Droplet preparation and size control device based on electrowetting step emulsification

A droplet preparation and size control device based on electrowetting step emulsification, comprising:

• a syringe pump (1), a metal pipeline (3), a micro-channel (4), two electrode plates (5), a continuous phase container (6) and a direct-current power supply (7), wherein:
• the syringe pump (1), the metal pipeline (3) and the micro-channel (4) are successively connected;
• an outlet of the micro-channel (4) is clamped and sealed between the two electrode plates (5);
• each electrode plate (5) consists of four layers, respectively a base layer, a conducting layer, an insulating layer and a hydrophobic layer;
• a cathode of the direct-current power supply (7) is connected with the metal pipeline (3), and an anode of the direct-current power supply (7) is connected with the conducting layer of each electrode plate (5);
• the syringe pump (1) is filled with dispersed phase fluid;
• continuous phase fluid is injected into the continuous phase container (6) and immerses the electrode plates (5);
• the syringe pump (1) is pulled, so that droplets are generated at lower parts of the electrode plates (5);
• then the direct-current power supply (7) is switched on, so as to enable the dispersed phase fluid in the micro-channel (4) to be negatively charged;
• the two electrode plates (5) are positively charged and form a capacitor;
• when a flow of the syringe pump (1) changes, sizes of the droplets are adjusted through adjusting a voltage of the direct-current power supply (7), so as to stably obtain the droplets with a specified diameter;
• the dispersed phase fluid is a conducting solution, and the continuous phase fluid comprises components of silicone oil and surfactant.