Figure 3.

(a) Schematics of the microfluidic device used for preparing initial single emulsion droplet and the droplet changed from one layer to two and three layers. (b) Formation of single, double, and triple emulsion droplets over time due to phase separation. The scale bar is 100 µm. The hydrophobic fluorescent indicator Nile red was premixed into the inner phase mixture and automatically assembled into the PEGDA 250-rich layer during the phase separation process. The PEGDA 250-rich layer was labeled with a bright yellow fluorescent region.