Soft robotics, which uses flexible and deformable materials, is an emerging field in autonomous systems. It has recently been applied to next-generation tasks such as deep-sea sampling with soft robotic grippers—requiring strong adhesion and autonomous detachment. Bioinspired adhesion offers a promising solution. In nature, gecko feet, mussel proteins, and octopus suction cups achieve efficient, reversible adhesion for underwater tasks like object pickup, movement in tight spaces, and surface attachment. Inspired by these, researchers have developed switchable underwater adhesion methods using chemical bonding, suction, negative pressure, and capillary forces.
Taking ahead the research work in this direction, a team of researchers from Korea and the USA, led by Professor Hyunsik Yoon from Chemical and Biomolecular Engineering at Seoul National University of Science and Technology, has successfully developed starfish-inspired tube feet for temporary and switchable underwater adhesion and transportation. Their work was made available online and has been published in Volume 11, Issue 30 of the journal Science Advances on July 23, 2025.
"Our starfish-inspired technology can attach and detach underwater on demand, just like real starfish tube feet. Starfish, a type of echinoderm, can move on rocks, adhere to rough surface, dig and burrow into sand, and toss sand grains. This innovation could transform underwater robots, marine repairs, and medical devices by providing a strong grip without using chemical adhesives," remarks Prof. Yoon.
The starfish-inspired tube foot—designed via combining two serially bonded cylindrical components with different mechanical properties—comprises a soft hydrogel mouth and a rigid stem. Its underlying mechanism is as follows: the straight hydrogel cylinder selectively changes its shape to a soft and cupped pad upon swelling. The pad modifies itself to stretch and spread on contact. Eventually, this transformation facilitates the desirable adhesion of the foot to target surfaces. Notably, the formation of a vacuum within the tube during detachment results in a strong underwater adhesion force as high as 65 kPa.
The proposed artificial tube feet exhibit high adhesion hysteresis, automatic release based on outside stimuli, and quick detachment by pneumatic actuation. In this study, the researchers demonstrate the functionality of their temporary underwater adhesive inspired by the tube feet of starfish through underwater manipulation of rocks.
This starfish-inspired underwater adhesion technology is expected to enable a wide range of real-world applications. The reversible, glue-free grip could enable precise chip transfer in MicroLED manufacturing, as well as temporary yet secure attachment for biomedical patches and surgical tools in wet environments. By combining strong adhesion with easy release, this innovation offers a versatile solution across industrial and healthcare fields.
"The starfish-inspired adhesion technology could play a pivotal role in advancing both display manufacturing and biomedical engineering. In the display industry, its precise, controllable grip could enable highly reliable chip transfer in MicroLED production, helping to create brighter, more energy-efficient screens for smartphones, wearables, and large displays. In healthcare, the same reversible, glue-free adhesion could lead to next-generation biomedical patches, wearable sensors, and surgical tools that attach securely to wet skin or tissue without irritation, improving patient comfort and treatment outcomes," elaborates Prof. Yoon on the potential applications of their research.
Overall, by offering a strong yet gentle attachment method, the present work could help make future devices thinner, smarter, and more user-friendly.
