In the Harry Potter stories, an invisibility cloak can hide a person even while they walk, bend, or run.
In the real world, scientists have long dreamed of creating something similar—materials that can hide objects from detection without being stiff or fragile.
Now, researchers in South Korea have taken a major step toward that goal by developing a new kind of “smart invisibility cloak” that works even when it stretches and moves.
The research was carried out by teams led by Professor Hyoungsoo Kim and Professor Sanghoo Park at KAIST, one of South Korea’s leading science and engineering universities.
Their work was published in Small in October 2025 and was selected as the journal’s cover article.
The new technology focuses on controlling electromagnetic waves, which include radio waves, radar signals, and other forms of energy used to detect objects.
Making something “invisible” in this sense does not mean it disappears from sight. Instead, it means the object no longer reflects or interacts with electromagnetic waves in a way that allows it to be detected.
This is how stealth aircraft reduce their radar signatures. However, traditional materials used for this purpose are rigid metals that cannot stretch. When forced to bend or deform, they crack or lose their function, making them unsuitable for wearable devices or moving robots.
To solve this problem, the KAIST team developed a liquid metal composite ink, known as LMCP. Unlike ordinary metal, this ink behaves more like rubber. It can stretch up to twelve times its original length while still conducting electricity.
Even after being exposed to air for nearly a year, it shows very little degradation, which is a major advantage over existing flexible electronic materials.
The secret lies in how the ink dries. As it dries, tiny liquid metal particles inside the ink naturally connect to form a fine, mesh-like network.
This structure acts as a “metamaterial,” meaning it can be designed to interact with electromagnetic waves in precise ways. As a result, the material combines the softness and flexibility of rubber with the electrical and shielding properties of metal.
The manufacturing process is surprisingly simple. The ink can be printed using standard printers or even brushed onto surfaces, then left to dry at room temperature. There is no need for high heat, lasers, or complex equipment, and the printed patterns remain smooth and uniform.
To demonstrate its potential, the researchers created a stretchable electromagnetic wave absorber. By simply stretching the material, they could change which frequencies of electromagnetic waves were absorbed. This means the cloaking effect can adapt in real time as the material moves.
The technology could lead to major advances in robotic skin, wearable electronics, and future stealth systems.
According to Professor Kim, this work shows that advanced electromagnetic functions can now be achieved using simple printing methods, bringing science fiction concepts like a moving invisibility cloak closer to reality.
