Diamagnetic Manipulation of Cell-Encapsulating Droplets

In this thesis, a microfluidic method for label-free control of cell encapsulating droplets is developed using diamagnetic forces. To generate droplets in a microfluidic device, we use a symmetrical flow-focusing design, where two streams of a continuous phase shear a single stream of a droplet phase, resulting in droplet generation. First, it is shown that by adjusting only the droplet phase flow rate, precise control of empty droplets can be achieved. Human prostate cells are then introduced to the system and encapsulated by droplets. Control of the cell-encapsulated droplets and empty droplets is studied. It is shown that cell-encapsulated droplets and empty droplets deflect by different amounts when exposed to the magnetic field. By exploiting this difference, efficient sorting of empty droplets from cell-encapsulated droplets is achieved at a purity of 85% in a single pass. Following sorting, cells are analyzed and show 90% viability after a two-hour incubation period.