Researchers have developed a nano-coating with a self-cleaning effect. This coating is used to brush the surface of the car, so that the driver does not have to wash the car every day. This coating will form during the drying and film formation process. Concavo-convex morphology. Construct a hydrophobic layer (to prevent leakage). In this way, dust particles can only "hang up" on the coating surface, and eventually be taken away by the wind and rain. Researchers said this design Self-purification principle from the surface of lotus leaves. It can be inferred that the surface of the lotus leaf should be. ['There are many tiny pores.', 'Smooth leaves make dust particles nowhere to stand.', 'There are many tiny hairs and waxy bumps.', 'Star-shaped hairs radiating to all sides.']