Quantitative evaluation of methods to analyze motion changes in single-particle experiments.

The analysis of live-cell single-molecule imaging experiments can reveal valuable information about the heterogeneity of transport processes and interactions between cell components. These characteristics are seen as motion changes in the particle trajectories. Despite the existence of multiple approaches to carry out this type of analysis, no objective assessment of these methods has been performed so far.

Roadmap for animate matter.

Humanity has long sought inspiration from nature to innovate materials and devices. As science advances, nature-inspired materials are becoming part of our lives. Animate materials, characterized by their activity, adaptability, and autonomy, emulate properties of living systems.

Three-dimensional model for surface accumulation of chiral and nonchiral microswimmers.

Persistent motion of microswimmers near boundaries is known to result in surface accumulation. A way to control surface accumulation is by reducing the contact surface area between swimmers and surface by modifying its topography, typically through the application of microscale structures. In this work, we introduce a three-dimensional (3D) phenomenological model of a microswimmer navigating a volume bounded by a top and bottom surface.

Capillary-assisted printing of droplets at a solid-like liquid-liquid interface.

Hypothesis: Nanoparticle surfactants ('NPS') assemble at the oil-water interface to form solid-like films. Aqueous droplets placed on these solid-like oil-water interfaces are expected to be stable against coalescence with the underlying water phase. These droplets will deform the solid-like interface at which they are placed, leading to capillary forces and the assembly of large, multi-droplet structures.

Thermoplasmonic Polymersome Membranes by Synthesis.

Thermoplasmonic nanoparticles, known for releasing heat upon illumination, find diverse applications in catalysis, optics, and biomedicine. Incorporating plasmonic metals within organic vesicle membranes can lead to the formation of nanoreactors capable of regulating temperature-sensitive microscopic processes. Yet, the controlled formation of stable hybrid vesicles displaying significant thermoplasmonic properties remains challenging.

Optimal face-to-face coupling for fast self-folding kirigami.

Kirigami-inspired designs can enable self-folding three-dimensional materials from flat, two-dimensional sheets. Hierarchical designs of connected levels increase the diversity of possible target structures, yet they can lead to longer folding times in the presence of fluctuations. Here, we study the effect of rotational coupling between levels on the self-folding of two-level kirigami designs driven by thermal noise in a fluid.

Environmental memory boosts group formation of clueless individuals.

The formation of groups of interacting individuals improves performance and fitness in many decentralised systems, from micro-organisms to social insects, from robotic swarms to artificial intelligence algorithms. Often, group formation and high-level coordination in these systems emerge from individuals with limited information-processing capabilities implementing low-level rules of communication to signal to each other. Here, we show that, even in a community of clueless individuals incapable of processing information and communicating, a dynamic environment can coordinate group formation by transiently storing memory of the earlier passage of individuals.

Light, Matter, Action: Shining Light on Active Matter.

Light carries energy and momentum. It can therefore alter the motion of objects on the atomic to astronomical scales. Being widely available, readily controllable, and broadly biocompatible, light is also an ideal tool to propel microscopic particles, drive them out of thermodynamic equilibrium, and make them active.

Steering self-organisation through confinement.

Self-organisation is the spontaneous emergence of spatio-temporal structures and patterns from the interaction of smaller individual units. Examples are found across many scales in very different systems and scientific disciplines, from physics, materials science and robotics to biology, geophysics and astronomy. Recent research has highlighted how self-organisation can be both mediated and controlled by confinement.

Active matter in space.

In the last 20 years, active matter has been a highly dynamic field of research, bridging fundamental aspects of non-equilibrium thermodynamics with applications to biology, robotics, and nano-medicine. Active matter systems are composed of units that can harvest and harness energy and information from their environment to generate complex collective behaviours and forms of self-organisation. On Earth, gravity-driven phenomena (such as sedimentation and convection) often dominate or conceal the emergence of these dynamics, especially for soft active matter systems where typical interactions are of the order of the thermal energy.

The role of disorder in the motion of chiral active particles in the presence of obstacles.

The presence of obstacles is intuitively expected to hinder the diffusive transport of active particles. However, for chiral active particles, a low density of obstacles near a surface can enhance their diffusive behavior. Here, we study numerically the role that disorder plays in determining the transport dynamics of chiral active particles on surfaces with obstacles.

Objective comparison of methods to decode anomalous diffusion.

Deviations from Brownian motion leading to anomalous diffusion are found in transport dynamics from quantum physics to life sciences. The characterization of anomalous diffusion from the measurement of an individual trajectory is a challenging task, which traditionally relies on calculating the trajectory mean squared displacement. However, this approach breaks down for cases of practical interest, e.

Visualization of Directional Beaming of Weakly Localized Raman from a Random Network of Silicon Nanowires.

Disordered optical media are an emerging class of materials that can strongly scatter light. These materials are useful to investigate light transport phenomena and for applications in imaging, sensing and energy storage. While coherent light can be generated using such materials, its directional emission is typically hampered by their strong scattering nature.

