The distribution of ions and charge at solid-water interfaces plays an essential role in a wide range processes biology, geology technology. While theoretical models the solid-electrolyte interface date back to early 20th century, detailed picture structure electric double layer has remained elusive, largely because experimental techniques have not allowed direct observation behaviour ions, i.e. with subnanometer resolution. We made use recent advances high-resolution Atomic Force Microscopy...

We use a combination of high-speed video imaging and electrical measurements to study the direct conversion impact energy water drops falling onto an electrically precharged solid surface into energy. Systematic experiments at variable conditions (initial height; location relative electrodes) parameters (surface charge density; external circuit resistance; fluid conductivity) allow us describe response quantitatively without any fit based on evolution drop-substrate interfacial area. derive...

Photo(electro)catalysis with semiconducting nanoparticles (NPs) is an attractive approach to convert abundant but intermittent renewable electricity into stable chemical fuels. However, our understanding of the microscopic processes governing performance materials has been hampered by lack operando characterization techniques sufficient lateral resolution. Here, we demonstrate that local surface potentials NPs bismuth vanadate (BiVO4) and their response illumination differ between adjacent...

A microrheological model of aggregating dispersions is proposed in which the shear stress estimated as sum hydrodynamic and structural parts. The former attributed to cores fractal aggregates, behave a suspension impermeable spheres. latter accounts for forces transmitted by chains particles linking neighboring aggregates into transient network. To calculate part concept aggregation incorporated network theory, account creation breakup colloidal connecting aggregates. Rigid soft are...

We demonstrate that the equilibrium shape of composite interface between superhydrophobic surfaces and drops in Cassie state under electrowetting is determined by balance Maxwell stress Laplace pressure. Energy barriers due to pinning contact lines at edges hydrophobic pillars control transition from Wenzel state. Barriers narrow gap adjacent lateral propagation how reversible switching two wetting states can be achieved locally using suitable surface electrode geometries.

Abstract The relative wettability of oil and water on solid surfaces is generally governed by a complex competition molecular interaction forces acting in such three-phase systems. Herein, we experimentally demonstrate how the adsorption nature abundant divalent Ca 2+ cations to solid-liquid interfaces induces macroscopic wetting transition from finite contact angles (≈10°) with near-zero without cations. We developed quantitative model based DLVO theory that this transition, which observed...

Liquid drops hitting solid surfaces deform substantially under the influence of ambient air that needs to be squeezed out before liquid actually touches solid. Nanometer- and microsecond-resolved dual wavelength interferometry reveals a complex evolution interface between drop gas layer underneath. For intermediate impact speeds (We∼1…10) thickness can develop one or two local minima-reproduced in numerical calculations-that eventually lead nucleation solid-liquid contact at We-dependent...

We demonstrate an electrowetting based optical switch with tunable aperture. Under the influence of electric field a non-transparent oil film can be replaced locally by transparent water drop creating aperture through which light pass. Its diameter tuned between 0.2 and 1.2 mm varying driving voltage or frequency. The on off response time is in order 2 120 ms respectively. Finally we array switchable apertures that independently simultaneously.

Abstract Controlling the motion of drops on solid surfaces is crucial in many natural phenomena and technological processes including collection removal rain drops, cleaning technology heat exchangers. Topographic chemical heterogeneities give rise to pinning forces that can capture steer desired directions. Here we determine general physical conditions required for capturing sliding an inclined plane equipped with electrically tunable wetting defects. By mapping drop dynamics...

Adaptive micro-lenses enable the design of very compact optical systems with tunable imaging properties. Conventional adaptive suffer from substantial spherical aberration that compromises performance system. Here, we introduce a novel concept liquid superior allows for simultaneous and independent tuning both focal length asphericity. This is achieved by varying hydrostatic pressures electric fields to control shape refracting interface between an electrically conductive lens fluid...

