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Swarmalators offer a framework to study how spatial organization and internal dynamics co-evolve in natural and engineered collectives. Here, the authors present an experimental colloidal swarmalator system with tunable synchronization-motion coupling, revealing emergent collective states and a novel synchronization-dependent interaction mechanism.

Classical fluids dissipate energy irreversibly as heat. Here, the authors experimentally show that in complex fluids with memory, energy can be recuperated, lowering effective friction and revealing how microscopic systems can transiently store and later return energy to perform useful work.

The melting process in glasses is not fully understood. Experiments with colloidal glasses now show that during melting, a liquid film develops at the surface, below which a region forms with highly mobile particles. This surface glassy layer reflects the properties of the surface and the underlying bulk material.

The Magnus effect refers to rotating objects developing a lift force when travelling through a fluid. It normally vanishes at microscopic length scales but now a very large Magnus effect is demonstrated for spinning colloids in viscoelastic fluids.

The plastic flow of crystals takes place via the elementary flow of topological defects and is strongly influenced by the presence of grain boundaries. Here, the authors show how the atomic structure of grain boundaries affects the dynamics of interstitial defects driven across monolayer colloidal polycrystals.

Bacteria communicate and organize via quorum sensing which is determined by biochemical processes. Here the authors aim to reproduce this behaviour in a system of synthetic active particles whose motion is induced by an external beam which is in turn controlled by a feedback-loop which mimics quorum sensing.

The amoebae Dictyostelium have previously been observed to migrate counter to the direction of a traveling chemical wave. Here the authors demonstrate that light-activated phototactic synthetic particles move counter to the pulse direction in a way which is reminiscent of the amoebae’s behavior.

Living organisms, like fish and bacteria, frequently change their pattern as a group to cope with environment. Here, Bäuerle et al. reproduce this phenomenon using a synthetic system of controllably interactive colloids to show their collective motions that indicates being close to a critical point.

The motion of microparticles suspended in liquids is assumed to be dominated by viscous forces. Here, Berner et al. challenge this consensus by observing underdamped particle oscillations in a viscoelastic fluid and attributing it to the non-equilibrium fluctuations of liquid excited by particles.

Gravitaxis describes the ability of microorganisms to adjust their swimming motion on the gravitational field, yet its mechanism remains unclear. Here, the authors show that an asymmetric shape of colloidal particles is alone sufficient to induce gravitactic motion in the absence of density inhomogeneity.

The capability to move towards or away from light sources, namely phototaxis, is an essential feature of many microorganisms like bacteria or motile cells. Lozano et al. show an artificial phototaxis system that enables autonomous navigation of colloidal Janus spheres in a laser-generated light landscape.

The rotational dynamics of self-propelled microparticles suspended in a colloidal glass is sharply increased at the glass transition of the system while their translation diffusion is strongly hindered.

The frictional properties of a two-dimensional colloidal crystal reveal that excitations known as kinks and antikinks form when the crystal is dragged along a solid surface. This phenomenon, which was predicted previously but never observed, demonstrates the potential of using colloidal crystals to study frictional properties that are otherwise difficult to characterize.

An optically trapped colloidal particle serves as the first realization of a stochastic thermal engine, extending our understanding of the thermodynamics behind the Carnot cycle to microscopic scales where fluctuations dominate.

Minimally invasive surgeries call for surgical tools that can work at the mesoscale. Here, Gu et al. present a class of magnetic soft robotic chains that can self fold into large assemblies with stable configurations using a combination of elastic and magnetic energies stored in printed chain material.

Colloidal clusters are shown to undergo directional locking when driven across a patterned surface. The role of the Fourier components of the particle–surface interaction suggests a means of leveraging this behaviour for nanoscale manipulation.

Structural lubricity is one of the most interesting concepts in modern tribology, which promises to achieve ultra-low friction over a wide range of length-scales. Here the authors highlight novel research lines in this area achievable by combining theoretical and experimental efforts on hard two-dimensional materials and soft colloidal and cold ion systems.

An outstanding challenge in active matter physics is to control the motion of active particles. Here, the authors present a motility trap that can be applied to any self-propulsion scheme, and combine experiments, theory, and simulations to demonstrate robust spatio-temporal control of active particles.