Ultrastructure and Self-Cleaning Function of Moth (Notodontidae) and Butterfly (Lycaenidae) Wings

Abstract

Abstract. The microstructure, hydrophobicity, adhesion and chemical composition of the butterfly and moth wing surfaces were investigated by a scanning electron microscope (SEM), a contact angle meter, and a Fourier transform infrared spectrometer (FT-IR). Using ground calcium carbonate (heavy 3 CaCO ) as contaminating particle, the self-cleaning performance of the wing surface was evaluated. The wing surfaces, composed of naturally hydrophobic material (chitin, protein, fat, etc.), possess complicated hierarchical micro/nano structures. According to the large contact angle (CA, 148.3~156.2° for butterfly, 150.4~154.7° for moth) and small sliding angle (SA, 1~3° for butterfly, 1~4° for moth), the wing surface is of low adhesion and superhydrophobicity. The removal rate of contaminating particle from the wing surface is averagely 88.0% (butterfly wing) and 87.7% (moth wing). There is a good positive correlation ( 2 R =0.8385 for butterfly, 0.8155 for moth) between particle removal rate and roughness index of the wing surface. The coupling effect of material element and structural element contributes to the outstanding superhydrophobicity and self-cleaning performance of the wing surface. The wings of flying insect can be potentially used as templates for biomimetic preparation of biomedical interfacial material with multi-functions.