Development of a Residue-Free Peeling Mechanism for Liquid Metal Oxide via Contact Angle Control

A research team led by Professor Wonjung Kim of the Department of Mechanical Engineering at Yonsei University has developed a novel interfacial mechanics mechanism that enables residue-free peeling of the oxide layer formed on liquid metals (EGaIn). This work was carried out through an international collaboration with Dr. Jeong Gon Son of the Korea Institute of Science and Technology (KIST) and Professor Michael Dickey of North Carolina State University (First author: Dr. Sangyun Jung). The research team demonstrated, through combined experimental and theoretical analyses, that the contact angle of the liquid metal plays a critical role in determining the success of oxide layer peeling. When a sufficiently large contact angle is maintained, the oxide layer can be cleanly detached from the substrate without leaving residue. In contrast, at small contact angles, the oxide layer undergoes localized fracture, resulting in residual contamination on the substrate. Nanoscale mechanical analysis near the contact line further elucidated the physical origins of this behavior. Based on this mechanistic understanding, the team also proposed a roll-to-roll transfer printing concept that maintains a large contact angle throughout the peeling process. Using this approach, they experimentally demonstrated damage-free and residue-free transfer of liquid metal patterns. This provides important design guidelines for improving the reliability of liquid metal-based soft electronics and flexible electronic manufacturing processes. This study was conducted as an international collaborative effort, and the results were published in Nature Communications (Impact Factor: 15.7) in December 2025.