KAIST Develops Variable Stiffness Device for Adaptive Applications. (Image courtesy of KAIST)
SEOUL, June 5 (Korea Bizwire) — A joint team of researchers from KAIST and Seoul National University has developed a groundbreaking liquid metal ink capable of shifting between rigid and flexible states depending on temperature, paving the way for next-generation wearable devices and medical implants.
The team, led by Professor Jung Jae-woong of KAIST’s Department of Electrical Engineering, Professor Steve Park of KAIST’s Materials Science and Engineering Department, and Professor Park Sung-joon of Seoul National University, announced the findings on Wednesday. Their work was published in the May 30 edition of Science Advances.
At the heart of the innovation is gallium, a metal that melts at around 29.8°C — near human body temperature. While gallium is solid and hard at room temperature, it becomes soft and fluid when warmed, offering a wide range of mechanical flexibility.
However, the material’s tendency to clump into droplets and its instability in liquid form have historically made precise circuit printing difficult.
The team overcame these challenges by developing a method to control gallium’s pH level. By dispersing micrometer-scale gallium particles into a neutral solvent mixed with polymers, they created a stable ink suitable for high-resolution, room-temperature printing.
During the heating process, the solvent becomes acidic, stripping the oxide layer from the gallium particles and activating their conductivity.
The result is a printed electronic circuit that can dynamically shift from a plastic-like rigidity to a rubber-like softness — ideal for flexible electronics.
To demonstrate the material’s versatility, the researchers developed a wearable health monitor that remains rigid during handling but softens when worn. They also tested the ink in a brain probe application, where it remains firm during insertion but softens within brain tissue to reduce inflammation.
“This research solves long-standing challenges in liquid metal printing and opens the door to ultra-precise, room-temperature circuit fabrication,” said Professor Jung. “It has broad applications across multipurpose electronics, medical technologies, and robotics.”
The study marks a significant step toward reconfigurable electronic devices that adapt to their environments — whether worn on the body or integrated into sensitive medical procedures.
M. H. Lee (mhlee@koreabizwire.com)
