[en] In microfluidics flow focusing is widely used to produce water-in-oil droplets in microchannels at high frequency. Nevertheless, the scaling laws associated to droplet length, speed and frequency could not be identified yet, owing to the large number of parameters involved (incl. complex geometry).
We here present an experimental study of droplet formation in a microfluidic cross-junction with a minimum number of geometrical parameters. We mostly focus on the dripping regime.
The formation sequence is decomposed in two steps, inflation and squeezing, that vary differently according to both water and oil flow rates. These variations reveal several insights about the fluid flows in both phases. From there we infer the scaling law that relates droplet volume and frequency to the Capillary number associated to each inlet flow rate. This law involves a minimum of fitting parameters. We finally discuss the influence of inlet control (flow rate vs. pressure) and surfactants on the formation dynamics.
Research Center/Unit :
Microfluidics lab
Disciplines :
Engineering, computing & technology: Multidisciplinary, general & others
Author, co-author :
Van Loo, Stéphanie ; Université de Liège > Département d'aérospatiale et mécanique > Microfluidique
Language :
English
Title :
The mysteries of droplet birth in microfluidic cross junctions
Publication date :
June 2015
Number of pages :
A0
Event name :
Microfluidics 2015 Summer School
Event place :
Porquerolles, France
Event date :
21/06/2015 - 26/06/2015
Audience :
International
Funders :
FRIA - Fonds pour la Formation à la Recherche dans l'Industrie et dans l'Agriculture Interuniversity Attraction Poles Programme (IAP7/38 MicroMAST)