Fabrication on low voltage driven electrowetting liquid lens by dip coating processes

•Multilayered films are prepared by dip coating for low voltage electrowetting.•By loading different applied voltages, contact angle can be changed from 155° to 67°.•Interface curvature is able to be adjusted by the applied voltage.•The electrowetting liquid lens has a focal length from − 2 mm to 10 mm.

A low voltage driven electrowetting on dielectric liquid focus lens was fabricated based on a tiny glass tube which had been coated with ITO (indium tin oxide)–Al2O3–TiO2–Teflon multilayered thin films on the inside. Method of sol–gel/chemical solution dip coating was used for the film preparation. A cambered interface between silicon oil and aqueous solution containing NaCl and sodium dodecyl sulfate (SDS) was used for the lens refraction. The curvature of the interface was adjusted by changing the applied voltage. The contact angle of aqueous solution in oil atmosphere was reduced from 155° to 67° when − 10 V DC was applied. The leakage current was only 28 nA at that applied voltage and its focal length changed from − 2 mm to infinity then to 10 mm.