Droplet microfluidics with a nanoemulsion continuous phase.
We present the first study of a novel, generalizable method that uses a water-in-oil nanoemulsion as the continuous phase to generate uniform aqueous micro-droplets in a capillary-based microfluidic system. We first study the droplet generation mechanism in this system and compare it to the more conventional case where a simple oil/solvent (with surfactant) is used as the continuous phase. Next, we present two versatile methods - adding demulsifying chemicals and heat treatment - to allow active online chemical interaction between the continuous and dispersed phases. These methods allow each generated micro-droplet to act as a well-mixed micro-reactor with walls that are 'permeable' to the nanoemulsion droplets and their contents. Finally, we demonstrate an application of this system in the fabrication of uniform hydrogel (alginate) micro-beads with control over particle properties such as size and swelling. Our work expands the toolbox of droplet-based microfluidics, enabling new opportunities and applications involving active colloidal continuous phases carrying chemical payloads, both in advanced materials synthesis and droplet-based screening and diagnostic methods.
Department of Chemical Engineering, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, MA 02139, USA. tahatton@mit.edu.
Tonghan
T
Gu
National University of Singapore, Department of Chemical and Bimolecular Engineering, 4 Engineering Drive 4 E5-02-28, 117576 Singapore. saifkhan@nus.edu.sg.
Eunice W Q
EW
Yeap
National University of Singapore, Department of Chemical and Bimolecular Engineering, 4 Engineering Drive 4 E5-02-28, 117576 Singapore. saifkhan@nus.edu.sg.
Ambika
A
Somasundar
Department of Chemical Engineering, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, MA 02139, USA. tahatton@mit.edu.
Ran
R
Chen
Department of Chemical Engineering, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, MA 02139, USA. tahatton@mit.edu.
T Alan
TA
Hatton
National University of Singapore, Department of Chemical and Bimolecular Engineering, 4 Engineering Drive 4 E5-02-28, 117576 Singapore. saifkhan@nus.edu.sg.
Saif A
SA
Khan