A way to create liquid droplets inside of air bubbles

February 8, 2018 by Bob Yirka, Phys.org report
(a) Drop encapsulated in bubble, which is the last unknown area in the fluid encapsulation map. (b) Diagram of the experiment setup. (c) Stable production of uniform capsules (see Supplemental Material for the multimedia view). Credit: Physical Review Letters (2018). DOI: 10.1103/PhysRevLett.120.054503

A team of researchers at Zhejiang University in China has developed a technique to create liquid droplets inside of air bubbles. In their paper published in the journal Physical Review Letters, the group describes the technique and some possible commercial applications.

Physicists study bubbles and droplets because of the unique processes involved, and because doing so has led to the development of many useful applications such as . In this new effort, the researchers applied known properties of glycerol-water solutions in a unique way to generate liquid-suspended air bubbles containing a liquid drop inside of them.

To create such bubbles, the researchers forced small amounts of alternating liquid and air through a tube into a tank filled with a , causing the generation of a so-called "Taylor flow," alternating "slugs" of liquid and . When an air bubble entered the tank, it was forced off the nozzle by the slug behind it—and when the conditions were just right, the team reports, that push by the slug forced a droplet into the air bubble, which then persisted in the solution for a length of time—the drop was released when the bubble encountered a solid surface, i.e., ran into the side of the tank. The team refers to their creation as a "drop encapsulated in a bubble."

The group further reports that for encapsulation to occur, the ratio of surface tension on the bubble to the degree of viscosity must be at a certain point as must the height to width ratio of the slug as it begins to make its way into the bubble. They note also that the drop inside the bubble showed an ability to withstand sheer flow. They suggest the technique could lead to the development of new ways to deliver medications or a means for processing materials in a manufacturing environment. One example, they point out, would be a novel way to create capsules of different sizes. They also note that it could be used as a means of fluid transport.

Explore further: A model explains effects like the formation of clouds from the sea

More information: Yingnan Shen et al. Drop Encapsulated in Bubble: A New Encapsulation Structure, Physical Review Letters (2018). DOI: 10.1103/PhysRevLett.120.054503

A new fluid encapsulation structure, which is characterized by a bubble encapsulating a drop, is reported. It is stably generated from the breakup of a liquid column inside a bubble, which is achieved via the injection of Taylor flow into liquid. A model is constructed to explain the liquid column breakup mechanism. A dimensionless control guidance, which enables the possibility to create different-scale capsules, is provided. The encapsulation stability in external flows is verified, and a method to trigger the release of the encapsulated drop is provided, which supports potential applications with great advantages such as fluid transport.

Related Stories

New bubbling mechanism discovered in physics

April 11, 2017

A group of researchers at Zhejiang University's State Key Laboratory of Fluid Power and Mechatronic Systems, in Hangzhou, China, recently discovered that a new bubbling mechanism may exist within the realm of physics.

Soap bubbles' secrets go pop

February 23, 2016

Some phenomena that appear to be well understood are much more mysterious than it seems. In spite of the numerous applications that rely on the presence or absence of bubbles, no advanced scientific studies had been carried ...

Recommended for you

Physicists reveal why matter dominates universe

March 21, 2019

Physicists in the College of Arts and Sciences at Syracuse University have confirmed that matter and antimatter decay differently for elementary particles containing charmed quarks.

ATLAS experiment observes light scattering off light

March 20, 2019

Light-by-light scattering is a very rare phenomenon in which two photons interact, producing another pair of photons. This process was among the earliest predictions of quantum electrodynamics (QED), the quantum theory of ...

How heavy elements come about in the universe

March 19, 2019

Heavy elements are produced during stellar explosion or on the surfaces of neutron stars through the capture of hydrogen nuclei (protons). This occurs at extremely high temperatures, but at relatively low energies. An international ...


Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.