In the past 20 years,microfluidic technique has undergone fast progress,and various manipulation techniques for microfluids have been developed,including hydrodynamic,electrokinetic,microvalve/pump,centrifugation,and electrowetting techniques.Despite the successful and broad applications of these techniques,automated and flexible liquid handling techniques with high versatility are still in urgent need.Recently,on the basis of the DropLab system [1],we developed a sequential operation droplet array(SODA)system for performing fully-automated picoliter to nanoliter-scale droplet manipulation,analysis and screening [2].The SODA system has a simple setup consisting of a tapered capillary-syringe pump module and a twodimensional oil-covered droplet array fixed on a x-y-z translational stage [2].An automated liquid handling strategy was developed with the SODA system using the programmable combination of the capillary-based liquid aspirating-depositing and the moving of the oil-covered droplet array,so-called “aspirating-depositing-moving”(ADM)mode.Complex and flexible liquid handling manipulations can be achieved with picoliter-scale precision,including liquid droplet assembling,generation,indexing,transferring,splitting and fusion.We applied the SODA system in screening of inhibitors for capases-1 from a chemical library.The consumptions of samples and reagents are only 60–180 pL for each droplet microreactor,which are commonly 3–5 orders of magnitude lower than those of conventional multi-well plate systems.We also applied the SODA system in cell-based schedule dependent drug combination screening with multi-step operations involving cell culture,medium changing,drug dosage and stimulation,and cell viability testing [3].Most recently,we applied the SODA system in large-scale screening of crystallization conditions of five soluble proteins and one membrane protein with 35–96 different crystallization conditions and droplet reactor volumes of 4–8 nL [4].The protein consumption significantly reduces 50–500 fold compared with current crystallization stations.The SODA systems use the different combination of simple unit operations(ADM)to automatically achieve complex droplet manipulations,which have provided a versatile and flexible platform for picoliter-scale liquid handling,analysis,and screening for multiple different samples.The SODA strategy may also provide a novel liquid manipulation technique for microfluidic systems,besides the previously-reported techniques.