(416e) Holographic Detection of Particles and Cells in the Microfluidic Labyrinth Device

There is tremendous interest in developing label-free approaches for isolation of circulating tumor cells (CTCs) from the blood of cancer patients as a means for liquid biopsy for cancer management. Recently, a microfluidic device called Labyrinth has been developed (Lin et al., 2017) that combined long loops and sharp corners to perform size-based inertial separation of CTCs with high throughput, excellent yield and high purity making it one of the most attractive label-free platforms in the field. In this study, we focus on understanding the hydrodynamic principles underlying such exceptional performance. We use in-line Digital Holography Microscopy (DHM), a three-dimensional imaging technique to analyze focusing dynamics of particles and cells in the Labyrinth device. We demonstrate three-dimensional localization of focused particles and cells in the Labyrinth device and quantify the effect of fluid inertia on the focusing behavior of particles and cells. We also investigate the effect of sharp corners and their role in focusing smaller cells. Finally, we develop optical signatures for distinguishing cancer cells from blood cells enabling us to not only use the Labyrinth device for label-free CTC isolation but also for staining-free CTC enumeration.