SNU College of Engineering (Dean Cha Kook-Heon) announces that the SNU-KIST joint research team (1^st Author: Doctor Byun Junghwan, Corresponding Authors: SNU Professor Hong Yongtaek of the Department of Electrical and Computer Engineering and Senior Researcher Chung Seungjun of KIST) has succeeded in developing an elastic media that stretches like the skin and flexibly modulates its electrical, mechanical and surface-morphological properties.
 
Along with the development of IoT (Internet of Things), there is a growing interest in body-attachable and wearable electronics. A limitation of the conventional semiconducting materials for wearable devices are that their electrical performances decline under mechanical stress that form whilst stretch. Therefore, a research on elastic media is demanded to optimize the operational stability of electric devices.
 
Active researches are being conducted on methods to alter the pattern, thickness, and composition of elastic thin-film materials to thus minimize the hindrance of mechanical stress. However, these studies still have not managed to overcome the difficulty of polymer processing on substrate, restriction in the range of elastic material that can be applied, and the instable electrical, mechanical, optical, and surface-morphological properties of thin-film materials under a stretch or compression.
 
SNU-KIST team responds to these limitations by explaining a mechanism that tailors the properties of thin-film materials with their development of the new elastic platform. The skin-like, thin-film properties of team’s new media can be attributed to its composition of inkjet-printed microlattices.
 
A periodically-controlled, mechanical strain distribution forms on the surface of elastic media due to the periodic difference in the Young’s modulus distribution between it and the stretchable substrate. The properties of the thin-film under stretch is moderated as new arbitrary film form on the elastic media to be influenced by the media’s strain distribution; using its memory of this influence, the properties of film are manipulated.
 
One highlight of the team’s findings is the discovery that the design (i.e. size and period) of the material that is inserted inside the media can control the properties of thin-film. The team has also revealed through experiments and simulations that various properties of metal, oxidized, and organic thin-films can be freely controlled. The work is said to have opened a new avenue for demonstrating possibilities to design a high-reliability, elastic media via the property manipulation of thin-film during stretch.
 
This research has been conducted with the support of the Skintronics Research Project of the Institute for Information & Communications Technology Promotion and the KIST Institute Specific Project of the Ministry of Science and ICT (under Minister You Young Min).
 
The findings have decorated the back cover of the recent issue of Advanced Materials of October 4^th.