Robotic fish could unlock mysteries of life at bottom of world’s deepest ocean

HANGZHOU, China — A self-powered robot inspired by a fish could unlock the mysteries of life seven miles down at the bottom of the world’s deepest ocean. The robotic fish wiggles its body and flaps its fins just like the real thing and is set to improve exploration of the uncharted seas.

The robot, described in the prestigious British journal Nature, is the most advanced of its kind ever built. It’s based on the pink snailfish, which lives in the Mariana Trench, an abyss in the western Pacific Ocean almost seven miles beneath the waves. The idea is that it won’t freak out underwater creatures, many of which are still to be discovered — they will assume it’s just another fish.

“In trials, the robot was found to operate successfully there,” says corresponding study-author Tiefeng Li of Zhejiang University, per South West News Service. “It also swam freely up to two miles below the surface in the South China Sea.”

Fish robot
Video of free-swimming soft robot in deep sea. This video shows the deep-sea free-swimming of the soft robot in the South China Sea. The soft robot was grasped by a robotic arm on HAIMA ROV and reached the bottom of the South China Sea (mean depth: 3,976 feet). After the release, the soft robot was actuated with an onboard AC voltage of 8 kV at 1 Hz and demonstrated free-swimming locomotion with its flapping fins. The front view and side view of the swimming process were recorded by the cameras and LED lights on the ROV. (Zhejiang University)

The oceans contain 99 percent of the living area on the planet. Yet they are so hard to explore that scientists know more about space. That could be about to change. As climate change and overfishing wreak havoc on oceans, scientists are racing to study marine life in detail.

Mounted on a lander, an “underwater elevator,” the robot reached the bottom of the Mariana Trench. It was filmed by deep-sea cameras and LED lights in anti-pressure shells flapping its fins and wiggling its body.

The untethered device is similar in size and color to an actual snailfish, almost nine inches long with an eleven-inch wingspan. Lightweight activators move “muscles” and an “elastic frame.” It has a top speed of just a quarter of a mile an hour in the deep and is four times faster in shallower waters.

“The design is guided by the body features of snailfish. The electronics — including a lithium-ion battery and a high-voltage amplifier — are embedded in a soft silicone matrix,” explains professor Li. “It has a relatively low density — beneficial for deep-sea swimming. The flapping fins, each with two membranes, are powered by the compact high-voltage amplifier. The ground end of the amplifier is connected to a power consumption resistor and the surrounding water.”

Robotic fish’s journey to the bottom of the ocean

The bizarre-looking snailfish, a suction feeder that detects prey with sensors on its head, is the world’s deepest-living known fish. “The deep sea remains the largest unknown territory on Earth because it is very difficult to explore,”  adds Li. “The extremely high pressures in this environment mean mechanical systems usually require rigid vessels and pressure compensation systems in order to operate. However, deep-sea creatures — like jellyfish — lack bulky or heavy pressure-tolerant bodies yet still thrive at extreme depths.”

Inspired by the structure of the snailfish, Professor Li’s team developed the deep-sea robot with onboard power, control, and the ability to propel itself through the water. “Unlike some swimming robots whose movement is dependent on stiff, bulky vessels, the electronic components of this robot are decentralized and encased in a flexible, silicone matrix,” he says. “Field tests in the Mariana Trench up to 10,900 meters in depth and the South China Sea up to 3,224 meters revealed the excellent pressure resistance and swimming performance of the robot.”

The video shows the potential of soft robots in deep-sea exploration. (Zhejiang University)

To build better aquatic robots, researchers have mimicked tuna, jellyfish, and lobsters, and they’ve also built robots out of pliable materials. But they have never mimicked a creature so remote or obscure, which is capable of going further than any other.

In addition to the deep-sea field tests, a series of experiments in a pressure chamber and a deep lake further underlined the robot’s unique swimming skills. “Future work will focus on developing new materials and structures to enhance the intelligence, versatility, maneuverability, and efficiency of soft robots and devices,” says Li.

Robotics experts Professor Cecilia Laschi of the National University of Singapore and Dr. Marcello Calisti of the University of Lincoln, England, described the feat as “remarkable”. It lays the foundations for future generations of deep-sea explorers in which soft robots safely navigate coral reefs or underwater caves, to collect delicate specimens without damaging them.

“Swarms of underwater soft robots, with the ability to crawl on the seabed, anchor themselves on to specific structures, or swim over particular areas, could contribute to the development of technologies for various other applications,” the robotics experts says. “These might include monitoring the ocean, cleaning up and preventing sea pollution, or preserving marine biodiversity. More fundamentally, they could help researchers to explore the vast uncharted depths of the oceans.”

SWNS writer Mark Waghorn contributed to this report.

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