Evaluation and comparison of two microfluidic size separation strategies for vesicle suspensions

Two size-based separation strategies are evaluated for suspensions consisting of giant unilamellar vesicles with a broad, continuous distribution of diameters. Microfluidic devices were designed to separate an initial suspension into larger and smaller particles via either filtration or inertial focusing. These separation mechanisms were tested with suspensions of vesicles and suspensions of rigid spheres separately to illustrate the effect of deformability on separation ability. We define several separation metrics to assess the separation ability and to enable comparison between separation strategies. The filtration device significantly reduced the polydispersity of the separated vesicle fractions relative to the starting suspension and displayed an ability to separate vesicle suspensions at high throughputs. The device that utilized inertial focusing exhibited adequate polydispersity reduction and performed best with diluted vesicle suspensions. The inertial device had fewer issues with debris and trapped air, leading to short device preparation times and indicating a potential for continuous separation operation.