Traces of Nanobubbles Determine Nano-boiling

This clip in dv format.
This clip in avi format.

This clip in dv format.
This clip in avi format.

This clip in dv format.
This clip in avi format.

This clip in dv format.
This clip in avi format.

DV clips require QuickTime, a free download – click here.
AVI clips require Windows Media Player (or equivalent), a free download – click here.

First Nucleation: This clip shows bubble nucleation during the first pulse of a two-pulse sequence. The first frame is at a delay of 3.5 microseconds from the start of the voltage pulse. Succeeding frames are 10 ns apart. Note that although each frame is from a different bubble nucleation event, the images appear to be the steady growth of a single bubble, demonstrating the reproducibility of bubble growth during the first pulse.

Growth and Collapse: during the first pulse of a two-pulse sequence. The first frame is at a delay of 3.5 microseconds from the start of the voltage pulse. Succeeding frames are 50 ns apart.

Second Nucleation: This clip shows bubble nucleation during the second pulse of a two-pulse sequence. The first frame is at a delay of 1.8 microseconds from the start of the voltage pulse. Succeeding frames are 10 ns apart. When measured from the start of their respective voltage pulses, bubbles from the second pulse appear 1.7 microseconds earlier than for the case of the first pulse. Note that because each frame is from a different bubble nucleation event, the growth process seems chaotic when viewed as a movie. This is evidence for the nature of the occurrence of the nucleation sites—nanobubbles formed at scattered locations from the collapse of the bubble from the first pulse.

Growth and Collapse: during the second pulse of a two-pulse sequence. The first frame is at a delay of 1.8 microseconds from the start of the voltage pulse. Succeeding frames are 50 ns apart.

Tracing the Effects of Nanobubbles
This series of four video clips (in dv format) shows how the presence of nanobubbles affects the growth of microbubbles on a microheater. Each frame of each “movie” actually is from a different bubble nucleation and growth process. Each frame is taken after a set delay from the start of the voltage pulse to the heater. The frames are assembled into a movie in the order of increasing delay times. The flash duration of the laser is 7.5 nanoseconds. The distance across the microheater (top to bottom) is about 15 micrometers.

While the bubbles formed by the first pulse in the series are very repeatable—so much so that it almost looks like a movie of a single bubble—the bubbles formed by the second pulse are much more chaotic because their nucleation is affected by unseen residual nanobubbles on the microheater.

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