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Self-Charging Robo-Jellyfish Are Here, and the Navy Wants Them

The weird, gooey robot war is getting heated quick: Earlier this week we heard about the "strange blob-bot":, an amoeba-mimicking, pulsating little horror of a robot...
March 21, 2012, 2:00pm

The weird, gooey robot war is getting heated quick: Earlier this week we heard about the strange blob-bot, an amoeba-mimicking, pulsating little horror of a robot. But that’s nothing in the face of news that engineers at Virginia Tech have built a robotic jellyfish.

As if the threat of the oceans being taken over by deadly stinging jelly cyborgs isn’t scary enough, there’s this: The researchers claim that, because their Robojelly is powered by a hydrogen-based catalytic reaction, rather than electricity, it could “theoretically” power itself indefinitely. When you consider our best options for powering underwater craft are currently batteries, nuclear reactors, or tethers to the surface, a chemically-powered propulsion system is groundbreaking (and, well, a bit nerve-wracking).


Okay, let’s just step back from the terror for a moment to watch that video. The Robojelly is beautiful. There’s something hauntingly gorgeous about the slow, rhythmic fluttering of live jellyfish — which, really, are so fascinating because it doesn’t seem like they could be alive in the first place. Now, after being accustomed to awkward robotic mimicry like tumbling Asimo, to see the slow flapping of the Robojelly’s bioreplicant bell is hypnotizing. Perhaps the robots aren’t all bad after all?

Robojelly isn’t only pretty, it’s a marvel of materials engineering. According to a paper published today in Smart Materials and Structures, Robojelly’s bell is constructed from nano-platinum catalyst-coated multi-wall carbon nanotube sheets, which are wrapped around a nickel-titanium shape memory alloy. When the platinum catalyst layer makes contact with a mixture of oxygen and hydrogen gases, heat is released, which causes the memory alloy to change shape, powering the jelly’s movement. In simpler terms, the robot’s sandwich construction allows it to be chemically powered, rather than powered by electricity.

“To our knowledge, this is the first successful powering of an underwater robot using external hydrogen as a fuel source,” lead author Yonas Tadesse said.

What’s truly mindblowing is just how similar the Robojelly’s locomotion process is to natural jellyfish. The biomechanics of natural jellies are ripe for replication because of their simple movements of expanding and contracting their bells to propel water. Currently, Robojelly is only designed to activate all of its bell segments at once. But the goal is to get each lobe of the bell working independently so the Robojelly can, you know, steer.


“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,” Tadesse said. “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.”

Disappointingly, the authors mention that the Robojelly in the above video is still electrically powered, as the chemical system needs refinement for full power. (A hydrogen-powered version works underwater, but has to be held with a clamp as it isn’t producing enough power to keep itself from sinking.) But nonetheless, the potential of the platform is incredible.

That potential would be why the Office of Naval Research provided funding for the work. As humorous as it is to think about deadly robo-jellyfish, the Navy has made it clear that it wants drone subs flooding the world’s oceans with near-indefinite ranges. A self-sustaining catalytic propulsion system, albeit not particularly high-performance, would certainly do the trick. Imagine the day that the Navy is releasing thousands of Robojelly drones to monitor sensitive waters, like the Strait of Hormuz. Sure, it sounds silly and far-fetched, but it’s not. Just pray they don’t add tentacles.

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