High-speed, clinical-scale microfluidic generation of stable phase-change droplets for gas embolotherapy

Lab on a Chip Pub Date: 2011-10-20 DOI: 10.1039/C1LC20615J

Abstract

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 105 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, Dd ? 27(QC/QD)?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.

Graphical abstract: High-speed, clinical-scale microfluidic generation of stable phase-change droplets for gas embolotherapy
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