Abstract The direct conversion of light into work allows the driving micron-sized motors in a contactless, controllable and continuous way. Light-to-work can involve either transfer optical momentum or indirect opto-thermal effects. Both strategies have been implemented using different coupling mechanisms. However, resulting efficiencies are always very low, high power densities, generally obtained by focused laser beams, required. Here we show that microfabricated gears, sitting on...

Abstract We derive the stationary probability distribution for a non-equilibrium system composed by an arbitrary number of degrees freedom that are subject to Gaussian colored noise and conservative potential. This is based on multidimensional version Unified Colored Noise Approximation. By comparing theory with numerical simulations we demonstrate theoretical density quantitatively describes accumulation active particles around repulsive obstacles. In particular, two interactions, close...

Abstract Self-propelled bacteria can be integrated into synthetic micromachines and act as biological propellers. So far, proposed designs suffer from low reproducibility, large noise levels or lack of tunability. Here we demonstrate that fast, reliable tunable bio-hybrid micromotors obtained by the self-assembly structures with genetically engineered The components consist 3D interconnected having a rotating unit capture individual an array microchambers so cells contribute maximally to...

We study experimentally and numerically the dynamics of colloidal beads confined by a harmonic potential in bath swimming E. coli bacteria. The resulting is well approximated Langevin equation for an overdamped oscillator driven combination white thermal noise exponentially correlated active noise. This scenario leads to simple generalization equipartition theorem coexistence two different effective temperatures that govern along flat curved directions landscape.

The possibility of exploiting motile microorganisms as tiny propellers represents a fascinating strategy for the transport colloidal cargoes. However, delivery on target sites usually requires external control fields to steer and trigger cargo release. need constant feedback mechanism prevents design compact devices where biopropellers could perform their tasks autonomously. Here we show that properly designed three-dimensional (3D) microstructures can define accumulation areas bacteria...

Many motile microorganisms react to environmental light cues with a variety of motility responses guiding cells towards better conditions for survival and growth. The use spatial modulators could help elucidate the mechanisms photo-movements while, at same time, providing an efficient strategy achieve temporal control cell concentration. Here we demonstrate that millions bacteria, genetically modified swim smoothly controllable speed, can be arranged into complex reconfigurable density...

The dynamics of passive colloidal tracers in a bath self-propelled particles is receiving lot attention the context nonequilibrium statistical mechanics. Here we demonstrate that active baths are also capable mediating effective interactions between suspended bodies. In particular observe swimming bacteria gives rise to short range attraction similar depletion forces equilibrium suspensions. Using numerical simulations and experiments show how features this interaction arise from combination...

Janus particles can self-assemble around microfabricated gears in reproducible configurations with a high degree of spatial and orientational order. The final configuration maximizes the torque applied on rotor leading to unidirectional steady rotating motion. interplay between geometry dynamical behavior leads self-assembly micromotors starting from randomly distributed particles. manipulation, transport, assembly microobjects is paramount importance for microengineering biological...

We present a stochastic description of model <italic>N</italic> mutually interacting active particles in the presence external fields and characterize its steady state behavior absence currents.

We investigate the transport of multiple types active colloids to target regions and find that transition rates over asymmetric energy barriers can be unbalanced by variation a local effective temperature barrier sides.

We investigate experimentally and numerically the stochastic dynamics time-dependent response of colloids subject to a small external perturbation in dense bath motile E. coli bacteria. The field is magnetic acting on superparamagnetic microbead suspended an active medium. measured linear reveals instantaneous friction kernel despite complexity bacterial bath. By comparing mean squared displacement function we detect clear violation fluctuation dissipation theorem.

The present paper studies the spontaneous velocity alignment and time-intermittency of kinetic-energy in dense phases active matter. dynamical properties are described by considering spatial correlations constructing a non-equilibrium phase diagram force density which explores homogeneous inhomogeneous

Inelastic time history analyzes (ITHA) are recognized as the most suitable tool for describing behavior of structures under seismic actions. It is clear that reliability ITHA results strongly dependent on modeling choices. One aspects still debated, in spite a large amount research, viscous damping forces. In case single degree freedom (SDOF) structure, not represented by hysteretic response commonly assumed proportional to square root system stiffness: typically research papers it declared...

