Generating aerosol droplets via the atomization of thin aqueous films with high frequency surface acoustic waves (SAWs) offers several advantages over existing nebulization methods, particularly for pulmonary drug delivery, offering droplet sizes in 1-5-μm range ideal effective therapy. Nevertheless, physics underlying SAW is not well understood, especially context liquid film formation and spreading how this affects production. Here, we demonstrate that geometry, governed primarily by...

Dynamic forces between a $50\text{ }\text{ }\ensuremath{\mu}\mathrm{m}$ radius bubble driven towards and from mica plate using an atomic force microscope in electrolyte surfactant exhibit different hydrodynamic boundary conditions at the surface. In added surfactant, are consistent with no-slip condition surfaces. With no new that accounts for transport of trace surface impurities explains variations dynamic speeds provides direct connection effects air-water interface.

A bubble attached to the end of an atomic force microscope cantilever and driven toward or away from a flat mica surface across aqueous film is used characterize dynamic that arises hydrodynamic drainage electrical double layer interactions nanometer thick intervening film. The response air/water interface can range classical fully immobile, no-slip in presence added surfactants partially mobile electrolyte solution without surfactants. model includes convection diffusion trace contaminants...

Abstract Both powerful and unstable, practical lithium metal batteries have remained a difficult challenge for over 50 years. With severe ion depletion gradients in the electrolyte during charging, they rapidly develop porosity, dendrites, dead Li that cause poor performance and, all too often, spectacular failure. Remarkably, incorporating small, 100 MHz surface acoustic wave device (SAW) solves this problem. Providing streaming flow enables dense plating avoids porosity dendrites....

We derive a generalized equation that governs the spreading of liquid films under high-frequency (MHz-order) substrate vibration in form propagating surface waves and show this single relationship is universally sufficient to collectively describe rich diverse dynamic phenomena recently observed for transport oil such excitation, particular, Rayleigh acoustic waves. In contrast low-frequency (Hz- kHz-order) vibration-induced wetting phenomena, film at high frequencies arises from convective...

Polymeric stabilizers are used in a broad range of processes and products, from pharmaceuticals engine lubricants to formulated foods shampoos. In rigid particulate systems, the stabilization mechanism is attributed repulsive force that arises compression polymer coating or "steric brush" on interacting particles. This has dictated design selection for more than thirty years. Here we show, through direct measurement interactions between immobilized drops with adsorbed polymers layers aqueous...

Arising from an interplay between capillary, acoustic and intermolecular forces, surface waves (SAWs) are observed to drive a unique curious double flow reversal in the spreading of thin films. With thickness at or less than submicrometre viscous penetration depth, film is seen advance along SAW propagation direction, self-similarly over time t 1/4 inertial limit. At intermediate thicknesses, beyond one-fourth sound wavelength λ ℓ liquid, direction reverses, propagates against propagation....

We study a fifty-year-old problem of fast acoustic streaming, that is, the generation moderate or large hydrodynamic Reynolds number ( $\textit {Re}$ ) streaming (or steady flow) by convection momentum in an wave another periodic flow), while latter is simultaneously altered former. The intrinsic disparity length and time scales makes brute-force solution full Navier–Stokes continuity equations formidable problem. Circumventing this difficulty, we split into time-averaged system for flow...

The interaction of surface acoustic waves (SAWs) with liquids enables the production aerosols adjustable droplet sizes in micrometer range expelled from a very compact source. Understanding nonlinear acousto-hydrodynamics SAWs regulated micro-scale liquid film is essential for acousto-microfluidics platforms, particularly aerosol generators. In this study, we demonstrate presence micro-cavitation MHz-frequency SAW generation platform, which touted as leap technology versatile application...

We explore the peculiar steady component of a sessile drop response to MHz order vibration, found be dependent on its initial wettability. Placed vibrating hydrophobic substrate, elongates vertically in direction incident sound wave while remaining hydrophobic. In contrast, is seen spread slightly hydrophilic substrate. elucidate this discrepancy by revealing competing effects between radiation pressure exerted at bulk air/water interface and acoustic streaming force contact line, critical...

Abstract The classical Schlichting boundary layer theory is extended to account for the excitation of generalized surface waves in frequency and velocity amplitude range commonly used microfluidic applications, including Rayleigh Sezawa Lamb, flexural surface-skimming bulk waves. These possess longitudinal transverse displacements similar magnitude along boundary, often spatiotemporally out phase, giving rise a periodic flow shown consist superposition streaming uniaxial that have no net...

