In a new study, roboticists from China reveal a soft robot inspired by deep-sea creatures. This untethered bot is capable of exploring the deep, pressurized depths of the ocean in areas like the Mariana Trench — the deepest oceanic trench on Earth. Its purpose: to better understand this otherworldly ecosystem.
The research was published Wednesday in the journal Nature. It demonstrates one of the first times a small, self-powered robot has successfully swum to such inky depths.
Why it matters — Using soft, cheap, and flexible robots to explore this part of the ocean could be a huge step forward in how marine biologists and other scientists are able to study this elusive part of Earth's geography.
And, because of how life-like this new robot design looks, it could also be used at slightly more accessible depths for sensitive research missions. These are the missions that require being close to marine life, such as studying the coral reefs.
Here's the background — It's common knowledge that Earth's oceans are huge — like 70 percent of the surface of the Earth huge. But it can be difficult to grasp just how deep they really are.
The Mariana Trench, which lies somewhere between Hawaii and the island of Guam, contains the ocean's deepest point at 7 miles deep. This may seem tame compared to the distance to something like the International Space Station, which orbits over 250 miles above us. However, the high pressure seven-miles beneath the ocean's surface make this part of Earth equally (if not much more) difficult to explore than the closest parts of space.
Deep in the Mariana Trench, temperatures hover just degrees above freezing, and the sea creatures who dare to live here experience pressures of eight-tonnes per square inch, which a NASA explains would be "equivalent of an average-sized woman holding up 48 jumbo jets."
With those impressive metrics, it's no wonder that humans and robots alike have struggled to explore this part of the ocean. Technology capable of surviving these conditions is often bulky and expensive, explain the new study's research team.
This team decided that instead of suiting up their robot to protect against pressure, they would borrow the skills of the animals who already call this area home. In particular, the deep-sea snailfish.
While soft-bodied sea creatures like octopuses or jellyfish have already been well-studied for similar robotic biomimicry, less attention has been given to the hadal snailfish. It has a slim body, small flapping 'arms,' and can survive depths of 8,000 meters. They also live in the Mariana Trench — make them an ideal model.
Test trials of the robot swimming freely in a lake.
How it works — When attempting to mimic the snailfish, the researchers were interested in incorporating two key traits:
- Its flapping wings
- Its partly open skull
It's this second feature that inspired a new, pressure-resistant design for the robot's internal electronics.
Typically, electronics are tightly bundled together with less than 1 millimeter of space between them. But in their trials, the research team found these close interactions between onboard electronics, such as those powering the robots' wings, are especially susceptible to pressurized failure.
To circumvent this, they designed an electronic system that could be further apart (over 2 millimeters) and distributed through the robot's silicon body. With this trick onboard, the robot was able to better withstand oceanic pressures and could easily drive its own wings with electronic "muscles" powered by lithium-ion batteries — the same tech likely powering your computer right now.
The robot swimming freely in the Mariana Trench.
What they did — The team started testing their new robot in low-stakes environments first, like a laboratory water chamber and a lake. But it was soon ready for the big leagues: the South China Sea and the Mariana Trench.
After an assist from a deep-sea craft to get the robot down to appropriate depths, the researchers report that it was able to swim at both two miles and nearly seven miles deep for a sustained amount of time (up to 45 minutes in some trials.)
What's next — Despite the success of this bot's first plunge into the deep end of the ocean, it may still be a while before these kinds of self-powered robots fill the ocean.
One issue pointed out by a companion essay published alongside the research is the delicateness of the robot itself. While it may be good at deftly infiltrating the ranks of sea-life, it could also be easily swept away by a changing ocean current.
In the future, these small bots could help scientists study everything from biodiversity to coral reef health and pollution — all thanks to inspiration from the creatures that call the deep-sea home.
Abstract: The deep sea remains the largest unknown territory on Earth because it is so difficult to explore. Owing to the extremely high pressure in the deep sea, rigid vessels and pressure-compensation systems are typically required to protect mechatronic systems. However, deep-sea creatures that lack bulky or heavy pressure-tolerant systems can thrive at extreme depths. Here, inspired by the structure of a deep-sea snailfish, we develop an untethered soft robot for deep-sea exploration, with onboard power, control and actuation protected from pressure by integrating electronics in a silicone matrix. This self-powered robot eliminates the requirement for any rigid vessel. To reduce shear stress at the interfaces between electronic components, we decentralize the electronics by increasing the distance between components or separating them from the printed circuit board. Careful design of the dielectric elastomer material used for the robot’s flapping fins allowed the robot to be actuated successfully in a field test in the Mariana Trench down to a depth of 10,900 metres and to swim freely in the South China Sea at a depth of 3,224 metres. We validate the pressure resilience of the electronic components and soft actuators through systematic experiments and theoretical analyses. Our work highlights the potential of designing soft, lightweight devices for use in extreme conditions.