Oliver Bäumchen

Dynamics of fluid and biological interfaces

oliver.baeumchen at ds.mpg.de

(+49) 551-5176-260
(+49) 551-5176-202

2.56

 

Group leader

The newly established experimental research group focuses on the physics of pattern formation in soft condensed matter systems on the micro- and nanoscale. In general, pattern formation attracts scientific interest in various disciplines: How does nature create complex morphologies out of simple building blocks on so many different time and length scales? Dew droplets on a spider’s web, ripples in sand dunes, bent shapes of rivers, cloud patterns in the sky and even the formation of galaxies are just a few familiar examples.

We are interested in structure formation on very small length scales. In particular, we study the dynamics of complex liquids and biological objects at or near interfaces. Complex liquids can be confined in various geometries such as for example thin liquid films or small droplets, supported either by flat substrates or microfibers. Our goal is also to transfer concepts from complex liquids to biological systems such as cells, lipid vesicles or even active systems such as micro-organisms. As a general approach, we are always aiming for complementing our experimental results with theoretical frameworks, based on analytical theories and/or numerical calculations.

Open positions

Currently, we are looking for new group members at all levels. Highly-motivated students or researchers that are interested in joining the group should contact me directly by email: oliver.baeumchen at ds.mpg.de. Please attach a CV and a statement of research interests to your application letter. Students that would like to learn more about the research projects in our group and want to explore the MPI research facilities and labs are, of course, also welcome to contact me. Bachelor and Master thesis projects are available any time.

Evolution of Instabilities of Liquid Surfaces

On small length scales, the flow of complex liquids is often purely driven by capillary forces. Starting from any non-flat liquid surface geometry, a thin liquid film approaches its equilibrium state by reducing its surface area: The leveling process of geometries like for example small steps, trenches or cylinders reveals unique micro- and nanofluidic features emerging from those topographic perturbations that are in excellent agreement with analytical models and numerical calculations.
The full description of the dynamics, scaling and self-similarity of such geometries is a powerful tool to address the following questions: Can liquids slide? What are the parameters that govern the sliding motion of liquids? What is the role of van-der-Waals interactions? Does confinement alter the mobility of liquids? Can we link molecular properties of the liquid to the fluid dynamics? These are key questions with regard to the precise control of minute amounts of liquids in lab-on-a-chip devices for e.g. pharmaceutical and biomedical applications.
We also take advantage of the opposite approach: Destabilizing forces, amplification of capillary waves and the minimization of the overall energy of initially unperturbed systems can lead to liquid instabilities such as the Rayleigh-Plateau instability (the decay of a liquid cylinder into droplets; also evident in the macroworld for water flowing out of a kitchen faucet). On small scales, these phenomena can be observed e.g. for dewetting liquid films and also thin liquid coatings on micro-fibers. Can we control the macroscopic pattern formation as a response to manipulating the interfacial properties?

Wetting, Adhesion & Friction of Vesicles and Cells

Established concepts such as wetting, dewetting, surface energy, viscosity and elasticity are widely applied to complex liquids like for example oil or polymeric liquids. We aim at transferring these concepts to the mechanics of biological systems. Using a novel micropipette deflection technique enables us to probe the interfacial properties of living matter like vesicles and cells. High-resolution and high-speed image capturing techniques provide a precise in-situ characterization and quantification of forces on very small scales. Gaining control on adhesion, friction and the interaction between multiple objects like vesicles or cells represents a key challenge for drug delivery and the inhibition of deceases.

Experimental techniques comprise: atomic force microscopy, optical microscopy (inverted, top-view, phase-contrast), ellipsometry and many more. A force transducer technique, based on the deflection of a micropipette in combination with state-of-the-art high-resolution cameras and image processing tools, allows for in-situ force measurements of artificial and biological objects down to pico-Newtons.

Aside from the integration and collaboration within the MPI for Dynamics and Self-Organization and, in particular, other research groups in the Department of Dynamics of Complex Fluids, we maintain very active collaborations and exchange with experimental and theory groups outside the MPI: McMaster University (Hamilton, Canada), ESPCI - Paris Tech (Paris, France), Oxford University (Oxford, UK), Technical University Berlin (Berlin, Germany), Saarland University (Saarbrücken, Germany) and many more.