A review on microdroplet generation in microfluidics

Micro-nanofluidic technology is widely used in food safety testing, drug screening, new material synthesis and bioengineering. Droplet microfluidic technology is an important branch of micro-nanofluidic technology. The microdroplet technology can produce high-throughput monodisperse droplets. The droplet technology overcomes many problems of continuous flow, such as small sample reagent volume, no cross-contamination, and rapid chemical reaction. So microdroplets have an important position in the fields of single cell analysis, gene sequencing, and real-time diagnosis. This review focuses on the different methods and applications of microdroplet generation in microfluidics. The droplet generation methods are passive and active methods. The passive method does not require external force, while the active method requires external force such as external electric field, magnetic field, acoustic field, and laser field. It is predicted that the quantitative generation of droplets on demand in microfluidics will be the important direction for future research. This review provides new ideas for the applications of the quantitative generation of microdroplets on demand in microfluidics.