We investigate the depletion contributions to self-assembly of microcolloids on solid substrates. The assembly is driven by exclusion nanoparticles and nonadsorbing polymers from zone between in liquid underlying substrate. model system consists 1 μm polystyrene particles that we deposit a flat glass slab an electrolyte solution. Using poly(acrylic acid) as depleting agents, demonstrate our experiments nanoparticle concentrations 0.5% (w/v) support well-ordered packing glass, while presence...

Oil and water phases placed on top of a solid surface respond differently to MHz-level acoustic wave (SAW) propagating in the due their different tensions corresponding capillary stresses. We observe that, under SAW excitation, oil films are extracted continuously from sessile drops silicone-oil/water/surfactant mixtures. The mechanism responsible for extraction mixtures is acoustowetting phenomenon: low tension phase leaves mixture form `fingers' that initially spread over direction...

Abstract Acoustically driven atomization from the broad perspective of materials choice, vibration mode, and fluid characteristics is considered to identify a simple method for improving both understanding phenomena overall efficiency atomization. Whether by definition “figure merit” (a function transducer quality factor electromechanical coupling coefficient), its output displacement at given input power, or flow rate during atomization, it found that combination single‐crystal 127.86°...

Poly(L-lactic acid) (PLLA) has been extensively used in tissue engineering, which its surface hydrophilicity plays an important role. In this work, efficient and green strategy developed to tailor via alkali hydrolysis. On one hand, the ester bond PLLA cleaved generates carboxyl hydroxyl groups, both of are beneficial improvement hydrophilicity. other degradation increases roughness on film surface. The resultant wettability exhibits crucial dependence crystallinity. specimen with high...

We use both theory and experiment to study the response of {\it partially wetting} films water surfactant solutions a propagating MHz vibration in solid substrate form Rayleigh surface acoustic wave (SAW). The SAW invokes drift mass liquid film, which is associated with Schlichting boundary layer flow (also known as streaming). thin that are governed by balance between capillary stress alone. demonstrate weak contributions, such for silicon oil films, support dynamic wetting lead spreading...

We evaporate aqueous suspensions in a microchamber to explore the connection between morphology of nanoparticle deposits at nanometer resolutions and micrometer hundreds micrometers resolutions. Repulsive or weakly attractive electrical double-layer van der Waals surface forces render deposition detached particles small aggregates However, strongly dense large aggregates. At greater length resolutions, deposit is further governed by evaporation-mediated transport volatile suspension. use...

Past forms of acoustic streaming, named after their progenitors Eckart (1948), Schlichting (1932), and Rayleigh (1884), serve to describe fluid particle transport phenomena from the macro micro-scale. Governed by viscosity, traditional streaming arises second-order nonlinear coupling between fluid's density velocity, with first-order wave time averaging zero. We a form acoustogeometric that has nonzero contribution. Experimentally discovered in nanochannels height commensurate viscous...

We study the deposition mechanisms of polymer from a confined meniscus volatile liquid. In particular, we investigate physical processes that are responsible for qualitative changes in pattern and underlying interplay state deposition, motion meniscus, transport within meniscus. As model system evaporate solution poly(methyl methacrylate) (PMMA) toluene. Different patterns observed when varying molecular mass, initial concentration solute, temperature; these systematically presented form...

We propose a model for the pattern deposition of solute from an evaporating drop dilute solution on horizontal substrate. In we take into account three-phase contact angle hysteresis and whenever its concentration exceeds solubility limit. The is governed by film equation. show that unless very small or rapid evaporation rate adopts quasi-steady geometry, satisfying Young-Laplace equation to leading order. profile assumed satisfy advection diffusion subject standard Fick's law diffusive...

We use both theory and experiment to study the response of thin free films a partially wetting liquid MHz vibration, propagating in solid substrate form Rayleigh surface acoustic wave (SAW). generalise previous for fully film SAW by including presence small but finite three phase contact angle between solid. The invokes convective drift mass leaks sound waves. dynamics that is too support accumulation leakage governed balance capillary stress alone. demonstrate film, supporting weak stress,...

We study the influence of a megahertz Rayleigh surface acoustic wave (SAW), propagating in solid substrate, on pattern deposition solute mass off an evaporating solution. An experimental procedure, where film solution undergoes controlled evaporation chamber, shows that SAW alters state deposition. Increasing power supports increase density deposited patterns. Beyond threshold conditions, patterns merge and we observe film. A simplified theory suggests deforms geometry film, which is...