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This New Invisible Gel Robot Is a Stealthy Underwater Predator

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As if the ocean wasn’t already full of nightmares, researchers at MIT have developed a soft and flexible robot made of hydrogel, a material composed mostly of water. The new bot is quick, strong, and almost completely invisible when submerged, allowing it to snatch up fish before they even realize they’re being tracked.

On land, the hydrogel robot would be as intimidating as a bowl full of Jello, but when it’s under water, its neutral buoyancy allows it to move around without the need for complex hydraulics or electric motors. Made up of what appear to be a series of hollow, connected rubbery cubes, these bizarre robots are brought to life by simply pumping water in or out of their inner chambers, which causes them to curl up or unfurl.

The movements are undoubtedly basic, but they’re still enough to allow the robot to sneak up and snatch a fish like a real sea predator. At a core level, the muscles in your body don’t do much more than expand and contract, so these prototype hydrogel robots might just be the start of more complex creations.


In fact, in a paper detailing the research, the researchers discuss the potential applications for their creatures:

Bioactive components (for example, drugs, bacteria and mammalian cells) can be further incorporated in the hydrogel devices for sustained release and controlled delivery. Marine biologists can use hydrogels to design next-generation biomimetic robots more realistic than elastomeric and metallic ones to study their interactions with sea animals.


Because the hydrogel material is made mostly of water, it’s nearly invisible when submerged. The MIT researchers envision their creations as underwater spies that marine biologists could use to study sea life in its natural environment, without disturbing the activities of the creatures they’re observing.

Outside a marine environment, the BBC recently did something similar with a series of camera-equipped robot animals designed to capture the activities of monkey, orangutans, and even otters in the wild. While the footage the bots were able to capture was remarkable, it was hardly natural—the curious animals cautiously interacted with the artificial intruders. With any luck, these hydrogel robots could have more luck. Watch out, creatures of the sea—the robot takeover is coming for you, too.

[YouTube, Nature]