Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

’Armored’ bubbles can exist in stable non-spherical shapes

15.12.2005


Coating of tightly packed particles on bubble surface supports stresses to stabilize shape

Researchers at Harvard University have demonstrated that gas bubbles can exist in stable non-spherical shapes without the application of external force. The micron- to millimeter scale peapod-, doughnut- and sausage-shaped bubbles, created by coating ordinary gas bubbles with a tightly packed layer of tiny particles and then fusing them, are described this week on the web site of the journal Nature.

"Particles have been used to stabilize emulsions and foams for over 100 years," says lead author Anand Bala Subramaniam, a research associate in Harvard’s Division of Engineering and Applied Sciences who conducted much of the work before receiving his undergraduate degree from Harvard College last June. "However, we’ve demonstrated that not only are particles useful for making bubbles last longer, they fundamentally alter the properties of these bubbles. Instead of behaving like a fluid surface that flows to balance unequal stresses, the ’armor’ of particles on the surface of the bubbles actually supports the unequal stresses inherent in non-spherical shapes."



Surface tension gives all bubbles and drops their perfectly spherical shape by minimizing the surface area for a given volume. Ordinarily if two bubbles are fused, the product is a larger but still spherical bubble. But when particles are strongly anchored to the bubble surface and the bubbles are fused, a stable sausage shape is produced.

"The bubble wants to reduce its surface area by going back to a spherical shape, but the strong anchoring of the particles on the surface prevents their expulsion," Bala Subramaniam says. "The particles end up tightly packed, and eventually push against each other strongly, allowing the bubble surface to carry forces to support a non-spherical shape."

Although the particles are jammed, they are not bonded to each other, Bala Subramaniam adds. It is this absence of permanent bonds that allowed the researchers to reshape and remold the initially sausage-shaped bubbles into peapods, disks and donuts.

The phenomenon of irregularly shaped bubbles has been observed in nature; air bubbles in impure ocean water are often non-spherical, their shapes distorted by surface dirt. The concepts of jamming and non-spherical shapes may also be useful for understanding other systems such as biological membranes. Bala Subramaniam and his colleagues have found particle jamming on surfaces to be a general phenomenon compatible with a wide range of particle coatings, including polystyrene, polymethylmethacrylate, gold and zirconium oxide. Both particle and bubble size can vary widely, with the largest armored bubbles roughly 10,000 times the size of the smallest.

"We have provided a general explanation of why these non-spherical bubbles can be observed," says co-author Howard A. Stone, Bala Subramaniam’s advisor and the Vicky Joseph Professor of Engineering and Applied Mathematics at Harvard. "Bubbles are engineered into many consumer products. The ability to alter the shapes of bubbles and liquid drops in products like ice cream or shaving foams or creams may provide a means to alter the consistency or texture of these products. The non-spherical bubbles could also find use as vessels for delivering drugs, vitamins or flavors."

Steve Bradt | EurekAlert!
Further information:
http://www.harvard.edu

More articles from Life Sciences:

nachricht Topologische Quantenchemie
21.07.2017 | Max-Planck-Institut für Chemische Physik fester Stoffe

nachricht Topological Quantum Chemistry
21.07.2017 | Max-Planck-Institut für Chemische Physik fester Stoffe

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Manipulating Electron Spins Without Loss of Information

Physicists have developed a new technique that uses electrical voltages to control the electron spin on a chip. The newly-developed method provides protection from spin decay, meaning that the contained information can be maintained and transmitted over comparatively large distances, as has been demonstrated by a team from the University of Basel’s Department of Physics and the Swiss Nanoscience Institute. The results have been published in Physical Review X.

For several years, researchers have been trying to use the spin of an electron to store and transmit information. The spin of each electron is always coupled...

Im Focus: The proton precisely weighted

What is the mass of a proton? Scientists from Germany and Japan successfully did an important step towards the most exact knowledge of this fundamental constant. By means of precision measurements on a single proton, they could improve the precision by a factor of three and also correct the existing value.

To determine the mass of a single proton still more accurate – a group of physicists led by Klaus Blaum and Sven Sturm of the Max Planck Institute for Nuclear...

Im Focus: On the way to a biological alternative

A bacterial enzyme enables reactions that open up alternatives to key industrial chemical processes

The research team of Prof. Dr. Oliver Einsle at the University of Freiburg's Institute of Biochemistry has long been exploring the functioning of nitrogenase....

Im Focus: The 1 trillion tonne iceberg

Larsen C Ice Shelf rift finally breaks through

A one trillion tonne iceberg - one of the biggest ever recorded -- has calved away from the Larsen C Ice Shelf in Antarctica, after a rift in the ice,...

Im Focus: Laser-cooled ions contribute to better understanding of friction

Physics supports biology: Researchers from PTB have developed a model system to investigate friction phenomena with atomic precision

Friction: what you want from car brakes, otherwise rather a nuisance. In any case, it is useful to know as precisely as possible how friction phenomena arise –...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Closing the Sustainability Circle: Protection of Food with Biobased Materials

21.07.2017 | Event News

»We are bringing Additive Manufacturing to SMEs«

19.07.2017 | Event News

The technology with a feel for feelings

12.07.2017 | Event News

 
Latest News

NASA looks to solar eclipse to help understand Earth's energy system

21.07.2017 | Earth Sciences

Stanford researchers develop a new type of soft, growing robot

21.07.2017 | Power and Electrical Engineering

Vortex photons from electrons in circular motion

21.07.2017 | Physics and Astronomy

VideoLinks
B2B-VideoLinks
More VideoLinks >>>