Nonmonotonic contactless manipulation of binary droplets via sensing of localized vapor sources on pristine substrates.

Droplet motion on surfaces influences phenomena as diverse as microfluidic liquid handling, printing technology, and energy harvesting. Typically, droplets are set in motion by inducing energy gradients on a substrate or flow on their free surface. Current configurations for controllable droplet manipulation have limited applicability as they rely on carefully tailored wettability gradients and/or bespoke substrates.

Microscale Marangoni Surfers.

We apply laser light to induce the asymmetric heating of Janus colloids adsorbed at water-oil interfaces and realize active micrometric "Marangoni surfers." The coupling of temperature and surfactant concentration gradients generates Marangoni stresses leading to self-propulsion. Particle velocities span 4 orders of magnitude, from microns/s to cm/s, depending on laser power and surfactant concentration.

Advances towards programmable droplet transport on solid surfaces and its applications.

Droplets moving on solid surfaces are at the heart of many phenomena of fundamental and applied interest in chemistry, physics and materials science. On the fundamental side, as they are often subject to evaporation, these droplets are a beautiful and complex example of non-equilibrium physical chemistry, whose explanation and understanding still capture the imagination of multiple researchers around the world. In technology, droplets on solid surfaces are of widespread use for handling small amounts of matter, for harvesting energy, for manufacturing materials and for sensing chemical and biological analytes.

Ordering of binary colloidal crystals by random potentials.

Structural defects are ubiquitous in condensed matter, and not always a nuisance. For example, they underlie phenomena such as Anderson localization and hyperuniformity, and they are now being exploited to engineer novel materials. Here, we show experimentally that the density of structural defects in a 2D binary colloidal crystal can be engineered with a random potential.

Far-Field Wavefront Control of Nonlinear Luminescence in Disordered Gold Metasurfaces.

We demonstrate the local optimization of nonlinear luminescence from disordered gold metasurfaces by shaping the phase of femtosecond excitation. This process is enabled by the far-field wavefront control of plasmonic modes delocalized over the sample surface, leading to a coherent enhancement of subwavelength electric fields. In practice, the increase in nonlinear luminescence is strongly sensitive to both the nanometer-scale morphology and the level of structural complexity of the gold metasurface.

Enhanced propagation of motile bacteria on surfaces due to forward scattering.

How motile bacteria move near a surface is a problem of fundamental biophysical interest and is key to the emergence of several phenomena of biological, ecological and medical relevance, including biofilm formation. Solid boundaries can strongly influence a cell's propulsion mechanism, thus leading many flagellated bacteria to describe long circular trajectories stably entrapped by the surface. Experimental studies on near-surface bacterial motility have, however, neglected the fact that real environments have typical microstructures varying on the scale of the cells' motion.

Active matter alters the growth dynamics of coffee rings.

How particles are deposited at the edge of evaporating droplets, i.e. the coffee ring effect, plays a crucial role in phenomena as diverse as thin-film deposition, self-assembly, and biofilm formation.

High-performance reconstruction of microscopic force fields from Brownian trajectories.

The accurate measurement of microscopic force fields is crucial in many branches of science and technology, from biophotonics and mechanobiology to microscopy and optomechanics. These forces are often probed by analysing their influence on the motion of Brownian particles. Here we introduce a powerful algorithm for microscopic force reconstruction via maximum-likelihood-estimator analysis (FORMA) to retrieve the force field acting on a Brownian particle from the analysis of its displacements.

Dynamic Control of Particle Deposition in Evaporating Droplets by an External Point Source of Vapor.

The deposition of particles on a surface by an evaporating sessile droplet is important for phenomena as diverse as printing, thin-film deposition, and self-assembly. The shape of the final deposit depends on the flows within the droplet during evaporation. These flows are typically determined at the onset of the process by the intrinsic physical, chemical, and geometrical properties of the droplet and its environment.

The topography of the environment alters the optimal search strategy for active particles.

In environments with scarce resources, adopting the right search strategy can make the difference between succeeding and failing, even between life and death. At different scales, this applies to molecular encounters in the cell cytoplasm, to animals looking for food or mates in natural landscapes, to rescuers during search and rescue operations in disaster zones, and to genetic computer algorithms exploring parameter spaces. When looking for sparse targets in a homogeneous environment, a combination of ballistic and diffusive steps is considered optimal; in particular, more ballistic Lévy flights with exponent [Formula: see text] are generally believed to optimize the search process.

Chemotactic synthetic vesicles: Design and applications in blood-brain barrier crossing.

In recent years, scientists have created artificial microscopic and nanoscopic self-propelling particles, often referred to as nano- or microswimmers, capable of mimicking biological locomotion and taxis. This active diffusion enables the engineering of complex operations that so far have not been possible at the micro- and nanoscale. One of the most promising tasks is the ability to engineer nanocarriers that can autonomously navigate within tissues and organs, accessing nearly every site of the human body guided by endogenous chemical gradients.