Prof. Yongtaek Hong, Awaiting release of wearable devices that perform even when twisted (Donga Science, 20181003)

2018-10-10l Hit 30

The physical, mechanical properties of the thin-film are being controlled using an elastic electronic device platform

Domestic researchers developed a wearable electronic device platform that can stretch easily like the human skin and, without restraint, disperse the force inflicted on the device during deformation. This seems to have paved the way for developing wearable devices that function stably without a drop in performance even when twisted.

On the 3rd, it was announced that the research team of Seungjun Chung, Senior Research Scientist at KIST(Korea Institute of Science and Technology) Photo-Electronic Hybrids Research Center, collaborated with the research team of SNU ECE professor Yongtaek Hong and successfully developed an elastic electronic device platform that can freely control the various electric and mechanical properties and formation of the thin film.

Recently, elastic wearable electronic devices that can be attached to the human body are drawing attention, but there is a problem. In the case of pre-existing semiconductor devices, the mechanical stress that occurs when they are stretched or contracted affects the functional thin film device, leading to performance degradation.

To resolve this problem, within the film that is thin like skin and has high elasticity, researchers inserted transparent structures with high strength to act as cushions. In other words, transparent structures that are tens of micrometers(㎛·1㎛ is 1 millionth of 1m) in dimension are regularly arranged with fixed gaps in between.

Then, between the elastic film and the inserted structure, there is a patterned difference in modulus of elasticity, or put differently, a difference in ‘Young’s modulus’(a modulus of elasticity that indicates the extent of deformation and elongation when an object is stretched from both sides). Thus, if mechanical stress is externally inflicted, the mechanical stress distribution can be determined by observing the distribution change in elasticity difference. This combined structure is also easy to manufacture using a printing-like process similar to that of a printer.

Based on such research, the team revealed that depending on the structure’s solidity, strength, and the lattice configurations, it is possible to control the mechanical stress that the thin film device receives when flexed. Also, the mechanical stress of a given area can be concentrated or dispersed. It has been ascertained that such control technology can be applied to various types of thin-films including metal, oxide, and organic matter.

Researcher Chung expects that through this research, not only will it be possible to control the change in thin film characteristics that occurs during deformation but also to improve the reliability of electronic devices such as strain-sensitive wearable display and sensors.

The research results were first published online in the international journal ‘Advanced Materials’ on August 21st and was chosen as the cover paper for the latest issue.

Translated by: Jee Hyun Lee, English Editor of Department of Electrical and Computer Engineering