包膜黏弹特性及声驱动参数对相互作用微泡动力学行为的影响

关于多气泡相互作用的理论研究对于深入理解超声造影剂在医疗领域中的应用机理具有重要意义。本工作建立了一个2维轴对称有限元模型来研究流体环境中超声造影剂双气泡相互作用,讨论了驱动超声频率和气泡尺寸对气泡之间吸引和排斥趋势的影响,得到了气泡半径与气泡之间距离随时间变化的曲线,以及气泡周围流体速度场的细节,并且研究了气泡包膜参数(即表面张力系数和粘度系数)对气泡相互作用的影响.结果表明,相互作用中的气泡对整体的相对运动趋势由驱动频率和共振频率之间的关系决定;在超声参数固定时,气泡包膜的粘弹特性可用来调控气泡间相互作用强度。结果对实验中观察到的气泡聚集现象进行了合理解释,并为超声造影剂在医疗实践中的应用提供了基础理论支撑. 

The impacts of encapsulating shell properties and acoustic driving parameters on the dynamic behavior of interacting microbubbles

Theoretical studies on the dynamic interactions between multi-bubbles is a key topic for better understanding the physical mechanisms underlying clinical applications of Ultrasound Contrast Agents(UCAs).In the present work,a2-D axisymmetric Finite Element Model(FEM) was developed to investigate the bubble-bubble interactions for UCAs in an infinite fluidic environment.The impacts of acoustic driving parameters and the bubble size on the bubble interaction tendency were discussed,as well as the influences of bubble shell mechanical parameters.In addition,the temporal evolution of the bubbles' radii,the distance between bubbles' center,and the distribution of the velocity field in the surrounding fluid were also investigated based on FEM simulations.The results indicated that,for the interacting bubbles,the overall translational tendency should be dominated by the relationship between the driving frequency and their resonance frequencies.For constant acoustic driving parameters,the bubble-bubble interactions could be regulated by adjusting the shell visco-elasticity coefficients of the bubbles.The current work should be beneficial for in-depth understanding of the theoretical fundamentals behind bubble-bubble interactions,which plays an important role in the controlling and optimization of UCA applications.