Soft robotics is a growing field that uses flexible, bendable materials instead of rigid machines.
These soft systems are especially promising for underwater tasks where gentle but firm handling is needed, such as collecting samples, repairing marine structures, or even helping with delicate medical procedures.
A new breakthrough inspired by starfish could push this technology much further.
In the natural world, many creatures have clever ways of sticking to surfaces underwater.
Geckos grip with tiny hairs on their feet, mussels cling tightly using natural glue-like proteins, and octopuses rely on suction cups.
All of these systems are reversible, meaning they can attach and release whenever needed. Inspired by these examples, researchers have been searching for new ways to give robots similar abilities.
Now, a team of scientists from Korea and the United States, led by Professor Hyunsik Yoon at Seoul National University of Science and Technology, has created artificial “tube feet” that mimic the way starfish move and grip.
Their research, published in Science Advances, shows how these starfish-inspired structures can attach and detach underwater on demand, without relying on messy adhesives.
Starfish are remarkable animals. With their tube feet, they can crawl across rocks, cling to rough surfaces, and even dig into sand.
To replicate this, the researchers designed an artificial version using two connected cylindrical parts with different properties. The soft, hydrogel “mouth” of the foot changes shape when it swells in water, transforming into a cupped pad that spreads across a surface.
This action creates a tight seal. When the foot detaches, a vacuum forms inside the tube, producing a surprisingly strong grip—up to 65 kilopascals of force, which is more than enough to handle rocks or heavy objects underwater.
Just like starfish feet, the artificial version can let go quickly and cleanly. The release can be triggered by outside changes in the environment or by pneumatic actuation, which uses air pressure to switch the foot off. In experiments, the researchers demonstrated the technology by making their device pick up and move rocks underwater.
The potential applications are wide-ranging. In the electronics industry, the precise grip could be used to transfer tiny chips in MicroLED manufacturing, helping build brighter, more energy-efficient displays for smartphones, TVs, and wearable devices.
In medicine, the same glue-free adhesion could lead to patches, sensors, or surgical tools that stick firmly to wet skin or tissue without causing irritation, offering patients more comfort and safety.
Professor Yoon explains that this combination of strong adhesion and easy release could make future devices not only smarter but also more user-friendly. By borrowing a trick from starfish, engineers may have found a simple and elegant solution to one of the toughest challenges in underwater robotics.
