声致液汽相变动力学的理论建模及实验研究

Acoustic droplet vaporization (ADV), a process of making using of ultrasound to phase-transition superheated liquid droplets into gas bubbles, has attracted increasing attention in recent years. By taking advantage of its smaller size, the droplets can pass through capillary beds easily, which could open more promising possibilities in the applications of ultrasound imaging, targeted gene/drug delivery and ultrasound therapy. The current project will focus on both theoretical and experimental investigations of ultrasound-induced droplet-to-bubble transition dynamics. Firstly, a Shan-Chen (SC) multiphase/component model will be developed based on Lattice Boltzmann method (LBM) to describe the ultrasound-induced phase-transition motions between liquid perfluorocarbon (PFC) droplets and gaseous microbubbles, as well as relative impact factors such as ultrasound excitation parameters, droplet material properties and the surrounding fluid conditions. Then, by coupling micro-scale particle imaging velocity (PIV) apparatus with high-speed photography technology, an integrated experimental system will be set up to systemically investigate the ultrasound-induced liquid-to-gas phase-transition process and the complicated dynamic responses of vaporized microbubbles excited by ultrasound exposures. Finally, the theoretical model will be further improved by comparing the experimental observations with the simulated results, and an optimized ADV manipulation strategy will be developed by correlating the ultrasound excitation conditions with the phase-transition outcomes of ADV droplets and the dynamic responses of vaporized microbubbles. The results of current studies will provide solid theoretical and experimental bases for the comprehensive understanding of the fabrications and applications of ADVs in medical ultrasound areas, which plays an important role in the development and optimization of ultrasound diagnostic and therapeutic strategies in clinic.

液汽相变型乳化剂能够自由穿过血管内皮间隙到达肿瘤细胞，在超声激励作用下产生声致相变，由纳米液滴转变为微气泡，从而可用于超声造影、药物传递或超声治疗，在“一体化诊疗”方面有重要的应用前景。本项目拟开展声致液汽相变动力学的理论及实验研究。理论上建立一种基于多相流格子玻尔兹曼(LBM)方法的Shan-Chen伪势模型，以描述氟碳相变型纳米乳剂通过声致液汽相变形成微气泡的动态过程，并探讨超声激励条件、乳化剂材料性质及周围流体环境等对声致液汽相变的影响；实验上制备氟碳相变型纳米乳剂，研究将微尺度粒子速度成像PIV系统与高速摄影技术进行结合，基于实验测量结果验证并完善上述理论模型，确定超声激励条件及纳米乳剂制备工艺与相变过程的定量联系，最终建立实现稳定、可控的声致液汽相变现象的完整方案；结合上述研究结果探讨声致液汽相变在超声造影成像及药物输运等领域的应用，为指导临床治疗新方案奠定理论和实验基础。

液汽相变型乳化剂能够自由穿过血管内皮间隙到达肿瘤细胞，在超声激励作用下产生声致相变，由纳米液滴转变为微气泡，从而可用于超声造影、药物传递或超声治疗，在“一体化诊疗”方面有重要的应用前景。本项目拟开展声致液汽相变动力学的理论及实验研究。理论上建立一种基于多相流格子玻尔兹曼(LBM)方法的Shan-Chen伪势模型，以描述氟碳相变型纳米乳剂通过声致液汽相变形成微气泡的动态过程，并探讨超声激励条件、乳化剂材料性质及周围流体环境等对声致液汽相变的影响；实验上制备氟碳相变型纳米乳剂，研究将微尺度粒子速度成像PIV系统与高速摄影技术进行结合，基于实验测量结果验证并完善上述理论模型，确定超声激励条件及纳米乳剂制备工艺与相变过程的定量联系，最终建立实现稳定、可控的声致液汽相变现象的完整方案；结合上述研究结果探讨声致液汽相变在超声造影成像及药物输运等领域的应用，为指导临床治疗新方案奠定理论和实验基础。