Introduction
In nature, very thin and lightweight silkworm cocoons can protect silkworms from physical attacks from predators or the environment while supporting their metabolic activity. Evolved over thousands of years' natural selection, silkworm cocoons are hierarchical and multifunctional. Their biological functions such as defence against natural enemies, thermal regulation and anti-bacterial function are essential for the survival of silkworms residing inside. These functions are attracting increasing attention from researchers to understand the structure and property of this important biological material and to design and develop next-generation bio-mimic protective materials [1], [2], [3] and [4].