Flow invariant droplet formation for stable parallel microreactors

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.

The upcoming 3D-printing revolution in microfluidics

“…Inspired by the Lego ® bricks concept, functional and modular elements of a complex microfluidic circuit, have been printed by SL, and assembled by a “plug-and-play” interlocking mechanism, into a complete microfluidic device 141-145 (Figure 12). A tunable microfluidic mixer and a droplet generator are examples of complex microfluidic devices that have been demonstrated by assembling SL-printed discrete functional modules 143,146 (Figure 12E-H). …”

How Size Determines the Value of Gold: Economic Aspects of Wet Chemical and Laser‐Based Metal Colloid Synthesis

“…Besides the variation of laser parameters, [29,40,41] such as pulse energy,l aser wavelength, pulse widthsa nd repetition rate, the target geometry can be optimized from thin gold foils to wires [42,43,44] as well as reconstruction of the batch ablation chamber to ac ontinuously workingf low chamber. [47,48] It was shown, that the use of droplet microfluidic reactors can increaset he platinum nanoparticley ield by af actor of 2c ompared to conventional batch synthesis. Furthermore,e ven cheaper laser systems with higherl aser power corresponding to higher nanoparticle productivities will be availablei nt he near future,i ft he trend in laser technology remains.…”

“…[37,45] In addition, the change of the target geometry and operation mode improves the reproducibility of gold nanoparticle synthesis. [48] In addition, not only the automation and nanoparticle productivity can be enhanced, but also the reproducibility and particle quality in contrast to batch synthesis. [46] While the decreasei na bsolutec osts forl aser-based nanoparticle synthesis is enabledb yc hoosing laser sources with ah igherp ower, reduction of costs fort he wet-chemical nanoparticle synthesis can be achieved by an increase of the rotor capacity used for ultracentrifugation over the standard value of 120 mL.…”

“…Furthermore,e ven cheaper laser systems with higherl aser power corresponding to higher nanoparticle productivities will be availablei nt he near future,i ft he trend in laser technology remains. [48] Consequently,f or ab atch size of 1g an enhancement of nanoparticle productivity ends up in as ignificant cost reduction for both nanoparticle synthesis methods on an industrial scale. The increase of liquid capacity per centrifuge passage towards 1500 mL results in nanoparticle net productivityi ncreasef rom 35 mg h À1 towards 850 mg h À1 at ag old concentrationo f 800 mg L À1 (Figure 6b).…”

Droplet microfluidics: A tool for biology, chemistry and nanotechnology

“…In contrast, droplet generation in the gradient-confinement method does not depend on flow conditions. Recently, a combined strategy was introduced which includes parallelized 3D generators and principles based on gradient confinement [15]. Developments in dropletgeneration technologies are fundamental to the development and application of droplet-based approaches.…”