Linear behavior of a preformed microbubble containing light absorbing nanoparticles: insight from a mathematical...

Area of Science:

• Acoustics and Optics
• Biomedical Engineering
• Nanotechnology

Background:

• Microbubbles are established ultrasonic contrast agents due to efficient scattering.
• Gold nanoparticles effectively absorb optical radiation, generating thermo-acoustic waves.
• Integrating these offers potential for novel imaging modalities.

Purpose of the Study:

• To theoretically and numerically analyze inducing microbubble radial oscillations via laser-excited internal gold nanoparticles.
• To investigate the feasibility of using this system for photoacoustic imaging.
• To determine the optimal frequency range for medical applications.

Main Methods:

• A confined two-phase model describing nanoparticles in gas within a liquid was developed.
• The Rayleigh-Plesset equation governed the gas-liquid boundary dynamics.
• Linear approximation and diagonalization were used to solve the model and obtain general solutions.

Main Results:

• The model predicted exponentially decaying oscillatory functions for internal temperature and pressure.
• Radial oscillations of the microbubble boundary were observed.
• Optimal oscillatory behavior occurred in the low megahertz range for specific bubble sizes.

Conclusions:

• The study demonstrates the theoretical possibility of laser-induced microbubble oscillations.
• This phenomenon holds promise for new applications in photoacoustic imaging.
• The low megahertz oscillation frequency is suitable for medical imaging applications.