Microswimmers – From Single Particle Motion to Collective Behavior

Abstract

Abstract. Locomotion of autonomous microswimmers is a fascinating field at the cutting edge of science. It combines the biophysics of selfpropulsion via motor proteins, artificial propulsion mechanisms, swimming strategies at low Reynolds numbers, the hydrodynamic interaction of swimmers, and the collective motion and synchronisation of large numbers of agents. The articles of this Special Issue are based on the lecture notes of an international summer school, which was organized by the DFG Priority Programme 1726 "Microswimmers -From Single Particle Motion to Collective Behaviour" in the fall of 2015. The minireviews provide a broad overview of the field, covering both elementary and advanced material, as well as selected areas from current research.

Large scale micro-photometry for high resolution pH-characterization during electro-osmotic pumping and modular micro-swimming

“…These are nearly always very complex due to the interplay between gradients from individual particles and the perturbation from neighboring particles [4,5]. Different approaches of nonequilibrium statistical physics have been applied in studies on the self-assembly of active particles [3,66,67], however, only a few theories have explicitly taken the details of interactions into account [48,68]. We anticipate that mapping out the involved local gradients, their evolutions and fluctuations in sufficient detail will yield valuable complementary information to standard particle tracking approaches.…”

Modeling Chemotaxis of Microswimmers: From Individual to Collective Behavior

“…A more complicated coupling involves a concentration dependent prefactor α as proposed in Ref. 14 We will basically use and discuss formula (18) in the sequel. The effective chemotactic force typically acts on a completely overdamped particle with position r p (t), leading to the following equation of motion:…”

Brownian Thermometry Beyond Equilibrium

“…They are still a very active field of research, posing a wide variety of problems. Interesting topics of recent research are systems with slow relaxation (e. g. aging in molecular glasses), strongly driven systems (e. g. granular matter or strongly perturbed colloidal systems), and active matter (comprising, e. g., living organisms and artificial microswimmers) …”

“…Interesting topics of recent research are systems with slow relaxation (e. g. aging in molecular glasses), strongly driven systems (e. g. granular matter or strongly perturbed colloidal systems), and active matter (comprising, e. g., living organisms and artificial microswimmers). [7,43,9,59] A key feature of equilibrium statistical mechanics is that it provides a means to accurately describe macroscopic systems in terms of a small number of thermodynamic variables (e. g. temperature, pressure). Far from equilibrium an analogous general framework is not available, and the very existence of key concepts of thermodynamics such as pressure or temperature is a priori questionable.…”

“…A recent collection of minireviews on the topics of biological and artificial swimmers as well as collective motion can be found in. [43] To refer to the common traits of such living and biomimetic systems, the notion of "active matter" has been coined for this important class of non-equilibrium many-body systems that are not driven by some external forces but by "intrinsic" energyconsuming mechanisms. The active mechanisms break detailed balance on a microsopic or mesoscopic scale.…”