We have obtained interfacial properties of Galinstan, a nontoxic liquid-metal alloy, to help replace mercury in miniature devices. To prevent formation of an oxide skin that severely hinders the ...fluidic behavior of small Galinstan droplets and leads to inaccurate property data, we performed our experiments in a nitrogen-filled glove box. It was found that only if never exposed to oxygen levels above 1 part per million (ppm) would Galinstan droplets behave like a liquid. Two key properties were then investigated: contact angles and surface tension. Advancing and receding contact angles of Galinstan were measured from sessile droplets on various materials: for example, 146.8 and 121.5, respectively, on glass. Surface tension was measured by the pendant-drop method to be 534.6 10.7 mN/m. All the measurements were done in nitrogen at 28 with oxygen and moisture levels below 0.5 ppm. To help design droplet-based microfluidic devices, we tested the response of Galinstan to electrowetting-on-dielectric actuation.
The importance of stress and strain effects on surface physics are reviewed. For this purpose the following points are developed. (1) The elastic, thermodynamics and atomistic definitions of surface ...stress and surface strain are presented in a complementary way so that the surface stress and surface strain concepts based on a proper definition of surface elastic energy in terms of excess quantities are presented in depth. This leads to a natural link between surface stress and surface energy known as Shuttleworth’s relation. (2) The elastic description of surface defects as adatoms, steps, undulation, 2D and 3D islands are reviewed in the framework of elastic point forces concept then partially discussed in terms of forces distribution. (3) As an application, thermodynamics and kinetics description of elastic driven instabilities are reviewed with a particular emphasis on spontaneous Asaro–Tiller–Grienfeld morphological instability, Stranski–Krastanov transition and Marchenko–Andreev domains formation. Some examples are thus described and discussed for pure material as well as for alloys. (4) In case of vicinal faces, step bunching and step meandering instabilities driven by elasticity are rationalised and discussed in a quite complementary way. In particular it is shown how step–step interaction and/or step–adatom interaction may lead to kinetics instabilities. (5) Strain effects on diffusion are discussed. (6) Elasticity effect on some surface phase transition as surface melting or surface roughening are discussed in quite simple model. In case of surface melting of epitaxial layers, new phenomenon as boosted premelting is then predicted. (7) Experimental examples of elasticity as a tool for self-organisation are thus presented.
This is the first book to provide a comprehensive and state-of-the-art introduction to the novel and fast-evolving topic of in-situ produced cosmogenic nuclides. It presents an accessible ...introduction to the theoretical foundations, with explanations of relevant concepts starting at a basic level and building in sophistication. It incorporates, and draws on, methodological discussions and advances achieved within the international CRONUS (Cosmic-Ray Produced Nuclide Systematics) networks. Practical aspects such as sampling, analytical methods and data-interpretation are discussed in detail and an essential sampling checklist is provided. The full range of cosmogenic isotopes is covered and a wide spectrum of in-situ applications are described and illustrated with specific and generic examples of exposure dating, burial dating, erosion and uplift rates and process model verification. Graduate students and experienced practitioners will find this book a vital source of information on the background concepts and practical applications in geomorphology, geography, soil-science, and geology.
Building on advances in miniaturization and soft matter, surface tension effects are a major key to the development of soft/fluidic microrobotics. Benefiting from scaling laws, surface tension and ...capillary effects can enable sensing, actuation, adhesion, confinement, compliance, and other structural and functional properties necessary in micro- and nanosystems.
Various applications are under development: microfluidic and lab-on-chip devices, soft gripping and manipulation of particles, colloidal and interfacial assemblies, fluidic/droplet mechatronics. The capillary action is ubiquitous in drops, bubbles and menisci, opening a broad spectrum of technological solutions and scientific investigations. Identified grand challenges to the establishment of fluidic microrobotics include mastering the dynamics of capillary effects, controlling the hysteresis arising from wetting and evaporation, improving the dispensing and handling of tiny droplets, and developing a mechatronic approach for the control and programming of surface tension effects.
In this Special Issue of Micromachines, we invite contributions covering all aspects of microscale engineering relying on surface tension. Particularly, we welcome contributions on fundamentals or applications related to:
Drop-botics: fluidic or surface tension-based micro/nanorobotics: capillary manipulation, gripping, and actuation, sensing, folding, propulsion and bio-inspired solutions;
Control of surface tension effects: surface tension gradients, active surfactants, thermocapillarity, electrowetting, elastocapillarity;
Handling of droplets, bubbles and liquid bridges: dispensing, confinement, displacement, stretching, rupture, evaporation;
Capillary forces: modelling, measurement, simulation;
Interfacial engineering: smart liquids, surface treatments;
Interfacial fluidic and capillary assembly of colloids and devices;
Biological applications of surface tension, including lab-on-chip and organ-on-chip systems.
