Next-generation electronic circuit substrates used in future electronic devices such as soft robots, wearable electronics, and artificial skin must maintain electrical conductivity even when stretched and must resist wetting by water.

Seoyeon Kim, a master's student at Jeonbuk National University (JBNU), Department of Nano Convergence Engineering, advised by Professor Seong-jun Park, has attracted attention by developing an electronic circuit substrate that meets these requirements. The electronic circuit substrate developed by Seoyeon Kim maintains electrical conductivity even when stretched by more than 200%, is not wetted by water, and can be drawn directly by hand.

In the study, the team mixed the liquid metal gallium (melting point 29.8 °C) with magnetic iron particles to formulate a composite material that simultaneously possesses fluidic properties, electrical conductivity, and magnetism. They then applied ultrasonic treatment to develop magnetic particles coated with liquid metal.

By coating these particles onto a stretchable plastic substrate and applying pressure with a pen, electronic circuits can be fabricated directly. The fabricated circuits maintain conductivity even when stretched beyond 200% and do not become wet due to the roughness of the particle surfaces.

Seoyeon Kim stated, 'This research will replace the expensive semiconductor processes previously applied to electronic circuit substrates and serve as a foundational technology for wearable electronic devices, sensors, and smart clothing.'

The research findings were published in the latest issue of the international journal 'ACS Applied Materials & Interfaces' (IF=10.383). As the first author, Seoyeon Kim was selected for the 2022 U.S. training program for Korean female graduate students in science and engineering supported by the National Research Foundation of Korea to conduct applied research on sensors and flexible electronic devices using the developed material and substrate. She is currently conducting research at North Carolina State University in the United States.

This research was carried out with support from the National Research Foundation of Korea's Excellent Young Researcher Program, the Basic Research Laboratory Program, and the NRF's International Cooperation Project.