This Robotic Fish Is Destined for Underwater Exploration — and Maybe Your Arteries

A new soft robot design is durable and transparent, and someday might even be radically miniaturized to swim in the bloodstream.

If you woke up today wondering what's new in the world of transparent robot fish, well, we have a most coincidental piece of news to report. 

Scientists in China recently unveiled a new kind of soft-bodied aquatic robot that can swim more than twice as fast as previous robots with similar designs. The bot could be used in the near future to safely explore coral reefs and shipwrecks, designers say. Or, further down the line, it could be radically miniaturized and used in medical applications, actually swimming around inside the human body. 

The biomimetic fishbot, which actually looks more like a manta ray, has a few other things going for it. Most of its parts are transparent, making it close to invisible in the water. The device can handle temperatures from freezing to boiling, which is useful for ocean exploration scenarios. And its high-voltage power system won't harm any adjacent fish or divers. Not yet, anyway. Presumably, the robots will learn to weaponize themselves after the robot revolution, but hey — that's a problem for another day. 

In the meantime, this new Chinese model solves several major soft-robot design dilemmas that have been frustrating engineers for a while. Most significantly, it doesn't have a motor in any traditional sense, using electrically actuated soft materials for locomotion instead. When the onboard battery delivers an electric pulse, ionically conducive hydrogels trigger the bot's fins to flap and twitch in specific patterns. This propels it forward at an average of 2.5 inches per second, which is 0.69 times its body length. 

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The current prototype versions of the fishbot, outlined in an article in the journal Science Advances, can operate up to three hours without a recharge, and down the line could be outfitted with cameras and sensors. Demonstration footage of the untethered unit (dyed green) is pretty underwhelming when you consider that the new design is twice as speedy as its competition. But tethered, the device moves at an impressive max of more than five inches per second.

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Emailing from China, researcher Tiefeng Li explained that the soft robot approach is important for delicate underwater operations that require extreme durability with a light touch.

“The soft body of the robot will make it easy to sneak through coral reefs without damaging them,” Li said. “The robot is mainly [intended] for the exploration of ocean, rivers, and lakes, to monitor data like temperature, water density, and chemical components. It can explore the bottom of the ocean, investigate shipwrecks, look for planes that have crashed into the ocean, and monitor creatures under the sea.”

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By employing soft-robot design principles, the underwater bots will be able to handle the wide range of temperatures and atmospheric pressures of deep sea exploration. And while the fishbot can potentially be built with a wide range of materials, including 3D-printed silicone, most of the components can function using transparent gels and plastics.

“Compared to hard and non-transparent robots, this robot is more compatible and adaptive to the environment,” Li said. “The ocean creatures will feel much more comfortable when this robot is quite close to them.”

In terms of far-future scenarios, Li said that the design principles employed are scalable and the bot could potentially be replicated on the microscopic scale. Little fishbots could be deployed in the bloodstream, for instance, as medical sensors or drug delivery systems.

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