Self-powered robot mimics jellyfish

BLACKSBURG, Va., March 22 (UPI) -- U.S. researchers say their robotic jellyfish, named Robojelly, could -- theoretically at least -- never run out of energy because it's fueled by hydrogen.

Scientists at Virginia Tech say Robojelly can mimic the natural movements of a jellyfish when placed in water, 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," lead study author Yonas Tadesse said.

Robojelly, constructed from smart materials that have the ability to change shape or size in response to a stimulus, exhibits characteristics ideal for use in underwater search and rescue operations, a release from the Institute of Physics reported Wednesday.

A jellyfish moves by contracting circular muscles located on the inside of the bell -- the main part of its body, shaped like the top of an umbrella -- closing the bell in on itself and ejecting water to propel itself.

Robojelly is made of shape memory alloys -- smart materials that "remember" their original shape -- and powered by heat-producing chemical reactions between the oxygen and hydrogen in water and platinum that coats the robot's surface.

The heat of reactions is transferred to the artificial muscles of the robot, causing them to transform into different shapes, mimicking the jellyfish's method of movement.