Shape-Memorizing Textile Inspired by the Angora Rabbit

Innovation: Academia

Harvard

2020

Image: Vickie Maris / Flickr / CC BY - Creative Commons Attribution alone

Physically Assemble Structure

Living systems use physical materials to create structures to serve as protection, insulation, and other purposes. These structures can be internal (within or attached to the system itself), such as cell membranes, shells, and fur. They can also be external (detached), such as nests, burrows, cocoons, or webs. Because physical materials are limited and the energy required to gather and create new structures is costly, living systems must use both conservatively. Therefore, they optimize the structures’ size, weight, and density. For example, weaver birds use two types of vegetation to create their nests: strong, a few stiff fibers and numerous thin fibers. Combined, they make a strong, yet flexible, nest. An example of an internal structure is a bird’s bone. The bone is comprised of a mineral matrix assembled to create strong cross-supports and a tubular outer surface filled with air to minimize weight.

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Modify Size/Shape/Mass/Volume

Many living systems alter their physical properties, such as size, shape, mass, or volume. These modifications occur in response to the living system’s needs and/or changing environmental conditions. For example, they may do this to move more efficiently, escape predators, recover from damage, or for many other reasons. These modifications require appropriate response rates and levels. Modifying any of these properties requires materials to enable such changes, cues to make the changes, and mechanisms to control them. An example is the porcupine fish, which protects itself from predators by taking sips of water or air to inflate its body and to erect spines embedded in its skin.

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Biocompatible textile from Harvard University uses keratin to create strong shape-memory fibers.

Benefits

Reduced waste
Customizable
Reversible

Applications

Smart textiles
Medical devices

UN Sustainable Development Goals Addressed

Goal 12: Responsible Production & Consumption

Bioutilization

Keratin
Angora rabbit

The Challenge

Textile production often emits large amounts of greenhouse gases, which are harmful to people and the planet. Additionally, typical textiles are made of petroleum-based materials that take hundreds of years to degrade. When these materials are discarded, the entire item or part of it could end up as pollution.

Innovation Details

The textile is made from keratin, a fibrous extracted from leftover Angora wool waste from the textile industry. The keratin is 3D printed into specific shapes, and is able to revert back to that shape after deformation.

Biological Model

The Angora rabbit has a layer of dense hair on its body. This hair contains a protein called keratin, which has shape memory due to its spring-like structure. When two of these chains twist together, it forms a structure known as a coiled coil. When several coiled coils are joined together, they form the fibers that create hair.

References

Journal article

A bioinspired and hierarchically structured shape-memory material

Nature Materials

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