Dynamics of droplet formation at T-shaped nozzles with elastic feed lines

Title

Author

Malsch, D.
Gleichmann, N.
Kielpinski, M.
Mayer, G.
Henkel, T.
Mueller, D.
Van Steijn, V.
Kleijn, C.
Kreutzer, M.T.

Faculty

Applied Sciences

Department

Chemical Engineering

Abstract

We describe the formation of water in oil droplets, which are commonly used in lab-on-a-chip systems for sample generation and dosing, at microfluidic Tshaped nozzles from elastic feed lines. A narrow nozzle forms a barrier for a liquid–liquid interface, such that pressure can build up behind the nozzle up to a critical pressure. Above this critical pressure, the liquid bursts into the main channel. Build-up of pressure is possible when the fluid before the nozzle is compressible or when the channel that leads to the nozzle is elastic. We explore the value of the critical pressure and the time required to achieve it. We describe the fluid flow of the sudden burst, globally in terms of flow rate into the channel and spatially resolved in terms of flow fields measured using micro-PIV. A total of three different stages—the lag phase, a spill out phase, and a linear growth phase—can be clearly discriminated during droplet formation. The lag time linearly scales with the curvature of the interface inside the nozzle and is inversly proportional to the flow rate of the dispersed phase. A complete overview of the evolution of the growth of droplets and the internal flow structure is provided in the digital supplement

Subject

segmented flow
droplet formation
micro particle image velocimetry (lPIV)
micro channel
oil/water two phase flow
digital reaction technology
droplet-based microfluidics platform

To reference this document use:

http://resolver.tudelft.nl/uuid:cd5bfe29-81ba-4ce1-aad8-6854dd2164b3

DOI

https://doi.org/10.1007/s10404-009-0479-5

Publisher

Springer

ISSN

1613-4982

Source

Microfluidics and Nanofluidics, 8 (4), 2010