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


Features

More Features »

Subject Areas

NanophysicsFluid Dynamics

Previous Synopsis

Next Synopsis

Fluid Dynamics

Convection Speeds Up on a Slant

Read More »

Related Articles

Focus: Fluid Interactions Help Fish in a School Swim Faster
Fluid Dynamics

Focus: Fluid Interactions Help Fish in a School Swim Faster

Simulations of fish schools that include fluid dynamics in addition to the usual coordination of individuals lead to faster swimmers and reveal a new collective swimming mode. Read More »

Synopsis: Thermal Radiation Gets a Boost
Nanophysics

Synopsis: Thermal Radiation Gets a Boost

The thermal radiation transfer between two quartz plates separated by a 200-nm gap is 45 times greater than predicted by conventional laws for blackbodies. Read More »

Synopsis: Transition to Superlubricity in 2D
Fluid Dynamics

Synopsis: Transition to Superlubricity in 2D

Studying particles sliding over a 2D potential lattice, researchers have observed a phase transition between a frictional regime and a frictionless, “superlubric” regime Read More »

More Articles