Microfluidics & Emulsions

The use of microfluidic modules enables the production and control of calibrated droplets. This accurate control on droplet shapes and interfaces provides means to extract quantitative informations on interfaces, in statics and dynamics. We are for example interested in transient states in emulsion stabilisation by surfactants and their link to dynamic surface tensions.


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.

Permeation processes in emulsions: A microfluidic study

The transport of chemicals between droplets in an emulsion is a problem of both fundamental interest to understand ageing of emulsion and of practical relevance for the storage of chemical compounds as library in droplets. Over the past years, several applications have been hindered by the uncontrolled exchange process and the lack of understanding of the underlying phenomena.

Here we used a microfluidic system to systematically study the exchange process in fluorinated emulsions and we established quantitatively the crucial role of surfactant. We also clarified the role of additives such as proteins which are known to slow down the exchange kinetics.

Our approach leads to a better understanding of molecular transport which will be valuable for the control of experimental conditions for droplet-based microfluidic applications.

More informations: http://pubs.rsc.org/en/content/articlelanding/2012/sm/c2sm25934f

Imaging of surfactant stabilized nanostructures using microfluidics
Project B12 within the SFB 755 - Nanoscale Photonic Imaging

Our aim is to study how the microscopic and nanoscopic details of interfaces drive the macroscopic behavior of two-phase fluids. Using x-ray imaging techniques and fluorescence microscopy we want to resolve the dynamics of transient mechanisms such as bilayer formation and rupture, network formation of bilayers, and micellar or surfactant transport. We will use microfluidic systems to control these structures to provide new quantitative insights in the understanding of dynamical processes in multiphase fluids.

Other collaborations

Prof. Andrew Griffiths, ISIS, University of Strasbourg / CNRS (France)
Dr. Estelle Mayot, ISIS, University of Strasbourg / CNRS (France)
Prof. Stephan Herminghaus, MPI for Dynamics and Self-organisation, Goettingen (Germany)

Related PhD Thesis in the Group

Related Publications

A new-to-nature carboxylation module to improve natural and synthetic CO2 fixation
M. Scheffen, D.G. Marchal, T. Beneyton, S. K. Schuller, M. Klose, C. Diehl, J. Lehmann, P. Pfister, M. Carrillo, H. He, S. Aslan, N. S. Cortina, P. Claus, D. Bollschweiler, J.-C. Baret, J. M. Schuller, J. Zarzycki, A. Bar-Even and T. J. Erb
Nature Catalysis (2021)
pdfOpen Access
Out-of-equilibrium microcompartments for the bottom-up integration of metabolic functions
T. Beneyton, D. Krafft, C. Bednarz, C. Kleineberg, C. Woelfer, I. Ivanov, T. Vidakovic-Koch, K. Sundmacher and J.-C. Baret
Nature Communications, 9:2391 (2018)
pdfOpen Access
Dynamics of molecular transport by surfactants in emulsions
Y. Skhiri,
P. Gruner, B. Semin, Q. Brosseau, D. Pekin, L. Mazutis, V. Goust, F. Kleinschmidt, A. El Harrak, J.B. Hutchison, E. Mayot, J.-F. Bartolo, A.D. Griffiths, V. Taly, J.-C. Baret
Soft Matter 8, 10618-10627 (2012)
Kinetic aspects of emulsion stabilization by surfactants: a microfluidic analysis
J.-C. Baret, F. Kleinschmidt, A. El Harrak, and A. D. Griffiths
Langmuir 25, 6088 (2009)

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