Department of Biomedical Engineering, University of California, Irvine, CA 92697, USA.
Lab Chip. 2011 Dec 7;11(23):3990-8. doi: 10.1039/c1lc20615j. Epub 2011 Oct 20.
In this study we report on a microfluidic device and droplet formation regime capable of generating clinical-scale quantities of droplet emulsions suitable in size and functionality for in vivo therapeutics. By increasing the capillary number-based on the flow rate of the continuous outer phase-in our flow-focusing device, we examine three modes of droplet breakup: geometry-controlled, dripping, and jetting. Operation of our device in the dripping regime results in the generation of highly monodisperse liquid perfluoropentane droplets in the appropriate 3-6 μm range at rates exceeding 10(5) droplets per second. Based on experimental results relating droplet diameter and the ratio of the continuous and dispersed phase flow rates, we derive a power series equation, valid in the dripping regime, to predict droplet size, D(d) approximately equal 27(Q(C)/Q(D))(-5/12). The volatile droplets in this study are stable for weeks at room temperature yet undergo rapid liquid-to-gas phase transition, and volume expansion, above a uniform thermal activation threshold. The opportunity exists to potentiate locoregional cancer therapies such as thermal ablation and percutaneous ethanol injection using thermal or acoustic vaporization of these monodisperse phase-change droplets to intentionally occlude the vessels of a cancer.
在这项研究中，我们报告了一种微流控装置和液滴形成模式，能够生成适合体内治疗的临床规模数量的液滴乳液，其大小和功能合适。通过提高基于连续相流速的毛细管数——在我们的流聚焦装置中，我们检查了三种液滴破裂模式：几何控制、滴落和射流。在我们的装置以滴落模式运行的情况下，会以超过每秒 10^5 个的速率生成高度单分散的液态全氟戊烷液滴，其直径在适当的 3-6 μm 范围内。基于与液滴直径和连续相与分散相流速比相关的实验结果，我们推导出一个幂级数方程，该方程在滴落模式下有效，用于预测液滴尺寸，D(d)约等于 27(Q(C)/Q(D))(-5/12)。本研究中的挥发性液滴在室温下稳定数周，但在超过均匀热激活阈值时会迅速发生液-气相转变和体积膨胀。存在利用这些单分散相变液滴的热或声蒸发来增强局部癌症治疗（如热消融和经皮乙醇注射）的机会，以有意阻塞癌症的血管。