We expect novel as well as review contributions on all aspects of surface tension-based micro/nanoengineering. In line with Micromachines' policy, we also invite research proposals that introduce ideas for new applications, devices, or technologies.
This book collects the articles published in the Special Issue “Polymeric Materials: Surfaces, Interfaces and Bioapplications”. It shows the advances in polymeric materials, which have tremendous ...applications in agricultural films, food packaging, dental restoration, antimicrobial systems, and tissue engineering. These polymeric materials are presented as films, coatings, particles, fibers, hydrogels, or networks. The potential to modify and modulate their surfaces or their content by different techniques, such as click chemistry, ozonation, breath figures, wrinkle formation, or electrospray, are also explained, taking into account the relationship between the structure and properties in the final application. Moreover, new trends in the development of such materials are presented, using more environmental friendly and safe methods, which, at the same time, have a high impact on our society.
Due to inspiration from the Nepenthes pitcher plant, a frontier of devices has emerged with unmatched capabilities. Liquid-infused surfaces (LISs), particularly known for their liquid-repelling ...behavior under low tilting angles (<5°), have demonstrated a plethora of applications in medical, marine, energy, industrial, and environmental materials. This review presents recent developments of LIS technology and its prospective to define the future direction of this technology in solving tomorrow’s real-life challenges. First, an introduction to the different models explaining the physical phenomena of these surfaces, their wettability, and viscous-dependent frictional forces is discussed. Then, an outline of different emerging strategies required to fabricate a stable liquid-infused interface is presented, including different substrates, lubricants, surface chemistries, and design parameters which can be tuned depending on the application. Furthermore, applications of LIS coatings in the areas of anticorrosion, antifouling, anti-icing, self-healing, droplet manipulation, and biomedical devices will be presented followed by the limitations and future direction of this technology.
Nanotextured superhydrophobic surfaces have received significant attention due to their ability to easily shed liquid drops. However, water droplets have been shown to condense within the textures of ...superhydrophobic surfaces, impale the vapor pockets, and strongly pin to the surface. This results in poor droplet mobility and degrades condensation performance. In this paper, we show that pinning of condensate droplets can be drastically reduced by designing a hierarchical micro-nanoscale texture on a surface and impregnating it with an appropriate lubricant. The choice of lubricant must take into account the surface energies of all phases present. A lubricant will cloak the condensate and inhibit growth if the spreading coefficient is positive. If the lubricant does not fully wet the solid, we show how condensate–solid pinning can be reduced by proper implementation of nanotexture. On such a surface, condensate droplets as small as 100 μm become highly mobile and move continuously at speeds that are several orders of magnitude higher than those on identically textured superhydrophobic surfaces. This remarkable mobility produces a continuous sweeping effect that clears the surface for fresh nucleation and results in enhanced condensation.
The measurement and characterisation of surface topography is crucial to modern manufacturing industry. The control of areal surface structure allows a manufacturer to radically alter the ...functionality of a part. Examples include structuring to effect fluidics, optics, tribology, aerodynamics and biology. To control such manufacturing methods requires measurement strategies. There is now a large range of new optical techniques on the market, or being developed in academia, that can measure areal surface topography. Each method has its strong points and limitations. The book starts with introductory chapters on optical instruments, their common language, generic features and limitations, and their calibration. Each type of modern optical instrument is described (in a common format) by an expert in the field. The book is intended for both industrial and academic scientists and engineers, and will be useful for undergraduate and postgraduate studies.
Transparent materials such as glasses and some polymers play an essential role in our daily life. Indeed, it is well known that their application in mirrors, windows, automobile windshields, and ...eyewear make our day-to-day activities more comfortable. These examples aside, many more can also be found in several spheres of human activity, including such sectors as diverse and distinct as the medical, photovoltaic and food industry fields. Unfortunately, due to the unavoidable condensation of water vapor on solid surfaces, these materials undergo fogging under normal operating conditions. More than a mere nuisance, this naturally occurring phenomenon adversely affects their optical performance as it lowers the light-transmitting capability and often gives rise to esthetical, hygienic, and safety concerns. In this context, research in the field of anti-fogging technology has attracted growing interest, particularly in recent years, for numerous potential applications. In this review, recent developments in the design and manufacturing of anti-fogging surfaces are described in detail, beginning with the fogging mechanism in terms of nucleation and growth of water drops. Anti-fogging strategies explored thus far and mainly focusing on hydrophilic and hydrophobic surfaces are then extensively described. Finally, based on current research in this promising field, future trends and prospects for their effective implementation are presented.
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