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Issue 9, 2018
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Electrically controlled mass transport into microfluidic droplets from nanodroplet carriers with application in controlled nanoparticle flow synthesis

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Abstract

Microfluidic droplets have been applied extensively as reaction vessels in a wide variety of chemical and biological applications. Typically, once the droplets are formed in a flow channel, it is a challenge to add new chemicals to the droplets for subsequent reactions in applications involving multiple processing steps. Here, we present a novel and versatile method that employs a high strength alternating electrical field to tunably transfer chemicals into microfluidic droplets using nanodroplets as chemical carriers. We show that the use of both continuous and cyclic burst square wave signals enables extremely sensitive control over the total amount of chemical added and, equally importantly, the rate of addition of the chemical from the nanodroplet carriers to the microfluidic droplets. An a priori theoretical model was developed to model the mass transport process under the convection-controlled scenario and compared with experimental results. We demonstrate an application of this method in the controlled preparation of gold nanoparticles by reducing chloroauric acid pre-loaded in microfluidic droplets with L-ascorbic acid supplied from miniemulsion nanodroplets. Under different field strengths, L-ascorbic acid is supplied in controllable quantities and addition rates, rendering the particle size and size distribution tunable. Finally, this method also enables multistep synthesis by the stepwise supply of miniemulsions containing different chemical species. We highlight this with a first report of a three-step Au–Pd core–shell nanoparticle synthesis under continuous flow conditions.

Graphical abstract: Electrically controlled mass transport into microfluidic droplets from nanodroplet carriers with application in controlled nanoparticle flow synthesis

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Publication details

The article was received on 31 Jan 2018, accepted on 28 Mar 2018 and first published on 28 Mar 2018


Article type: Paper
DOI: 10.1039/C8LC00114F
Citation: Lab Chip, 2018,18, 1330-1340
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    Electrically controlled mass transport into microfluidic droplets from nanodroplet carriers with application in controlled nanoparticle flow synthesis

    T. Gu, C. Zheng, F. He, Y. Zhang, S. A. Khan and T. A. Hatton, Lab Chip, 2018, 18, 1330
    DOI: 10.1039/C8LC00114F

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