified to reveal the underlying mechanisms, including folding, stretching, and splitting. To the authors' knowledge, the splitting effect is identified for the first time by the isosurface of the passive tracer, to show the high efficiency of the staggered herringbone design. The micromixer is then used to synthesize lipid nanoparticles by mixing a mixture of lipid and poly (lactic-co-glycolic acid) (PLGA) solutions with deionized water. Under a wide mass ratio of lipid and PLGA solutions, nanoparticles with good monodispersity are synthesized to reflect the good compatibility of the micromixer and the mixture. In addition, an optimized mass ratio is identified from the parametrical experiment.