A droplet-based microfluidic system capable of droplet formation and manipulation

Formation of emulsion droplets is crucial for a variety of industrial and scientific applications. This study presents a new droplet-based microfluidic system capable of generating tunable and uniform-sized droplets and subsequently deflecting these droplets at various inclination angles using a combination of flow-focusing and moving-wall structures. A pneumatic air chamber was used to activate the moving-wall structures, located nearby the outlet of the flow-focusing microchannels, such that the sheath flows can be locally accelerated. With this approach, the size of the droplets can be fine-tuned and sorted without adjusting the syringe pumps. Experimental data showed that droplets with diameters ranging from 31.4 to 146.2 μm with a variation of less than 5.39% can be generated. Besides, droplets can be sorted upwards or backwards with an inclination angle ranging from 0° to 53.5°. The development of this emulsion system may be promising for the formation and collection of emulsion products for applications in the pharmaceutical, cosmetics and food industries.