Abstract We derive an analytic expression for the distribution of velocities multiple interacting active particles which we test by numerical simulations. In clear contrast with equilibrium find that are coupled to positions. Our model shows that, even two only, individual display a variance depending on interparticle separation and emergence correlations between particles. When considering systems composed many connecting overall velocity density, at mean-field level, pair function valid in...

Abstract Methods of stochastic thermodynamics and hydrodynamics are applied to a recently introduced model active particles. The consists an overdamped particle subject Gaussian coloured noise. Inspired by thermodynamics, we derive from the system’s Fokker-Planck equation average exchanges heat work with bath associated entropy production. We show that Clausius inequality holds, local (non-uniform) temperature replacing uniform usually encountered in equilibrium systems. Furthermore,...

The equations of motion active systems can be modeled in terms Ornstein-Uhlenbeck processes (OUPs) with appropriate correlators. For further theoretical studies, these should approximated to yield a Markovian picture for the dynamics and simplified steady-state condition. We perform comparative study Unified Colored Noise Approximation (UCNA) approximation scheme by Fox recently employed within this context. review approximations necessary define effective interaction potentials low-density...

Performing large-scale simulations of active particles and employing finite-size-scaling analysis, we provide exhaustive evidence that motility-induced critical point belongs to the Ising universality class.

Thermal fluctuations constantly excite all relaxation modes in an equilibrium crystal. As the temperature rises, these promote formation of defects and eventually melting. In active solids, self-propulsion "atomic" units provides additional source non-equilibrium whose effect on melting scenario is still largely unexplored. Here we show that when a colloidal crystal activated by bath swimming bacteria, solvent cooperate to define dynamic thermodynamic properties. Our system consists...

Shear-mechanical and dielectric measurements on the two monohydroxy (monoalcohol) molecular glass formers 2-ethyl-1-hexanol 2-butanol close to glass-transition temperature are presented. The shear-mechanical data obtained using piezoelectric shear-modulus gauge method covering frequencies from 1 mHz 10 kHz. relaxation spectra show processes, which follow typical scenario of a structural (alpha) an additional (Johari–Goldstein) beta relaxation. dominated by Debye-type peak with non-Debye...

We discuss different definitions of pressure for a system active spherical particles driven by non-thermal coloured noise. show that mechanical, kinetic and free-energy based approaches lead to the same result up first order in non-equilibrium expansion parameter. The prescription is on generalisation mesoscopic virial equation expresses exerted walls terms average inter-particle forces. In second approach, surface tension are identified with volume area derivatives, respectively, partition...

Abstract Active particles can self-propel by exploiting locally available energy resources. When powered light, these resources be distributed with high resolution allowing spatio-temporal modulation of motility. Here we show that the random walks light-driven bacteria are rectified when they swim in a structured light field is obtained simple geometric transformation previous system snapshot. The currents achieve an optimal value establish general theoretical arguments. This optical...

We report dynamical shear-modulus measurements for five glass-forming liquids (pentaphenyl trimethyl trisiloxane, diethyl phthalate, dibutyl 1,2-propanediol, and m-touluidine). The shear-mechanical spectra are obtained by the piezoelectric gauge (PSG) method. This technique allows one to measure shear modulus ($10^{5} -10^{10}$ Pa) of liquid within a frequency range from 1 mHz 10 kHz. analyze frequency-dependent response functions investigate whether time-temperature superposition (TTS) is...

Active particles driven by colored noise can be approximately mapped onto a system that obeys detailed balance. The effective interactions which derived for such allow to describe the structure and phase behavior of active fluid means an free energy. In this paper we explain why related thermodynamic results pressure interfacial tension do not represent one would measure mechanically. We derive dynamical density functional theory, in steady state simultaneously validates use provides access...

We numerically investigate the correlation function, response and breakdown of Fluctuation-Dissipation Theorem (FDT) in active particles close to motility-induced critical point. find a strong FDT violation short time wavelength regime, where function has larger amplitude than fluctuation spectrum. Conversely, at spatiotemporal scales, is restored slowing-down compatible with Ising universality class. Building on these results, we develop novel field-theoretical description employing...

We investigate the effect of self-propulsion on a mean-field order-disorder transition. Starting from ${\ensuremath{\varphi}}^{4}$ scalar field theory subject to an exponentially correlated noise, we exploit unified colored-noise approximation map nonequilibrium active dynamics onto effective equilibrium one. This allows us follow evolution second-order critical point as function noise parameters: correlation time $\ensuremath{\tau}$ and strength $D$. Our results suggest that universality...