KAIST

<(From left) Dr. Osman Gul, Distinguished Professor Inkyu Park, Dr. Hye Jin Kim>

What if electronic circuits could be created simply by drawing lines with a pencil on paper or leaves—and then immediately applied to soft robots or skin-attached health monitoring devices? Korean researchers have developed an electronic materials technology that forms electrically conductive liquid metal in a fine powder form, allowing circuits to be drawn directly on a wide variety of surfaces. This technology presents new possibilities for next-generation flexible electronics, including applications on paper and plastic as well as in soft robotic systems and wearable devices.

KAIST (President Kwang Hyung Lee) announced on the 15th of March that a research team led by Distinguished Professor Inkyu Park from the Department of Mechanical Engineering, in collaboration with Dr. Hye Jin Kim’s team at the Electronics and Telecommunications Research Institute (ETRI, President Seungchan Bang), has developed a liquid metal powder–based electronic material technology that allows electronic circuits to be directly drawn on desired surfaces.

The material the researchers focused on is liquid metal, which flows like a liquid yet conducts electricity like a metal. However, conventional liquid metals have very high surface tension and poor wettability on most surfaces, making it difficult to create precise circuits at desired locations. They tend to spread or clump easily, requiring additional surface treatments or processing steps that limit practical applications.

To overcome these limitations, the research team developed a new approach that converts liquid metal into fine powder particles. Each particle consists of liquid metal encapsulated by a thin oxide shell. Under normal conditions, the powder does not conduct electricity. The oxide layer forms naturally when the metal reacts with oxygen in the air, creating a very thin protective film. However, when light mechanical stimulation—such as brushing with a paintbrush or pressing with a finger—is applied, the oxide shell breaks and the metal particles connect with one another, enabling electrical conductivity.

<Demonstration Video>

In other words, the powder can be applied to a surface and only the required areas can be pressed to “activate” the electronic circuit, overcoming the spreading and patterning difficulties associated with conventional liquid metal circuits.

One of the most notable features of this technology is its versatility across locations and materials. Without requiring any thermal processing, circuits can be created instantly on surfaces such as paper, glass, plastic, textiles, and even living plant leaves. The method significantly reduces issues such as spreading, sedimentation, and pattern distortion that were common in conventional liquid metal circuits, enabling stable circuit fabrication on diverse surfaces.

Using this technology, the research team demonstrated practical applications including skin-mounted wireless health monitoring devices and flexible circuits for soft robots that can freely change shape. Because precise circuits can be fabricated on many surfaces without complex equipment, the technology is expected to find applications in next-generation electronic systems such as wearable healthcare devices, soft robotics, and flexible electronics.

The technology also offers advantages in terms of environmental sustainability. After use, the circuits can be dissolved in water and chemically treated (for example with sodium hydroxide, NaOH) to recover the liquid metal. The recovered metal can then be converted back into powder form and reused. This capability makes the technology an environmentally friendly approach that can help reduce electronic waste.

The powder also demonstrates stable performance. According to the research team, the developed powder maintains its functionality even after being stored at room temperature for more than a year and remains electrically intact after tens of thousands of bending or twisting cycles. These characteristics make it suitable for temporary electronic circuits that disappear after use as well as for customizable electronic devices.

<Research Image(AI-generated image)>

Distinguished Professor Inkyu Park stated, “This research enables electronic circuits to be fabricated as intuitively as drawing a picture, while also allowing recycling of the materials,” adding, “We expect it to be applied across various fields, including wearable computers and adaptive IoT systems that can change shape.”

This research was led by Osman Gul, a postdoctoral researcher in the Department of Mechanical Engineering at KAIST, as the first author. The study was published online on December 9, 2025, in the international journal Advanced Functional Materials. The work was also selected as the Back Cover article of the journal in recognition of its significance.
※ Paper title: “Mechanochemically Activatable Liquid Metal Powders for Sustainable, Reconfigurable, and Versatile Electronics”, DOI: https://doi.org/10.1002/adfm.202527396

This research was supported by the Mid-Career Researcher Program of the National Research Foundation of Korea (NRF) funded by the Ministry of Science and ICT, as well as by a project supported by the Korea Evaluation Institute of Industrial Technology (KEIT).