Understanding structure and function of solid-liquid interfaces is essential for the development nanomaterials various applications including heterogeneous catalysis in liquid phase processes water splitting storage renewable electricity. The characteristic anisotropy crystalline nanoparticles believed to be their performance but remains poorly understood difficult characterize. Dual scale atomic force microscopy used measure electrostatic hydration forces faceted semiconducting SrTiO

We describe experimental studies of the deformation giant lipid bilayer vesicles in shear flow. The experiments are carried out with a counterrotating Couette apparatus. depends on mechanical properties bilayer, vesicle radius, and viscosity surrounding Newtonian liquid. show that relevant parameter is bending rigidity. A simple model has been developed describes vesicle. This takes thermal undulations into account. have obtained value for rigidity dimyristoyl-phosphatidylcholine bilayers...

We integrate a sensitive microfluidic comparator into T-junction device and report measurements of the excess pressure drop due to single moving droplet confined in rectangular microchannel. specifically focus on drops that are not coated with surfactants study effects size, viscosity capillary number their hydrodynamic resistance. In range approximately 10(-3)-10(-2), we find two distinct regimes for resistance behavior based size. regime I associated small (drop length/channel width <4),...

High-resolution atomic force microscopy is used to map the surface charge on basal planes of kaolinite nanoparticles in an ambient solution variable pH and NaCl or CaCl2 concentration. Using DLVO theory with regulation, we determine from measured force–distance curves distribution both silica-like gibbsite-like plane particles. We observe that do carry varies salt The silica facet was found be negatively charged at 4 above, whereas gibbsite positively below 7 above 7. Investigations 6 show...

We present a method to determine the local surface charge of solid–liquid interfaces from Atomic Force Microscopy (AFM) measurements that takes into account shifts adsorption/desorption equilibria protons and ions as cantilever tip approaches sample. recorded AFM force distance curves in dynamic mode with sharp tips on heterogeneous silica surfaces partially covered by gibbsite nano-particles immersed an aqueous electrolyte variable concentrations dissolved NaCl KCl at pH 5.8. Forces are...

PNIPAM microgel particles deform substantially upon adsorbing onto an air–water interface. The adsorption is initially controlled by the diffusion of to interface followed a slow exponential relaxation at long times.

A liquid drop approaching a solid surface deforms substantially under the influence of ambient air which needs to be squeezed out before can actually touch solid. We use nanometer- and microsecond-resolved dual wavelength interferometry described in Part I (also published this issue) reveal complex spatial temporal evolution layer. In low-velocity droplet impact, i.e., numbers order unity, confined layer below develops two local minima thickness. quantitatively measure bottom interface find...

Charge trapping is a long-standing problem in electrowetting on dielectric, causing reliability reduction and restricting its practical applications. Although this phenomenon investigated macroscopically, the microscopic investigations are still lacking. In work, trapped charges proven to be localized at three-phase contact line (TPCL) region by using three detecting methods-local angle measurements, (EW) probe, Kelvin probe force microscopy. Moreover, it demonstrated that EW-assisted charge...

We show that electrowetting (EW) with structured electrodes significantly modifies the distribution of drops condensing onto flat hydrophobic surfaces by aligning and enhancing coalescence. Numerical calculations demonstrate drop alignment coalescence are governed drop-size-dependent electrostatic energy landscape is imposed electrode pattern applied voltage. Such EW-controlled migration condensate alter statistical characteristics ensemble droplets. The evolution size displays self-similar...

The shear-induced particle self-diffusivity in a concentrated suspension (20%–50% solids volume fraction) of non-colloidal spheres (90 μm average diameter) was measured using new correlation technique. This method is based on the between positions tracer particles successive images and can be used to determine suspensions for different time scales. These self-diffusivities were velocity gradient vorticity directions narrow-gap Couette device values strain γΔ t ranging from 0.05 0.5, where γ...

In order to describe the steady shear behavior of weakly aggregating dispersions a microrheological model is developed. This combines concept fractal aggregation in flow with transient network modeling originally developed for polymer dynamics. The former accounts hydrodynamic stress aggregates, while latter employed calculate component arising from forces transmitted by chains particles combining neighboring aggregates into network. contribution this shown be significant at low volume...