IBI-5 Seminar: Controlled ATPS droplet formation and capture using microfluidics

Hans M. Wyss

Department of Mechanical Engineering, TU Eindhoven, Eindhoven, Netherlands

Join us in person in Building 04.16, Room 2001

Abstract:

Aqueous two-phase systems (ATPS) are instrumental in a broad spectrum of applications, including chemical reactions, cell co-culture, membraneless organelles, and artificial cell environments. Understanding their behavior necessitates the ability to create, capture, and observe ATPS droplets in a controlled manner, varying conditions over time. Traditional microfluidics methods, however, present significant challenges due to the extremely low interfacial tension between ATPS droplets and the continuous phase, leading to poor size control, wide size distribution, and poor reproducibility.

This research presents a novel microfluidics-based approach, designed to robustly and precisely create and capture ATPS droplets. Our technique employs individual fluidic chambers for each droplet's formation and containment, arranged in dead-end side channels of a primary fluidic channel and connected via a thin connecting channel. This layout offers superior control over traditional ATPS droplet creation methods, enabling concentration manipulation in each trap by adjusting diffusion, exposure time to different fluids in the main channel, and the geometry of each connecting channel.

We validate our system using the established dextran/PEG ATPS system, demonstrating a phase diagram congruent with previous findings. Our methodology facilitates the creation of diverse conditions within a single experiment, significantly enhancing ATPS studies' efficiency and versatility. Our tool can be applied to a wide range of systems. For example, we have used it to study associative liquid-liquid phase separation and the formation of coacervates. We have even applied it to a non-aqueous system in forming liquid crystal droplets. We have also extended the applicability of the approach by fabricating devices that incorporate pneumatically activated valves between different fluidic traps. This further broadens the scope of our technique, allowing for the examination of communication between varied environments.