Article by Kanawas Sriprab (Khun), on 4 August 2023 at 05:10 am PDT

Reseachers at U.C. San Diego have recently developed a prototype of an Eel-robot capable of swimming in the ocean like, well, an eel. The development has become a breakthrough in biomimicry and soft robotics; so why is this relevant to us?

Underwater robots:

Underwater robots have been in use both commercially and by governments for years, for example, the fossil fuel industry utilises these robots to construct their offshore platform structures and pipelines and scientists employ them for scientific research into areas unreachable by humans.

There is a catch however, marine robots are often noisy, and can disturb the fragile ecosystem in the oceans. They are also made of frigid metal parts, which can damage the undersea life and habitat via scraping or cutting.

Biomimicry and soft robotics:

Enter biomimicry, a perceived solution to the researcher's problem. Biomimicry employs the use of naturally (usually biologically) existing systems, and recreates them in order to solve human issues. This can include examples such as the development of mechanical arms, which are structurally made up of joints that we may see in human, or animal arms.

Soft robotics is a subsidiary field of robotics, which attempts to build robots out of non-rigid and soft materials, allowing for versatile motion, among other advantages.

The material:

Researchers at U.C. Sandiego set out to build the robot with inspiration based on eel larvae, as they found the wavelike motion to be ideal for coral exploration and the transperancy allows for camouflage. 

"To create their eel-inspired robot, the researchers used transparent dielectric elastomer actuators (DEAs)—"pieces of rubber that respond to an electrical stimulation," Christianson explains. While the rubber itself doesn't conduct electricity, a voltage applied to the upper and lower surfaces of the elastomer causes it to flatten, making the material both thinner and longer." - TheScientist interview with Caleb Christianson, a researcher who has been working on the prototype.

After comparing the real-life eel larvae and the robot in regards to transparency the results were positive, suggesting that the robot was in fact transparent as intended! This solves the issue of scaring away ocean wildlife.

The motion:

The wave-like motion is produced using electrodes, positioned inside the DEAs.

To achieve more-fluid motion and improve propulsion, the team next placed three of these actuator pairs end-to-end, creating a 22-cm-long, 5-cm-high, and 1.5-mm-thick robot. - TheScientist

The electrodes produce an undulating (smooth up and down) motion underwater.

Motion of an eel in nature.

The use:

The eel-inspired robot is designed for the exploration of coral reefs, a crucial part of the ocean ecosystem, providing a habitat for fish nurseries and protect coasts from water erosion. Coral are extremely fragile and threatened organisms, which means that the ability to study them further, with a robot that will not endanger them is highly advantageous to their conservation, and for gaining more data to educate others in their protection.

What's next?

• The device still has to go through a few upgrades before ocean use, due to the relatively low seed at 1.9 mm/s (forward).
• Due to the issue mentioned above power consumption could be an issue.
• Competition with existing models is also an issue due to the "traditional" devices allowing for remote operation, ability to stay for long durations in water, and sensors/cameras, which can record more variables, such as temperature or pH.

Why is this relevant for the future of science?

While it may seem that there are still many miles to go for the eel robot, it has truly served as a testament to the rapidly improving technological possibilities in robotics and engineering. This new prototype is opening doors to the future possibilities of marine exploration and research along with the possibility of the wider uses of soft robotics, in fragile tasks.

The outlook is bright and the engineering community looks towards the future of the eel robot, and soft robotics!

General Information from: TheScientist