High-throughput generation of uniform droplets from parallel microchannel droplet generators and the preparation of polystyrene microsphere material

To prepare uniform polystyrene particles with ten microns of diameter,a parallel scaling-up strategy for the capillary-assembled stepwise microchannel was developed,which created uniform droplets with high-throughput and formed a large amount of emulsion templates for the polymerization of styrene and cross-linker.The microchannel droplet generator was robust for the flow rate deviation of the continuous phase in the jetting flow,and droplet generation frequency up to 2.8 x 104 Hz was achieved with only four parallel droplet generators,which were much more efficient than the parallelly scaled microfluidic devices working in dripping flow.32-52μm average diameter droplets with 4.5%-8.4%diameter variation coefficients were successfully prepared from the microchannel device fabricated by low-cost 3D-print method,and the droplets were subsequently turned to solid particles via a two-step polymerization in the platform.The polystyrene particles were further reduced to 16.9-23.5μm with 5.0%-8.6%diameter variation coefficients due to the accompanying emulsion polymerization,and the working capacity of the platform reached hundred milligrams of particles per hour.