Programmable Stretchable Surfaces Inspired by Octopuses

Innovation: Academia

Cornell University

2017

Image: Isabel Galvez / Unsplash / Free non-commercial use

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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Optimize Shape/Materials

Resources are limited and the simple act of retaining them requires resources, especially energy. Living systems must constantly balance the value of resources obtained with the costs of resources expended; failure to do so can result in death or prevent reproduction. Living systems therefore optimize, rather than maximize, resource use. Optimizing shape ultimately optimizes materials and energy. An example of such optimization can be seen in the dolphin’s body shape. It’s streamlined to reduce drag in the water due to an optimal ratio of length to diameter, as well as features on its surface that lie flat, reducing turbulence.

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Patents

US20190126516A1
4.0 MB PDF

Stretchable surfaces from Cornell are made of extensible silicone with inextensible mesh that can instantly transform from a flat sheet to a 3D shape.

Benefits

Flexible
Reversible
Shape-shifting

Applications

Robotics
Medical implants

UN Sustainable Development Goals Addressed

Goal 9: Industry Innovation & Infrastructure

The Challenge

Inflatable objects like balloons typically form unchangeable shapes. For example, taking a round balloon and reshaping it into a box is nearly impossible. This inability to change shapes results from a lack of order and control within the elastic base material.

Innovation Details

The stretchable surface is called a “Circumferentially Constrained and Radially Stretched Elastomer,” abbreviated as CCOARSE. It is made of a laser-cut rigid mesh attached to a stretchable silicone elastomer. The rigid mesh constrains the overall material to a targeted shape when the whole material is inflated.

Biomimicry Story

Some animals such as cephalopods use soft tissue to change shape reversibly, helping them hide or manipulate objects. Cephalopods have conical papilla with strong erector muscles. These muscles create forces that pressurize and stretch the animal’s tissue in different directions, enabling them to embody a variety of shapes.

See Related Content

Biological Strategy

Arterial Walls Resist Stretch Disproportionately

Cephalopods

The arterial walls of many animals resist stretch disproportionately by incorporating non-stretchy collagen fibers in a particular arrangement.

References

Journal article

Stretchable surfaces with programmable 3D texture morphing for synthetic camouflaging skins

Science

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