Automated, flexible and versatile manipulation of nanoliter-to-picoliter droplets based on sequential operation droplet array technique

Abstract

Droplet microfluidic technology has emerged as a powerful tool for biological analysis and screening. Currently, there is an urgent need to develop a versatile microfluidic droplet technique that can be adapted to different applications and widely adopted in routine laboratories. In this review, we introduce automated, flexible and versatile manipulation systems for nanoliter-to-picoliter droplets based on the sequential operation droplet array (SODA) technique. These systems flexibly combine three elementary operations of aspirating, depositing and moving to achieve various complicated droplet handling operations including droplet generation, splitting, fusion, transferring, addressing, capture and sorting, and have further completed different types of chemical and biological reactions, cell manipulation, miniaturized biochemical analysis and screening, demonstrating their high flexibility, good versatility, diversified functions, and broad adaptability. An overview of the SODA technique is presented in the aspects of its origin, setup, operations and characteristics, as well as its diverse applications in high-throughput screening, single-molecule and single-cell analysis, microscale cell assays and micro-sample analysis with high-resolution analysis systems. The advantages, limitations and development prospects of this technique are also discussed.