Abstract: Many biological surface are hydrophobic because of their complicated composition and surface microstructure. Eleven species (four families) of butterflies were selected to study their micro-, nano-structure and super-hydrophobic characteristic by means of Confocal Light Microscopy, Scanning Electron Microscopy and Contact Angle Measurement. The contact an-gles of water droplets on the butterfly wing surface were consistently measured to be about 150˚ and 100˚ with and without the squamas, respectively. The dust on the surface can be easily cleaned by moving spherical droplets when the inclining angle is larger than 3˚. It can be concluded that the butterfly wing surface possess a super-hydrophobic, water-repellent, self-cleaning, or "Lotus-effect" characteristic. The contact angle measurement of water droplets on the wing surface with and without the squamas showed that the water-repellent characteristic is a consequence of the microstructure of the squamas. Each water droplet (diameter 2 mm) can cover about 700 squamas with a size of 40 μm×80 μm of each squama. The regular riblets with a width of 1000 nm to 1500 nm are clearly observed on each single squama. Such nanostructure should play a very important role in their super-hydrophobic and self-cleaning characteristic.

Key words: biomimetics, bionics, butterfly, super-hydrophobic, nanostructure, self-cleaning