Submegahertz Nucleation of Plasmonic Vapor Microbubbles near a Solid Vertical Boundary

Area of Science:

• Physics
• Fluid Dynamics
• Nanotechnology

Background:

• Laser-triggered and photothermally induced vapor bubbles are key for optomechanical energy conversion in microfluidics and nanofluidics.
• Controlling vapor bubble nucleation and behavior is crucial for advanced applications.

Purpose of the Study:

• To investigate the spontaneous, periodic nucleation of plasmonic vapor bubbles near a rigid sidewall.
• To understand the mechanisms governing the repeatable nucleation and collapsing dynamics of these bubbles.
• To develop a model predicting bubble nucleation frequency and stability.

Main Methods:

• Experimental observation of vapor bubble nucleation and dynamics.
• Numerical simulations of bubble collapsing processes.
• Derivation of a mathematical model based on Kelvin impulses and forces.

Main Results:

• Observed spontaneously triggered periodic nucleation of plasmonic vapor bubbles with tunable frequencies (0.8 kHz to >200 kHz).
• Identified lateral migration of residual bubbles refreshing the laser spot as key to repeatable nucleation.
• Developed a model showing competition between Bjerknes force and thermal Marangoni force governs bubble dynamics.
• Established a criterion (γζ<0.34) for repeatable bubble nucleation.

Conclusions:

• Demonstrated high-frequency vapor bubble nucleation for generating strong localized flows in micro/nanofluidics.
• The findings provide a method for remote control of fluid dynamics using light.
• The derived model offers predictive capabilities for controlling vapor bubble behavior.