Nature-inspired materials could help camouflage

Researchers mimic humpback whales' flippers
to build turbine blades 

Smart clothes that change colour could help people to camouflage - just like squid and zebrafish do, say scientists.

A team at the University of Bristol has developed artificial muscles that mimic the colour-changing ability of squid.

The technology falls into the category of soft robotics - a domain that blends together organic chemistry, soft materials science, and robotics.

The study appears in the journal Bioinspiration and Biomimetics.

Soft robots
The University of Bristol team decided to combine biomimicry - technology that imitates nature - and robotics.

"We study and mimic the characteristics of biological organisms to create soft robots and soft devices," says Dr Rossiter.


"Where conventional robots are rigid and inflexible, we focus instead on the soft structures that nature is so good at making.

"These include artificial muscles."

To create the artificial muscles, the researchers studied how certain animals changed colour.

They do it for various reasons - in case of danger, or depending their mood, stress level, changes in outside temperature, when communicating or attracting a mate.

Cephalopods - squid, cuttlefish and octopuses - change colour by using tiny muscles in their skins to stretch out small sacs of black colouration.

These sacs are located in the animal's skin cells, and when a cell is ready to change colour, the brain sends a signal to the muscles and they contract.

This makes the sacs expand and creates the optical effect which makes the animal look like it is changing colour.



The scientists also noted that zebrafish had a different camouflaging ability - by pumping black pigmented fluid from under the skin to the surface of the skin.

Smart materials
To mimic these natural mechanisms, the team used "smart" electro-active polymeric materials, connected to an electric circuit.

When a voltage was applied, the materials contracted; they returned to their original shape when they were short-circuited.