Multi-Microseconds Microbubbles Induced by Nanoseconds Pulsed-Laser Heating of Gold Nano-Particles

Area of Science:

• Nanotechnology
• Physical Chemistry
• Fluid Dynamics

Background:

• Gold nanoparticles (GNPs) are utilized in various applications due to their unique optical properties.
• Laser-induced bubble formation is a key phenomenon in fields like sonochemistry and biomedical engineering.
• Understanding microbubble dynamics is crucial for optimizing laser-based technologies.

Purpose of the Study:

• To investigate the impact of gold nanoparticle aggregation on water-vapor microbubble (WV-MB) formation and dynamics.
• To differentiate the contributions of water-vapor phase change and dissolved gas release to microbubble lifecycles.
• To explore the potential of prolonged WV-MBs for advanced applications.

Main Methods:

• High-speed visualization at 216 kfps to capture microbubble evolution.
• Employing a double-exponential function to model distinct growth and collapse phases.
• Numerical modeling of heat diffusion around plasmonically heated GNPs.
• Investigating the correlation between nanoparticle aggregation and microbubble characteristics.

Main Results:

• Microbubble formation exhibits a dual-nature system: rapid water-vapor (WV) growth/collapse (multimicroseconds) followed by slow dissolved gas (DG) release-driven collapse (>milliseconds).
• Nanoparticle aggregation significantly influences the prolonged WV lifetime, deviating from previously reported nanosecond scales.
• A negative correlation exists between WV lifetime and DG contribution, with increased aggregation leading to shorter WV lifetimes.

Conclusions:

• Gold nanoparticle aggregation can enhance or suppress plasmonic bubble generation and modulate WV lifetime and DG release.
• The study demonstrates the feasibility of generating multimicrosecond WV-MBs.
• These findings offer potential for extended operational windows in imaging, diagnostics, therapeutics, and microfluidics.