Experimental and Computational Analysis of Mixing Inside Droplets for Microfluidic Fabrication of Gold Nanoparticles

Emulsions formed by mixing reactant streams inside microdroplets are efficient microscale reactors for the synthesis of nano/microparticles/crystals due to small quantities reagents confined within each droplet and separation contents from reactor walls. In this work, size-tunable gold nanoparticles (AuNPs) emulsion droplets generated in a three-phase glass capillary microfluidic device was investigated experimentally numerically using computational fluid dynamics (CFD). AuNPs were produced micromixing two aqueous streams, 1.15 mM HAuCl4 containing 1% poly(vinylpyrrolidone) capping agent 20 ascorbic acid solutions, monodispersed created three-dimensional (3D) counter-current flow focusing medium-chain triglyceride. The mean particle size tunable range between 26 56 nm depended on degree premixing shortly before generation, efficiency droplets, which controlled hydrodynamic conditions device. CFD results compared validated against experimental observations revealed presence recirculation zone near outer wall injection tip. higher at smaller causing reduction AuNPs.