Shape memory polymers with nanotips help solve micro-LED chip transfer problem

A research team at Pohang University of Science and Technology (POSTECH), has developed a novel dry adhesive technology that allows everything from microscale electronic components to common household materials to be easily attached and detached.

The study was recently published in the journal Nature Communications, and the team was led by Professor Seok Kim in collaboration with Professor Kihun Kim (POSTECH), Professor Namjoong Kim (Gachon University), Professor Haneol Lee (Chonbuk National University), and Dr. Chang-Hee Son (University of Connecticut, U.S.).

Micro-LEDs, a next-generation display technology, offer significant advantages such as higher brightness, longer lifespan, and the ability to enable flexible and transparent displays. However, transferring micro-LED chips—thinner than a strand of hair—onto target substrates with high precision and minimal residue has been a persistent challenge. Conventional methods relying on liquid adhesives or specialized films often result in overly complex processes, poor alignment accuracy, and residual contamination.

In addition, researchers have struggled with the so-called adhesion paradox—the theoretical prediction that surfaces should strongly adhere at the atomic level, contrasted by the real-world difficulty of achieving strong adhesion due to surface roughness that limits actual contact area.

The POSTECH team ingeniously leveraged this paradox. Their solution lies in the use of shape memory polymers (SMPs) featuring densely packed nanotips. At room temperature, the surface remains rough, exhibiting low adhesion. When heated and pressed, the surface smooths out—much like ironing wrinkles—and achieves significantly stronger adhesion. Upon reheating, the surface returns to its original rough state, drastically reducing adhesion and enabling easy release.

This technology provides over 15 atmospheres of adhesion strength during bonding and near-zero force detachment through a self-release function. The difference in adhesion strength between the “on” and “off” states exceeds a factor of 1,000, outperforming conventional approaches by orders of magnitude. The team demonstrated precise pick-and-place of micro-LED chips using a robotic system, and confirmed stable adhesion even with materials such as paper and fabric.

“This innovation allows for the precise manipulation of delicate components without the need for sticky adhesives,” said Professor Seok Kim of POSTECH. “It holds significant potential for applications in display and semiconductor manufacturing, and could bring about transformative changes when integrated with smart manufacturing systems across various industries.”