Qin Dui, Yang Qianru, Lei Shuang, Fu Jia, Ji Xiaojuan, Wang Xiuxin
Chongqing Engineering Research Center of Medical Electronics and Information Technology, Department of Biomedical Engineering, School of Bioinformatics, Chongqing University of Posts and Telecommunications, Chongqing, People's Republic of China; Postdoctoral Workstation of Chongqing General Hospital, Chongqing, People's Republic of China.
Chongqing Engineering Research Center of Medical Electronics and Information Technology, Department of Biomedical Engineering, School of Bioinformatics, Chongqing University of Posts and Telecommunications, Chongqing, People's Republic of China.
Ultrason Sonochem. 2023 Oct;99:106586. doi: 10.1016/j.ultsonch.2023.106586. Epub 2023 Sep 4.
The cavitation dynamics of a two-bubble system in viscoelastic media excited by dual-frequency ultrasound is studied numerically with a focus on the effects of inter-bubble interactions. Compared to the isolated bubble cases, the enhancement or suppression effects can be exerted on the amplitude and nonlinearity of the bubble oscillations to different degrees. Moreover, the interaction effects are found to be highly sensitive to multiple paramount parameters related to the two-bubble system, the dual-frequency ultrasound and the medium viscoelasticity. Specifically, the larger bubble of a two-bubble system shows a stronger effect on the smaller one, and this effect becomes more pronounced when the larger bubble undergoes harmonic and/or subharmonic resonances as well as the two bubbles get closer (e.g., d < 100 μm). For the influences of the dual-frequency excitation, the results show that the bubbles can achieve enhanced harmonic and/or subharmonic oscillations as the frequency combinations with small frequency differences (e.g., Δf < 0.2 MHz) close to the corresponding resonance frequencies of bubbles, and the interaction effects are consequently intensified. Similarly, the bubble oscillations and the interaction effects can also be enhanced as the acoustic pressure amplitude of each frequency component is equal and the pressure amplitude p increases. Above a pressure threshold (p = 215 kPa), a larger bubble undergoes period 2 (P2) oscillations, which can force a smaller bubble to change its oscillation pattern from period 1 (P1) into P2 oscillations. In addition, it is found that the medium viscosity dampens the bubble oscillations while the medium elasticity affects the bubble resonances, accordingly exhibiting stronger interaction effects at smaller viscosities (e.g., μ < 4 mPa·s) or certain elasticities (approximately G = 70-120 kPa, G = 160-200 kPa and G = 640-780 kPa) at which the bubble resonances occur. The study can contribute to a better understanding of the complex dynamic behaviors of interacting cavitation bubbles in viscoelastic tissues for high efficient cavitation-mediated biomedical applications using dual-frequency ultrasound.
数值研究了双频超声激发下粘弹性介质中双气泡系统的空化动力学，重点关注气泡间相互作用的影响。与孤立气泡情况相比，气泡振荡的幅度和非线性会受到不同程度的增强或抑制作用。此外，发现相互作用效应对与双气泡系统、双频超声和介质粘弹性相关的多个关键参数高度敏感。具体而言，双气泡系统中较大的气泡对较小的气泡影响更强，当较大气泡发生谐波和/或次谐波共振以及两个气泡靠得更近（例如，d < 100 μm）时，这种影响会更加明显。对于双频激发的影响，结果表明，当频率组合的频率差较小（例如，Δf < 0.2 MHz）且接近气泡的相应共振频率时，气泡可以实现增强的谐波和/或次谐波振荡，相互作用效应也会因此增强。同样，当每个频率分量的声压幅度相等且压力幅度p增加时，气泡振荡和相互作用效应也会增强。在压力阈值（p = 215 kPa）以上，较大的气泡会发生周期2（P2）振荡，这会迫使较小的气泡将其振荡模式从周期1（P1）转变为P2振荡。此外，发现介质粘度会抑制气泡振荡，而介质弹性会影响气泡共振，因此在较小粘度（例如，μ < 4 mPa·s）或某些弹性（大约G = 70 - 120 kPa、G = 160 - 200 kPa和G = 640 - 780 kPa）下，气泡共振发生时会表现出更强的相互作用效应。该研究有助于更好地理解粘弹性组织中相互作用的空化气泡的复杂动态行为，以用于使用双频超声的高效空化介导生物医学应用。
