Flow invariant droplet formation for stable parallel microreactors

TLDR

Continuous‑flow chemistry requires consistent fluidic behavior, low fouling, and high throughput, and while droplet microfluidics improve control over heat and mass transfer, conventional designs still suffer from droplet size sensitivity to flow‑rate variations. The authors present a three‑dimensional droplet generator that maintains invariant droplet size despite flow‑rate fluctuations. The device employs a three‑dimensional geometry that stabilizes droplet formation against flow‑rate changes. The generator produces droplets across four orders of magnitude, enabling a parallel synthesis of platinum nanoparticles in an ionic liquid that is reproducible after solvent recycling and yields twice the product compared to batch synthesis.

Abstract

Abstract The translation of batch chemistries onto continuous flow platforms requires addressing the issues of consistent fluidic behaviour, channel fouling and high-throughput processing. Droplet microfluidic technologies reduce channel fouling and provide an improved level of control over heat and mass transfer to control reaction kinetics. However, in conventional geometries, the droplet size is sensitive to changes in flow rates. Here we report a three-dimensional droplet generating device that exhibits flow invariant behaviour and is robust to fluctuations in flow rate. In addition, the droplet generator is capable of producing droplet volumes spanning four orders of magnitude. We apply this device in a parallel network to synthesize platinum nanoparticles using an ionic liquid solvent, demonstrate reproducible synthesis after recycling the ionic liquid, and double the reaction yield compared with an analogous batch synthesis.