Unique morphology and mechanical property of Chinese sturgeon (Acipenser sinensis) fish skin.

Chinese sturgeon (Acipenser sinensis) fish skin is an excellent natural material with remarkable mechanical properties owing to the unique structures of the helical stacking fibres. In this work, the authors studied the potential role of the sturgeon fish skin in the protective function through testing and analysed the structural features and mechanical properties of the stratum compactum in the fish skin. Scanning electron microscopy images of the sturgeon fish skin revealed that the skin was primarily composed of the stratum compactum. The stratum compactum was characterised by the helically arranged fibre structures and the helical-ply angle decreased from the anterior region of the fish body to the posterior region. Mechanical tests containing tension and penetration experiments demonstrated that the stratum compactum provided the sturgeon fish skin the capability to effectively resist bite and laceration by predators. Furthermore, the experimental results also confirmed that the sturgeon fish skin showed two distinct mechanisms against tension and penetration. These findings may provide a novel biomimetic design template for both flexible and tough body armour.