Professor Kim Seok and his research team from Pohang University of Science and Technology POSTECH developed a new adhesive technology that allows for easy attachment and removal of electronic components smaller than a hair strand, as well as everyday items, in collaboration with Professor Kim Ki-hoon from the Department of Mechanical Engineering, Professor Kim Nam-jung from Gachon University, Professor Lee Han-eol from Jeonbuk National University, and Postdoctoral Researcher Son Chang-hee from the University of Connecticut.
The next-generation display technology known as "micro light-emitting diodes (LEDs)" is receiving significant attention for being brighter and longer-lasting than existing screens, and for its capability to implement flexible or transparent displays. However, attaching LED chips that are much smaller than the thickness of a hair to precise locations, or cleanly detaching them when needed, has proven to be much more challenging than expected. Previously, liquid adhesives or special films were used, but they posed issues with complexity, lower precision, and residue.
Moreover, scientists have long faced the challenging problem known as the "Adhesion Paradox." This phenomenon suggests that, theoretically, objects should stick strongly at the atomic level, but due to uneven surfaces, the actual contact area is small, leading to a weaker adhesive force. It is a paradoxical situation where materials should adhere well but often do not.
The research team discovered a clever adhesive technology that actually utilizes this "Adhesion Paradox." The key is to precisely create sharp protrusions measuring nanometers (10^-9 meters) on a special material called "shape memory polymer (SMP)." Normally, the surface is rough and has weak adhesion, but after applying heat and pressure, the surface becomes flat as if it has been ironed, resulting in significantly increased adhesive strength. Conversely, applying heat again returns the surface to its original rough state, reducing adhesion and allowing for easy detachment. This is a dry adhesive technology that sticks firmly when applied and pops off effortlessly when removed.
This technology generates strong forces of about 15 atmospheres when attaching and has the ability to fall off naturally without extra force during detachment. The difference in adhesive strength between attachment and detachment is over 1000 times, making it significantly superior to existing technologies. Using this technology, the research team successfully attached micro LED chips to a display substrate with precision using robots and demonstrated stable handling of materials like paper and fabric.
Professor Kim Seok noted, "This technology can precisely handle devices without adhesives, which will be practically beneficial for the display and semiconductor industries. It can be applied across almost all industrial adhesive processes, and when combined with smart manufacturing technology, it could bring significant changes throughout the industry."
This research was published in the online edition of the international journal "Nature Communications" on May 28.
References
Nature Communications (2025), DOI: https://doi.org/10.1038/s41467-025-60220-7