Natural Lightweight Material Exhibits Strength, Toughness

Replica of an insect wing made from shrilk (Wyss Institute, Harvard University)

Researchers at Harvard University have developed a new biodegradable material with the strength and toughness of an aluminum alloy, but only half the weight. Postdoctoral bioengineering fellow, Javier Fernandez and professor Donald Ingber in Harvard’s Wyss Institute for Biologically Inspired Engineering describe their discovery in the advance online issue of the journal Advanced Materials (paid subscription required).

The new material called “Shrilk” is made from the fibroin protein in silk and chitin, which is taken from discarded shrimp shells. The biodegradable substance resembles the properties of insect cuticle, the material found in the rigid exoskeleton of a housefly or grasshopper that provides the structure for the insects’ muscles and wings.

Fernandez and Ingber modeled Shrilk on the chemistry and structure of insect cuticle, with laminated layers of a polysaccharide polymer and protein. As a result, they engineered a thin, clear film that has the same composition and structure as insect cuticle.

The authors say Shrilk is similar in strength and toughness to an aluminum alloy, but has only half the weight. It is biodegradable and can be produced at a low cost, since chitin is readily available as a shrimp waste product. Shrilk can be molded into complex shapes, such as tubes, and produce the wide variations in stiffness, from elasticity to rigidity, by adjusting the water content.

Shrilk has a number of potential industrial and commercial applications. Its biodegradable properties can make it an environmentally acceptable alternative for packaging, trash bags, and diapers. Shrilk is also biocompatible, making it potentially suitable for medical applications such as weight-bearing sutures or scaffolding for tissue regeneration.

Read more: Industry, Academic Team Creates Ultralight Material

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