They are something of a mystery, yet it is possible to manipulate the development of these bubbles, according to PhD candidate Shangjiong Yang at the University of Twente. The bubbles can then, for example, be used to reduce flow resistance in liquids. Yang received his doctorate from the Faculty of Applied Sciences on 9 October.
If a water-repellent material is submerged in water, nanobubbles can develop on its surface: extremely small air bubbles with a diameter of 50-200 nanometres and a thickness of 5-20 nanometres. These bubbles are so small they cannot even be seen with a normal microscope and that is why they were not discovered until a few years ago.
According to existing theories, these bubbles should really not exist at all, as the pressure inside them is so great that the gas they contain should be pressed out within a fraction of a second. It is still not understood why these bubbles can remain intact for hours. Once it is possible to manipulate the formation and properties of these bubbles, a whole range of applications becomes possible. For example, the frictional resistance of flowing liquids is reduced by the bubbles, thus enabling them to be used as a lubricant in extremely narrow channels. This is of practical use in the development of the so-called ‘labs-on-a-chip’: a whole laboratory set-up, reduced to the size of a chip. Before these bubbles can be employed in this way, however, we have to understand them better and be able to determine exactly where they should develop.
Production of nanobubbles
Yang demonstrated that electrolysis is a reliable method for controlling the production of nanobubbles. He discovered a way of influencing the formation and size of the bubbles by applying a voltage. He also researched several fundamental properties of the bubbles. After all, before you can use them you have to understand them. That is why he investigated the influence of temperature, gas concentration, the roughness of the surface and the surface treatment method on bubble formation.
Yang made use of the Atomic Force Microscope (AFM) when carrying out his investigation. It is a microscope with a minuscule needle that moves over the surface (just like the needle of a record player) and monitors differences in height. This needle was used not only to investigate the outlines of the bubbles but also to manipulate them.
Wiebe van der Veen | alfa
What happens when we heat the atomic lattice of a magnet all of a sudden?
18.07.2018 | Forschungsverbund Berlin
Subaru Telescope helps pinpoint origin of ultra-high energy neutrino
16.07.2018 | National Institutes of Natural Sciences
For the first time ever, scientists have determined the cosmic origin of highest-energy neutrinos. A research group led by IceCube scientist Elisa Resconi, spokesperson of the Collaborative Research Center SFB1258 at the Technical University of Munich (TUM), provides an important piece of evidence that the particles detected by the IceCube neutrino telescope at the South Pole originate from a galaxy four billion light-years away from Earth.
To rule out other origins with certainty, the team led by neutrino physicist Elisa Resconi from the Technical University of Munich and multi-wavelength...
For the first time a team of researchers have discovered two different phases of magnetic skyrmions in a single material. Physicists of the Technical Universities of Munich and Dresden and the University of Cologne can now better study and understand the properties of these magnetic structures, which are important for both basic research and applications.
Whirlpools are an everyday experience in a bath tub: When the water is drained a circular vortex is formed. Typically, such whirls are rather stable. Similar...
Physicists working with Roland Wester at the University of Innsbruck have investigated if and how chemical reactions can be influenced by targeted vibrational excitation of the reactants. They were able to demonstrate that excitation with a laser beam does not affect the efficiency of a chemical exchange reaction and that the excited molecular group acts only as a spectator in the reaction.
A frequently used reaction in organic chemistry is nucleophilic substitution. It plays, for example, an important role in in the synthesis of new chemical...
Optical spectroscopy allows investigating the energy structure and dynamic properties of complex quantum systems. Researchers from the University of Würzburg present two new approaches of coherent two-dimensional spectroscopy.
"Put an excitation into the system and observe how it evolves." According to physicist Professor Tobias Brixner, this is the credo of optical spectroscopy....
Ultra-short, high-intensity X-ray flashes open the door to the foundations of chemical reactions. Free-electron lasers generate these kinds of pulses, but there is a catch: the pulses vary in duration and energy. An international research team has now presented a solution: Using a ring of 16 detectors and a circularly polarized laser beam, they can determine both factors with attosecond accuracy.
Free-electron lasers (FELs) generate extremely short and intense X-ray flashes. Researchers can use these flashes to resolve structures with diameters on the...
13.07.2018 | Event News
12.07.2018 | Event News
03.07.2018 | Event News
18.07.2018 | Life Sciences
18.07.2018 | Life Sciences
18.07.2018 | Information Technology