Fig. 1. Schematic diagram of electrowetting principle，Where γ represents interfacial tension．

Fig. 2. Principle of electrowetting display

Fig. 3. Structure formula of electrowetting display dyes

Fig. 4. Structure formula (a) and electrowetting curves (b) of four ionic liquids with different negative ions^［33］

Fig. 5. Schematic diagram of ion diffusion mechanism under positive and negative bias^［34］

Fig. 6. Molecular structures of fluororesin Teflon^®AF series，Cytop^® series and Hyflon^® AD series.

Fig. 7. Leakage current and breakdown of fluororesin layer during the failure process of electrowetting device under 0~135 V^［36］

Fig. 8. (a) Leakage current curves of Teflon^®AFX/Parylene double-layer insulation structure in 96 h reliability test； (b) Leakage current curves of 96 h reliability test for single layer Teflon^®AFX insulation structure^［40］．

Fig. 9. (a) SEM image of pixel wall structure in EWD device； (b) SEM image of pixel wall cross section.

Fig. 10. (a) Chemical structure formula of SU-8 photoresist resin ^［45］； (b) Molecular structure diagram of Surflon material^［46］．

Fig. 11. (a) Schematic diagram of UV induced surface polymerization grafting reaction of SU-8 photoresist； (b) Reaction equation^［49］； (c) Flow chart of surface ring opening polymerization grafting reaction of SU-8 photoresist^［50］．

Fig. 12. Molecular structure formula of inorganic (a）/organic (b) siloxane，R is organic chain^［54］.

Fig. 13. Molecular structure formula of organosiloxane (a) and photo reaction equation during exposure (b）. X is photo crosslinkable group，Y is organic group，Z is hydrogen atom or organic group^［53］.

Fig. 14. Structure diagram of electrowetting display

Fig. 15. Flow chart of electrowetting display production^［56］

Fig. 16. Process flow of preparing fluororesin layer by ink jet printing

Fig. 17. Patterned pixel wall after negative photoresist coating (a），exposure (b），and development (c），optical micrographs(d）^［59］ and SEM image(e）^［62］ of the pixel wall structure.

Fig. 18. Technological process of nano-imprinting technology，(b），(c) and (d) are SEM photos of hard template，soft template and target pattern^［63］，respectively.

Fig. 19. Schematic diagram of liquid separation and filling equipment.Yellow is pixel wall； Red is ink； White is bubble zone.

Fig. 20. Comparison of vertical immersion filling method in university of Cincinnati (a) and Liquivista self-assembly filling method (b）

Fig. 21. Flow chart of preparation of phase change filling ink and electrowetting display device

Fig. 22. Flow chart of ink-jet printing filling ink and electrowetting display device preparation

Fig. 23. Full color electrowetting display structure based on color filter

Fig. 24. Color electrowetting display structure based on single layer three primary color ink filling

Fig. 25. Schematic diagram of red display effect

Fig. 26. (a) Schematic diagram of three-layer superimposed color electrowetting display； (b) Color mixing method.