Scientists at the Massachusetts Institute of Technology have invented a virtually invisible robot that can swim and pump water in and out of its fingers to power itself.

In a video demonstration, a prototype has been shown stealthily inching toward a fish minding its own business. The mechanical pounced on the unsuspecting creature with surprising agility and gentleness. The fish, while trapped in the robot's claws, appeared to be fine, displaying only a minimal level of alarm.

Inspired By Eels

The fish-grabbing robot is reportedly inspired by glass eels called leptocephali. These organisms hatch in the ocean and migrate to freshwater habitats. The MIT scientists found that they have relevant experiences to share.

"It is extremely long travel, and there is no means of protection," Hyunwoo Yuk, a member of the team, said. "It seems they tried to evolve into a transparent form as an efficient camouflage tactic. And we wanted to achieve a similar level of transparency, force, and speed."

Hydrogel Robotics

The eel led the group to the hydrogel material, which can be obtained by mixing polymer and water. It is this process that rendered the robots transparent, which means they could reflect the color of their background.

Aside from its visual property, the hydrogel material also has the same acoustic property as water. This was depicted in the way the robot fooled the fish into thinking that it is part of the water.

The team of scientists have labored to develop this compound for years. The goal is to produce strong but flexible material. They also want something that will last despite repeated use since previous attempts at fashioning hydrogel robots ended with mechanicals that got brittle over time.


The showcased robot is one of several prototypes developed to work underwater and mimic body organs. There is one that looks like a fin, for instance, capable of flapping itself incessantly. There is also an articulated appendage that can simulate kicking motions, possibly to steer itself forward.

The MIT scientists are not exactly working to create an automaton that can go fishing in your stead. They are also not keen about creating an underwater one either. The team expects the robots to have medical applications, a bit like the previously reported robot that helped a heart beat.

"Hydrogels are soft, wet, biocompatible, and can form more friendly interfaces with human organs," Xuanhe Zhao, another team member, said. "We are actively collaborating with medical groups to translate this system into soft manipulators such as hydrogel 'hands,' which could potentially apply more gentle manipulations to tissues and organs in surgical operations."

Zhao and his team did not explain if they intend to equip the robots with an AI chip so they could gain automated capability. The technology has been explained in more detail through a recently published paper.

ⓒ 2021 All rights reserved. Do not reproduce without permission.