Phase behavior and dynamics of active Brownian particles in an alignment field.

Self-propelled particles that are subject to noise are a well-established generic model system for active matter. A homogeneous alignment field can be used to orient the direction of the self-propulsion velocity and to model systems like phoretic Janus particles with a magnetic dipole moment or magnetotactic bacteria in an external magnetic field. Computer simulations are used to predict the phase behavior and dynamics of self-propelled Brownian particles in a homogeneous alignment field in two dimensions.

Adhesion-driven vesicle translocation through membrane-covered pores.

Translocation across barriers and through constrictions is a mechanism that is often used in vivo for transporting material between compartments. A specific example is apicomplexan parasites invading host cells through the tight junction that acts as a pore, and a similar barrier crossing is involved in drug delivery using lipid vesicles penetrating intact skin. Here, we use triangulated membranes and energy minimization to study the translocation of vesicles through pores with fixed radii.

The 2025 motile active matter roadmap.

Activity and autonomous motion are fundamental aspects of many living and engineering systems. Here, the scale of biological agents covers a wide range, from nanomotors, cytoskeleton, and cells, to insects, fish, birds, and people. Inspired by biological active systems, various types of autonomous synthetic nano- and micromachines have been designed, which provide the basis for multifunctional, highly responsive, intelligent active materials.

Capillary-driven self-assembly of soft ellipsoidal microgels at the air-water interface.

The adsorption of ellipsoidal colloidal particles on liquid interfaces induces interfacial deformation, resulting in anisotropic interface-mediated interactions and the formation of superstructures. Soft prolate-shaped microgels at the air-water interface offer an ideal model for studying spontaneous capillary-driven self-assembly due to their tunable aspect ratio, controlled functionality, and softness. These microgels consist of a polystyrene core surrounded by a cross-linked, fluorescently labeled poly([Formula: see text]-isopropylmethylacrylamide) shell.

Low efficiency of Janus microswimmers as hydrodynamic mixers.

The generation of fluid flows by autophoretic microswimmers has been proposed as a mechanism to enhance mass transport and mixing at the micro- and nanoscale. Here, we experimentally investigate the ability of model 2D active baths of photocatalytic silica-titania Janus microspheres to enhance the diffusivity of tracer particles at different microswimmer densities below the onset of collective behavior. Inspired by the similarities between our experimental findings and previous results for biological microorganisms, we then model our Janus microswimmers using a general squirmer framework, specifically treating them as neutral squirmers.