Shape Memory Alloys

The Robojelly mentioned in above note used Shape Memory Alloys. The live jellyfish is an ideal invertebrate to base the vehicle on due to its simple swimming action: it has two prominent mechanisms known as “rowing” and “jetting”. A jellyfish’s movement is down to circular muscles located on the inside of the bell – the main part of the body shaped like the top of an umbrella. As the muscles contract, the bell closes in on itself and ejects water to propel the jellyfish forward. After contracting, the bell relaxes and regains its original shape.

This has been replicated in the Robojelly, using commercially available Shape Memory Alloys (SMA) wrapped in carbon nanotubes and coated with a platinum black powder.

Shape Memory Alloys are smart materials that “remember” their original shape. The two main types of shape-memory alloys are the copper-aluminium-nickel, and nickel-titanium and (NiTi) alloys but SMAs can also be created by alloying zinc, copper, gold and iron.