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Lecture

Surface Tension: Fundamentals and Applications

In course

MICRO-301: Manufacturing technologies

This course gives an introduction to production methods and manufacturing technologies used in microengineering. The focus is given on the understanding of physical phenomena underlying the processes, the relation between materials, manufacturing processes ...

Description

This lecture covers the fundamentals of surface tension, including the wettability of surfaces, vapor pressure, contact angles, and engineered hydrophobic surfaces. It also delves into adhesion forces, models of adhesion, and the impact of contact angles on vapor pressure. The lecture explores the Laplace-Young equation, capillary forces, electrostatic forces, Van der Waals forces, and their integrated forms for various geometries. Additionally, it discusses the adhesion force comparison, laser micromachining, and the role of surfaces in affecting physical properties of objects. The lecture concludes with a discussion on laser manufacturing technologies, including cutting, additive manufacturing, and laser eye surgery.

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Instructors (2)

Vivek Subramanian

Yves Bellouard

Dr. Yves Bellouard is Associate Professor in Microengineering at Ecole Polytechnique Fédérale de Lausanne (EPFL) in Switzerland, where he heads the Galatea lab and the Richemont Chair in micromanufacturing. He received a BS in Theoretical Physics and a MS in Applied Physics from Université Pierre et Marie Curie in Paris, France in 1994-1995 and a PhD in Microengineering from Ecole Polytechnique Fédérale de Lausanne (EPFL) in Lausanne, Switzerland in 2000. For his PhD work, he received the Omega Scientific prize (2001) for outstanding contribution in the field of microengineering for his work on Shape Memory Alloys. Before joining EPFL in 2015, he was Associate Professor at Eindhoven University of Technologies (TU/e) in the Netherlands and prior to that, Research Scientist at Rensselaer Polytechnic Institute (RPI) in Troy, New York for about four years where he started working on femtosecond laser processing of glass materials. From 2010 until 2013, Yves Bellouard initiated and coordinated the Femtoprint project, a European research initiative aiming at investigating a table-top printer for microsystems ('3D printing of microsystems'). In 2013, he received a prestigious ERC Starting Grant (Consolidator-2012) from the European Research Council and a JSPS Fellowship from the Japan Society for the Promotion of Science. His current research interests are on new paradigms for system integration at the microscale and in particular laser-based methods to tailor material properties for achieving higher level of integration in microsystems, like for instance integrating optics, mechanics and fluidics in a single monolith. These approaches open new opportunities for direct-write methods of microsystems (3D printing). Personal website

Official source

Ontological neighbourhood

Chemistry

Physical chemistry: Surface science

Related concepts (32)

Surface tension

Surface tension is the tendency of liquid surfaces at rest to shrink into the minimum surface area possible. Surface tension is what allows objects with a higher density than water such as razor blades and insects (e.g. water striders) to float on a water surface without becoming even partly submerged. At liquid–air interfaces, surface tension results from the greater attraction of liquid molecules to each other (due to cohesion) than to the molecules in the air (due to adhesion). There are two primary mechanisms in play.

Van der Waals force

In molecular physics, the van der Waals force is a distance-dependent interaction between atoms or molecules. Unlike ionic or covalent bonds, these attractions do not result from a chemical electronic bond; they are comparatively weak and therefore more susceptible to disturbance. The van der Waals force quickly vanishes at longer distances between interacting molecules. Named after Dutch physicist Johannes Diderik van der Waals, the van der Waals force plays a fundamental role in fields as diverse as supramolecular chemistry, structural biology, polymer science, nanotechnology, surface science, and condensed matter physics.

Wetting

Wetting is the ability of a liquid to maintain contact with a solid surface, resulting from intermolecular interactions when the two are brought together. This happens in presence of a gaseous phase or another liquid phase not miscible with the first one. The degree of wetting (wettability) is determined by a force balance between adhesive and cohesive forces. Wetting is important in the bonding or adherence of two materials. Wetting and the surface forces that control wetting are also responsible for other related effects, including capillary effects.

Surface energy

In surface science, surface free energy (also interfacial free energy or surface energy) quantifies the disruption of intermolecular bonds that occurs when a surface is created. In solid-state physics, surfaces must be intrinsically less energetically favorable than the bulk of the material (the atoms on the surface have more energy compared with the atoms in the bulk), otherwise there would be a driving force for surfaces to be created, removing the bulk of the material (see sublimation).

Capillary length

The capillary length or capillary constant, is a length scaling factor that relates gravity and surface tension. It is a fundamental physical property that governs the behavior of menisci, and is found when body forces (gravity) and surface forces (Laplace pressure) are in equilibrium. The pressure of a static fluid does not depend on the shape, total mass or surface area of the fluid. It is directly proportional to the fluid's specific weight – the force exerted by gravity over a specific volume, and its vertical height.

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