Related Experiment Videos
Prediction of rectified diffusion during nonlinear bubble pulsations at biomedical frequencies
1Department of Biophysics, School of Medicine and Dentistry, University of Rochester, New York 14642.
The Journal of the Acoustical Society of America
|June 1, 1988
Summary
Rectified diffusion in biomedical ultrasound shows small bubbles grow to resonance size only in narrow frequency ranges. Growth rates can be high at medically relevant pressures, with thresholds sensitive to gas concentration.
Area of Science:
- Acoustics
- Biomedical Engineering
- Fluid Dynamics
Background:
- Rectified diffusion is a key mechanism for bubble growth in ultrasound.
- Previous models often simplify bubble dynamics and diffusion processes.
Purpose of the Study:
- To investigate bubble growth and collapse dynamics via rectified diffusion in the biomedical frequency range (1-10 MHz).
- To calculate growth rates and thresholds under medically relevant conditions.
Main Methods:
- Combined Gilmore-Akulichev formulation for bubble dynamics with Eller-Flynn approach for rectified diffusion.
- Conducted computer simulations across the 1-10 MHz frequency spectrum.
Main Results:
- The common belief of bubble growth to resonance size and violent collapse is only true for limited bubble ranges above 1 MHz.
- High growth rates (approx. 20 micron/s at 1 MHz, 1 bar) are possible at medically relevant pressures.
- Analytical thresholds are accurate at low frequencies but only near resonance radius at high frequencies.
- Thresholds demonstrate significant sensitivity to dissolved gas concentration at low frequencies.
Conclusions:
- Bubble behavior under rectified diffusion is more complex than previously assumed, especially at higher frequencies.
- The study provides crucial data for understanding ultrasound-mediated biological effects and optimizing therapeutic applications.
- Accurate modeling of bubble dynamics is essential for predicting outcomes in biomedical ultrasound.