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Watch MIT's swimming hydrogel robot sneak up and grab a passing fish

“Just when you thought it was safe to go back in the water!”

That may be the tagline to 1978’s Jaws 2, but it also nicely sums up the work of researchers at Massachusetts Institute of Technology, who have developed new gel-based underwater robots capable of a range of terrifyingly high-energy tasks — including swimming like an eel, and snatching (and then releasing) a live fish as it swims along minding its own business.

“In this work, we present the world’s first report of a fully hydrogel-made hydraulic actuator with fast and forceful actuation,” MIT graduate student Hyunwoo Yuk, who worked on the project, told Digital Trends. “It is operated by pumping in and out water. There are two significant progress in this work. [The first is that] it enables fast and forceful actuation, similar to fishes, for a fully hydrogel-based system which have been not possible [before]. [Secondly], due to its high water contents, hydrogel robots are optically and sonically transparent in water like a glass eel in the ocean.”

A transparent, eel-like soft robot might sound like the stuff nightmares are made of, but it’s nonetheless an impressive achievement. The robots built by the MIT team are made up of interlocking hydrogel cubes, capable of inflating when they’re pumped up with water.

By doing this rapidly the robots are able to produce forceful reactions, generating a few newtons of force in just one second. By comparison, other hydrogel robots which use osmosis to achieve similar goals take several minutes, or even hours, to achieve marginal millinewton forces.

At present, the team is still experimenting with form factors — including the aforementioned eel and a soft, hand-shaped robot that is able to both squeeze and relax. The work does have some excitingly broad practical applications, however.

“The hydrogel actuators and robots may be used to interact with soft and delicate tissues and organs in human body,” Yuk continued. “For example, [they could] assist [a] heart beating by applying pressuring through hydrogel. Since hydrogels are soft, wet and biocompatible, they can fit inside the human body well. Also, its optical and sonical transparency will enable new types of underwater surveillance robots or other applications that require such passive camouflage.”

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