Single-cell analysis allows us to analyze in depth the differences and changes of the cell. How to generate a single-cell, we present two ways of Droplet-based microfluidic technology that enables high-throughput screening of single cells and Hydrodynamics focusing on the fluid compression allows the cells are arranged in a single row. Viscosity of liquid each kind of affecting the speed in the flow, which we quantify the threshold velocities in terms of the Capillary number, Ca, showing that Ca can be used to reliably predict thresholds for combinations of fluids that have matched viscosities. Ca=Uη/γ . This technology is particularly suitable for working with cells of limited availability, such as stem cells or primary cells from patients