(a) Chemical structures of yellow dye A3MA and red dye DR1A. (b) Schematic illustration of the molecular alignment of the splayed structure through the thickness of the film. (c) Schematic representation of the photo-driven asymmetric motion produced by artificial cilia. (d) Front view of multicolour cilia motion in water irradiated with visible (4 mW/cm²) and UV (9 mW/cm²) light. Scale bar: 0.5 mm. Reprinted with permission from Ref. [69].