In this Letter, we explore experimentally the phase behavior of a dense active suspension self-propelled colloids. addition to solidlike and gaslike observed for high low densities, novel cluster is reported at intermediate densities. This takes form stationary assembly aggregates-resulting from permanent dynamical merging separation colloids-whose average size grows with activity as linear function self-propelling velocity. While different possible scenarios can be considered account these...

In this Letter, we investigate experimentally the nonequilibrium steady state of an active colloidal suspension under gravity field. The particles are made chemically powered colloids, showing self propulsion in presence added fuel, here hydrogen peroxide. is studied a dedicated microfluidic device, permeable gel microstructures. Both microdynamics individual colloids and global stationary measured with optical microscopy. This yields direct measurement effective temperature system as...

We present in this Letter an experimental characterization of liquid flow slippage over superhydrophobic surfaces made carbon nanotube forests, incorporated microchannels. make use a particle image velocimetry technique to achieve the submicrometric resolution on profile necessary for accurate measurement surface hydrodynamic properties. demonstrate boundary Cassie state, associated with slip lengths few microns, while vanishing length is found Wenzel state when impregnates surface. Varying...

We report an accurate determination of the hydrodynamic boundary condition simple liquids flowing on smooth hydrophobic surfaces using a dynamic surface force apparatus equipped with two independent subnanometer resolution sensors. The slip observed is well defined and does not depend scale investigation from one to several hundreds nanometers, nor shear rate up 5 x 10(3)s(-1). length 20 nm in good agreement theory numerical simulations concerning nonwetting surfaces. These results disagree...

We investigate the hydrodynamic friction properties of superhydrophobic surfaces and quantify their superlubricating potential. On such surfaces, contact liquid with solid roughness is minimal, while most interface a liquid-gas one, resulting in strongly reduced friction. obtain scaling laws for effective slip length at surface terms generic characteristics (roughness scale, depth, fraction interface, etc.). These predictions are successfully compared to numerical results various geometries...

The ubiquitous aquaporin channels are able to conduct water across cell membranes, combining the seemingly antagonist functions of a very high selectivity with remarkable permeability. Whereas molecular details obvious keys perform these tasks, overall efficiency transport in such nanopores is also strongly limited by viscous dissipation arising at connection between nanoconstriction and nearby bulk reservoirs. In this contribution, we focus on so-called entrance effects specifically examine...

A remarkable feature of active matter is the propensity to self-organize. One striking instance this ability generate spatial structures cluster phase, where clusters broadly distributed in size constantly move and evolve through particle exchange, breaking or merging. Here we propose an exhaustive description dynamics apolar matter. Exploiting large statistics gathered on thousands Janus colloids, measure aggregation fragmentation rates rationalize resulting distribution fluctuations. We...

In this Letter, we characterize experimentally the diffusiophoretic motion of colloids and lambda-DNA toward higher concentration solutes, using microfluidic technology to build spatially temporally controlled gradients. We then demonstrate that segregation spatial patterning particles can be achieved from temporal variations solute profile. This takes form a strong trapping potential, stemming an osmotically induced rectification mechanism time-dependent variations. Depending on symmetry...

Active colloids constitute a novel class of materials composed colloidal-scale particles locally converting chemical energy into motility, mimicking micro-organisms. Evolving far from equilibrium, these systems display structural organizations and dynamical properties distinct thermalized colloidal assemblies. Harvesting the potential this new requires development conceptual framework to describe intrinsically nonequilibrium systems. We use sedimentation experiments probe equation state...

Osmosis across membranes is intrinsically associated with the concept of semipermeability. Here, however, we demonstrate that osmotic flow can be generated by solute gradients nonselective, fully permeable nanochannels. Using a fluorescence imaging technique, are able to measure water rate inside single nanochannels an unprecedented sensitivity femtoliters per minute rates. Our results indicate onset convective liquid motion under salinity gradients, from higher lower electrolyte...

We demonstrate, using molecular-dynamics computer simulations, the strong influence of surface wettability on equilibrium structure electrical double layer at solid interfaces and electrokinetic transport in aqueous electrolytes due to effects interfacial ion specificity hydrodynamic slip. In particular, we show that anomalous such as nonzero zeta potentials for uncharged surfaces are general features electro-osmotic flow hydrophobic channels with substantial cation/anion size asymmetry, a...

We present a photolithographic route to form colloidal particles of uniform size and nonspherical shape. demonstrate the induction tunable, shape-selective interactions among these based on depletion, van der Waals, electrostatic forces in aqueous dispersions. Under appropriate conditions, self-assemble into ordered, highly anisotropic structures.

A dynamic surface force apparatus is used to determine the intrinsic flow boundary condition of two simple liquids, water and dodecane, on various smooth surfaces. We demonstrate impact experimental errors data analysis accuracy slip length determination. In all systems investigated, dissipation described by a well-defined accounting for whole range separation, film thickness, shear rate. no-slip found in wetting situations. On strongly hydrophobic surfaces, undergoes finite slippage that...

Diffusiophoretic motion of colloids and macromolecules under salt gradients exhibits a logarithmic-sensing, i.e. the particle velocity is proportional to spatial gradient logarithm concentration, as VDP = DDP∇logc. Here we explore experimentally implications this log-sensing behavior, on basis hydrogel microfluidic device allowing build spatially temporally controlled gradients. We first demonstrate that non-linearity salt-taxis leads trapping particles concentration oscillations via...

We study the hydrodynamic interaction between a sphere and an elastic surface at nanoscale with dynamic force apparatus. show that interplay viscous forces deformations leads to very rich scaling properties of response, providing unique signature behavior. These are illustrated on three different examples: thick elastomer, thin elastomer film, layer micrometric bubbles. this fluid probing allows one measure Young's modulus surfaces soft layers distance, without any direct solid-solid contact.

We study experimentally the response of a dense sediment Brownian particles to self-propulsion. observe that ergodic supercooled liquid relaxation is monotonically enhanced by activity. By contrast nonergodic glass shows an order magnitude slowdown at low activities with respect passive case, followed fluidization higher activities. Our results theoretical predictions approach transition, summing up shift line. propose nonmonotonicity due competing effects activity: (i) extra energy helps...

Diffusiophoresis, i.e. the movement of macromolecules along a molecular gradient, is shown to be an efficient means drive particles in microchannels. By using generic microfluidic setup, we assess displacement silica under controlled salt gradient and provide experimental evidence for strongly enhanced migration process, amplitude which depends on nature salt. A theoretical description shows quantitative agreement with observed features. Furthermore, describe set operations such as...

We show with computer simulations that anomalous electrokinetic effects, such as ion specificity and nonzero zeta potentials for uncharged surfaces, are generic features of electro-osmotic flow in hydrophobic channels. This behavior is due to the stronger attraction larger ions ``vapor-liquidlike'' interface induced by a surface. propose an analytical model involving modified Poisson-Boltzmann description density distributions quantitatively predicts profiles. includes crucial component...

We study electro- and diffusio-osmosis of aqueous electrolytes at superhydrophobic surfaces by means computer simulation hydrodynamic theory. demonstrate that the diffusio-osmotic flow can be amplified more than 3 orders magnitude relative to in channels with a zero interfacial slip. By contrast, little enhancement is observed these for electro-osmotic flow. This amplification due combined effects enhanced slip ion surface depletion or excess air-water interfaces on surfaces. effect...