Synopsis: Can’t Burst This Bubble

A new theory attempts to explain the exceptionally long life of air nanobubbles on wet surfaces.
Synopsis figure
Courtesy Michiel van Limbeek and Joost H. Weijs/University of Twente

How long an air bubble lives in water depends critically on its size. Because of surface tension, the smaller the radius of curvature of the bubble, the easier it is for the bubble to leak gas and collapse. Bubbles smaller than 100 nanometers in diameter should last less than a few microseconds. However, recent observations show that on a solid surface covered by water, nanobubbles can live as much as ten orders of magnitude longer than free bubbles (up to days). No satisfactory explanation for this property has been found, but now, writing in Physical Review Letters, Joost H. Weijs and Detlef Lohse at the University of Twente in the Netherlands claim to have solved this riddle.

The authors’ theory is based on conventional diffusion physics but accounts for the specificity of the surface bubble geometry. Two effects play a major role in the model. First, as the bubbles leak gas, they stick to the same area on the surface and get thinner and flatter. The radius of curvature thus increases, making them more stable. Second, a sort of “traffic jam” effect occurs: Since the liquid is typically saturated with gas, an individual bubble can only leak its gas into the liquid if a corresponding amount of gas is released into the atmosphere. This dramatically reduces the speed at which the gas can leave the bubble.

The theory yields lifetimes consistent with previous observations. Should it be validated by further experimental tests, the model may assist a vast array of applications. These range from the transport of anticancer drugs across biological membranes to friction-reduction in nanofluidic devices, where nanobubble coatings could be deposited on the surface of nanochannels to facilitate the passage of fluids. – Matteo Rini


Announcements

More Announcements »

Subject Areas

NanophysicsFluid Dynamics

Previous Synopsis

Next Synopsis

Fluid Dynamics

Convection Speeds Up on a Slant

Read More »

Related Articles

Focus: Surface Waves Store Bouncing Droplet’s History
Nonlinear Dynamics

Focus: Surface Waves Store Bouncing Droplet’s History

A droplet bouncing and wandering across a liquid surface can produce waves that store the history of its chaotic motion. Read More »

Viewpoint: How to Fracture a Fluid
Fluid Dynamics

Viewpoint: How to Fracture a Fluid

High-speed imaging shows that fluids can break like brittle glass under the right conditions. Read More »

Synopsis: So Many Cracks, So Little Time
Fluid Dynamics

Synopsis: So Many Cracks, So Little Time

Water droplets impacting a cold surface exhibit a variety of fracture patterns depending on the temperature of the surface. Read More »

More Articles