We work on a broad spectrum of projects from statistical physics of soft condensed matter and biological systems. Besides problems in thermal equilibrium, we investigate systems that are kept in nonequilibrium either by external fields or by an internal propulsion mechanism such as active Brownian particles.
The highly topical fields of microfluidics and (bio)fluid dynamics inspire us.
One current focus in our research is active motion of artificial and biological systems. We aim at understanding design principles for generating active motion, its generic properties, and the emergent collective dynamics.
Our topics are:
Soft matter: such as liquid crystals, colloidal dispersions, (bio)polymers
Structure formation of soft matter at interfaces
Soft Matter and biological systems in nonequilibrium, microfluidics
Biofluiddynamics and locomotion of microorganisms, active motion
Biomimetic materials and biomechanics
Abstract Microswimmers: From design principles to their emergent collective dynamics
Active motion of artificial and biological microswimmers is relevant in microfluidics and biological applications but also poses fundamental questions in nonequilibrium statistical physics. Mechanisms of single microswimmers either designed by nature or in the lab need to be understood and a detailed modeling of microorganisms helps to explore their complex cell design and their behavior. The emergent collective motion of microswimmers generates appealing dynamic patterns as a consequence of the non-equilibrium. In this talk I review some of our work modeling biological microswimmers such as E. coli and the African trypanosome, the causative agent of the sleeping sickness, in order to contribute to their better understanding. Using simpler model microswimmers, I will demonstrate the richness of their emerging collective behavior. Hydrodynamic simulations with multi-particle collision dynamics show motility-induced phase separation of squirmers and exponential sedimentation profiles under gravity with superimposed large-scale convection. Under strong gravity and at small densities, single layers of squirmers form hydrodynamic Wigner crystals or exhibit swarming depending on the swimmer type. Finally, self-phoretic active colloids are able to sense their environment and perform chemotactic motion mimicking bacterial systems.
Artist: Hava Friedman Logo design: Nick Kotoulas, Jennifer Tran Photography: Nick Kotoulas