Tunable spatial heterogeneity in structure and composition within aqueous microfluidic droplets

• Main Authors: Hui, Sophia Lee Su (Contributor), Wang, Pengzhi (Author), Kun Yap, Swee (Author), Khan, Saif A. (Contributor), Hatton, Trevor Alan (Author)
• Other Authors: Massachusetts Institute of Technology. Department of Chemical Engineering (Contributor), Singapore-MIT Alliance in Research and Technology (SMART) (Contributor), Hatton, T. Alan (Contributor)
• Format: Article
• Language: English
• Published: American Institute of Physics, 2013-06-21T15:23:05Z.
• Subjects: Article
• Online Access: Get fulltext

 In this paper, we demonstrate biphasic microfluidic droplets with broadly tunable internal structures, from simple near-equilibrium drop-in-drop morphologies to complex yet uniform non-equilibrium steady-state structures. The droplets contain an aqueous mixture of poly(ethylene glycol) (PEG) and dextran and are dispensed into an immiscible oil in a microfluidic T-junction device. Above a certain well-defined threshold droplet speed, the inner dextran-rich phase is "stirred" within the outer PEG-rich phase. The stirred polymer mixture is observed to exhibit a near continuum of speed and composition-dependent phase morphologies. There is increasing interest in the use of such aqueous two-phase systems in microfluidic devices for biomolecular applications in a variety of contexts. Our work presents a method to go beyond equilibrium phase morphologies in generating microfluidic "multiple" emulsions and at the same time raises the possibility of biochemical experimentation in benign yet complex biomimetic milieus.