Bäumchen group

Research

Our experimental expertise include atomic force microscopy, ellipsometry, microfluidics & lab-on-a-chip technologies, cell cultivation, microfabrication, digital image processing & analysis and state-of-the-art optical microscopy involving high-speed, fluorescence & contrast-enhancing imaging modes. In addition, we successfully developed a unique in vivo micropipette force spectroscopy technique that allows for measuring forces down to the piconewton level in living cells, multicellular systems, microorganisms and biological tissue.

The research group has established fruitful collaborations and active exchanges with experimental and theory groups within the MPI-DS as well as outside the institute, e.g. at McMaster University (Hamilton, Canada), ESPCI - Paris Tech (Paris, France), ENS (Paris, France), University of Bordeaux (Bordeaux, France), Cornell University (Ithaca, USA), Oxford University (Oxford, UK), HU and TU Berlin (Berlin, Germany), Georg-August University of Göttingen (Göttingen, Germany), Saarland University (Saarbrücken, Germany) and others.

1.  Living Matter in Confinement: The Physics of Life in Complex Geometries

The natural habitats of many living microorganisms are complex geometric environments. For motile organisms like bacteria and microalgae that propel themselves through a liquid medium within their microhabitat, the prevailing picture is that the precise nature of contact and hydrodynamic forces governs their interactions with interfaces. The way these flagellated cells explore the domain boundaries in confinement entails important implications for the colonization of porous media and the formation of biofilms in applications such as water filtration, bioremediation, biofuel production and targeted cargo delivery. 

2. Living Matter at Interfaces: Cell Adhesion and Cell Motility

Interfacial forces play a crucial role in cell adhesion and cell motility, as well as the transition between the planktonic and the surface-associated state. We have successfully designed a novel micropipette force spectroscopy technique for time-resolved  in-vivo force measurements in biological systems. While quantifying forces in living systems down to the piconewton level, the technique allows for simultaneously correlating these forces to the shape of the object and its contact area with an interface. In combination with state-of-the-art microscopy and high-speed as well as fluorescence imaging, the technique provides access to forces in a wide range of living systems, including single cells, multicellular aggregates, and microorganisms. These insights are highly relevant for understanding the emergence of biofilms and have a broad spectrum of applications with regard to renewable energy and the development of pharmaceuticals.

3. Micro- and Nanofluidics - Wetting, Contact Line Physics and Elasto-Capillarity

Thin liquid films are ubiquitous in every-day life and technology. The understanding of whether or not a thin liquid film, such as a coating or a lubricant, wets a surface is of great importance in microchip fabrication technologies and manufacturing processes. If the film is unstable, different rupture mechanisms create characteristic liquid morphologies and the emerging patterns reveal the intermolecular forces at play. The dynamics of complex liquids at interfaces is not only affected by intermolecular interactions and friction between the liquid and the substrate, but also by the ability of a soft substrate to be deformed. We study the complex interplay between the capillarity of a liquid and the elasticity of soft materials and compare our experimental results to numerical simulations and analytical models.

4. Micro- and Nanofluidics – The Hydrodynamic Boundary Condition Revisited

The flow of complex liquids on small length scales is often purely driven by capillary forces. Starting from any non-flat surface geometry, a thin liquid film approaches its equilibrium state by reducing its surface area. Such liquid instabilities create unique micro- and nanofluidic features that can be captured by analytical models and numerical calculations. The full description of the dynamics, scalings and self-similarities are powerful tools to address key challenges in light of the precise control of minute amounts of liquids: Can liquids slide? What are the parameters that govern the hydrodynamic boundary condition? Does confinement alter the mobility of liquids? The no-slip boundary condition typically holds for macroscopic flows. However, on very small scales such as thin liquid films and microdroplets, hydrodynamic slip may strongly affect liquid transport.

5. Lab-on-a-Chip Technologies: Fabrication and Control of Functionalized Vesicles

Synthetic biology appears as an emerging field of research for mimicking natural systems, taking a bottom-up approach for the design of functional biological units. A key challenge in this field is the fabrication of microcompartments exhibiting tailored physical properties and biological functionalities. Within the MaxSynBio initiative of the Federal Ministry of Science and Education (BMBF) and the Max Planck Society, we develop microfluidic technologies for the high-throughput production of functionalized compartments that exhibit tailored properties, based on the self-assembly of phospholipids and block-copolymers in a vesicle membrane.
 
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