Issue 9, 2018

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

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

Supplementary files

Article information

Article type
Paper
Submitted
31 Jan 2018
Accepted
28 Mar 2018
First published
28 Mar 2018
This article is Open Access
Creative Commons BY license

Lab Chip, 2018,18, 1330-1340

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

This article is licensed under a Creative Commons Attribution 3.0 Unported Licence. You can use material from this article in other publications without requesting further permissions from the RSC, provided that the correct acknowledgement is given.

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