High-speed, clinical-scale microfluidic generation of stable phase-change droplets for gas embolotherapy.
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.
Department of Biomedical Engineering, University of California, Irvine, CA 92697, USA.
David
D
Bardin
Thomas D
TD
Martz
Paul S
PS
Sheeran
Roger
R
Shih
Paul A
PA
Dayton
Abraham P
AP
Lee
D004129:Dimethylpolysiloxanes / Q000737:chemistry; D005466:Fluorocarbons / Q000737:chemistry*; D046210:Microfluidic Analytical Techniques / Q000295:instrumentation / Q000379:methods*; D010316:Particle Size; D044367:Phase Transition; D013696:Temperature; D010420:Pentanes
D004129:Dimethylpolysiloxanes; D005466:Fluorocarbons; C013830:baysilon; C008806:perfluoropentane; D010420:Pentanes