Zhao Yubo, Feng Yi, Wu Liang
The Key Laboratory of Biomedical Information Engineering of Ministry of Education, Department of Biomedical Engineering, School of Life Science and Technology, Xi'an Jiaotong University, Xi'an, People's Republic of China.
The Key Laboratory of Biomedical Information Engineering of Ministry of Education, Department of Biomedical Engineering, School of Life Science and Technology, Xi'an Jiaotong University, Xi'an, People's Republic of China.
Ultrason Sonochem. 2024 Mar;104:106848. doi: 10.1016/j.ultsonch.2024.106848. Epub 2024 Mar 12.
Dual-frequency ultrasound has been widely employed to enhance and regulate acoustic droplet vaporization (ADV) but the role of ultrasonic nonlinear effects on it remains unclear. The main objective of this study is to investigate the influence of nonlinear effects on the control of ADV nucleation under different dual-frequency focused ultrasound conditions. ADV nucleation of PFC nanodroplets activated by nonlinear dual-frequency ultrasound was modeled and parametric studies were conducted to investigate the influence of dual-frequency ultrasound frequency and acoustic power on the degree of nonlinearity (DoN), nucleation rates and dimensions of the nucleation region in a wide parameter range. The results showed that the ultrasonic nonlinearity caused a significant decrease in peak negative pressure due to waveform distortion, which leads to a lower nucleation rate in the nonlinear model compared to that in the linear model. Furthermore, the distributions of nucleation regions were also affected by the interaction between waves of different frequencies and cloud-like spatial distributions were produced, which could be modulated by the dual-frequency ultrasound parameters and have great potentials in the spatial regulation of the ADV and customized treatment protocols in clinical applications. In addition, represented by 1.5 MHz + 3 MHz, such a dual-frequency combination of fundamental and second harmonic could effectively enhance ultrasonic nonlinear effects with relatively lower peak negative pressure and higher DoN. Therefore, nonlinear effect of the dual-frequency ultrasound plays an important role in the ADV regulation, which should be considered in the numerical model and practical applications.
双频超声已被广泛用于增强和调节声滴汽化(ADV),但其超声非线性效应对此的作用仍不清楚。本研究的主要目的是探讨非线性效应对不同双频聚焦超声条件下ADV成核控制的影响。对非线性双频超声激活的全氟碳纳米液滴的ADV成核进行了建模,并进行了参数研究,以研究在较宽参数范围内双频超声频率和声功率对非线性度(DoN)、成核速率和成核区域尺寸的影响。结果表明,超声非线性由于波形失真导致峰值负压显著降低,这使得非线性模型中的成核速率低于线性模型。此外,成核区域的分布也受到不同频率波之间相互作用的影响,并产生云状空间分布,这种分布可由双频超声参数调节,在ADV的空间调节和临床应用中的定制治疗方案方面具有巨大潜力。此外,以1.5MHz + 3MHz为代表,这种基波和二次谐波的双频组合可以在相对较低的峰值负压和较高的DoN下有效增强超声非线性效应。因此,双频超声的非线性效应对ADV调节起着重要作用,在数值模型和实际应用中应予以考虑。