Researchers unveil hydrogen powered robotic jellyfish

Constructed from a set of smart materials, which have the ability to change shape or size as a result of a stimulus and carbon nanotubes, Robojelly is designed to mimic the natural movements of a jellyfish when placed in a water tank and is powered by chemical reactions taking place on its surface. "To our knowledge, this is the first successful powering of an underwater robot using external hydrogen as a fuel source," said Virginia Tech researcher Yonas Tadesse. According to Tadesse, the jellyfish was an ideal candidate to base the vehicle on because of its simple swimming action and prominent mechanisms. 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 was replicated in the vehicle using commercially available shape memory alloys (SMA) – smart materials that 'remember' their original shape – wrapped in carbon nanotubes and coated with a platinum black powder. The robot is powered by heat-producing chemical reactions between the oxygen and hydrogen in water and the platinum on its surface. The heat given off by these reactions is transferred to the artificial muscles of the robot, causing them to transform into different shapes. According to Tadesse, this green, renewable element means Robojelly can regenerate fuel from its natural surroundings and therefore doesn't require an external power source or the constant replacement of batteries. At the moment, the hydrogen powered device has been functioning whilst being clamped down in a water tank. While the researchers admit that the robot still needs development to achieve full functionality and efficiency, they believe it has enormous potential. Tadesse concluded: "The current design allows the jellyfish to flex its eight bell segments, each operated by a fuel powered SMA module. This should be sufficient for the jellyfish to lift itself up if all the bell segments are actuated. "We are now researching new ways to deliver the fuel into each segment so that each one can be controlled individually. This should allow the robot to be controlled and moved in different directions."