Microfluidic Dynamic Interfacial Tensiometry (μDIT).
We designed, developed and characterized a microfluidic method for the measurement of surfactant adsorption kinetics via interfacial tensiometry on a microfluidic chip. The principle of the measurement is based on the deformability of droplets as a response to hydrodynamic forcing through a series of microfluidic expansions. We focus our analysis on one perfluoro surfactant molecule of practical interest for droplet-based microfluidic applications. We show that although the adsorption kinetics is much faster than the kinetics of the corresponding pendant drop experiment, our droplet-based microfluidic system has a sufficient time resolution to obtain quantitative measurement at the sub-second time-scale on nanoliter droplet volumes, leading to both a gain by a factor of ∼10 in time resolution and a downscaling of the measurement volumes by a factor of ∼1000 compared to standard techniques. Our approach provides new insight into the adsorption of surfactant molecules at liquid-liquid interfaces in a confined environment, relevant to emulsification, encapsulation and foaming, and the ability to measure adsorption and desorption rate constants.
Max-Planck Institute for Dynamics and Self-Organization (MPIDS), 37077 Göttingen, Germany. jean-christophe.baret@ds.mpg.de.
Quentin
Q
Brosseau
Jérémy
J
Vrignon
Jean-Christophe
JC
Baret
D000327:Adsorption; D000431:Ethanol / Q000737:chemistry; D004987:Ethers / Q000737:chemistry*; D017611:Fluorine Compounds / Q000737:chemistry*; D005466:Fluorocarbons / Q000737:chemistry*; D007700:Kinetics; D044085:Microfluidics; D009943:Organophosphorus Compounds / Q000737:chemistry*; D011092:Polyethylene Glycols / Q000737:chemistry*; D013501:Surface-Active Agents / Q000737:chemistry*; D014867:Water / Q000737:chemistry*
D004987:Ethers; D017611:Fluorine Compounds; D005466:Fluorocarbons; C472825:HFE-7500; D009943:Organophosphorus Compounds; D013501:Surface-Active Agents; C532209:perfluoropolyether phosphate; D014867:Water; D000431:Ethanol; D011092:Polyethylene Glycols