'Stealth film' thinner than a strand of hair blocks 99.9999999% of electromagnetic waves

South Korean researchers have developed a "stealth film" far thinner than a human hair that blocks more than 99.9999999% of electromagnetic waves and can evade detection by thermal imaging cameras. The material is expected to find broad use in future weapons systems — including fighter jets and unmanned aerial vehicles — as well as in aerospace, 5G and 6G communications, and wearable electronics.

A research team led by Kim Tae-hoon of the Korea Institute of Materials Science (KIMS) Convergence Materials Research Division, working jointly with teams led by Kim Seon-jun and Kim Jae-woo of the Korea Institute of Science and Technology (KIST), developed an ultra-thin composite film that simultaneously achieves electromagnetic shielding, infrared stealth and high mechanical strength by combining carbon nanotube (CNT) fiber with MXene.

As advanced weapons systems and electronics grow more sophisticated, the need for lightweight, flexible materials capable of blocking both infrared detection and electromagnetic threats has intensified. Conventional metal shielding materials, however, have long been hampered by their weight, susceptibility to corrosion and lack of flexibility.

Carbon nanotube fiber — a leading alternative — is light, strong and highly effective at shielding electromagnetic waves, but its thread-like form makes it difficult to produce as a wide film, and it emits high levels of infrared radiation. MXene, a two-dimensional nanomaterial, has the opposite profile: its low infrared emissivity makes it well suited for stealth applications, but it falls short on mechanical strength and long-term stability.

The research team addressed this by combining the two contrasting materials in a structure likened to "bricks and cement" in a building.

The team first introduced amine functional groups onto the surface of the CNT fibers to enable bonding with MXene, then continuously drew the fibers through a MXene solution and wound them side by side to form a film. In the resulting structure, the aligned CNT fibers act as the "bricks" while the MXene filling the gaps between them serves as electrically conductive "cement."

This architecture prevents the CNT fibers from sliding against one another, boosting mechanical strength, while creating an uninterrupted electrical pathway throughout the film that enhances electromagnetic shielding performance. The MXene coating on the surface suppresses infrared emission, reducing the likelihood of detection by thermal imaging and other infrared sensing equipment.

The performance becomes even more striking when the film's thickness is taken into account. At just 17.5 micrometers — roughly one-fifth the diameter of a human hair — the material is exceptionally thin.

Yet it recorded electromagnetic shielding performance of approximately 90 decibels (dB) across communications and radar frequency bands, sufficient to block more than 99.9999999% of incoming electromagnetic waves.

The film achieved a tensile strength of 1.02 gigapascals (GPa), matching the mechanical properties of high-strength steel. It also suppressed infrared emission and, compared with conventional MXene films, maintained stable performance under high-temperature, high-humidity conditions and repeated bending.

The researchers believe the film could serve as a multifunctional stealth material for fighter jets, unmanned aerial vehicles and drones, blocking electromagnetic interference while reducing the risk of infrared detection. It could also be applied to electromagnetic shielding in 5G and 6G communications devices, as well as next-generation consumer electronics such as wearables and foldable devices.

"The key to this technology is combining nanomaterials with different properties — like bricks and cement — so that the strengths of each material are preserved while their weaknesses are offset," Kim Tae-hoon said. "We expect it to be widely used as a multifunctional material that addresses electromagnetic challenges in future weapons systems and aerospace applications, as well as in next-generation communications devices and wearable electronics."

The findings were published in Advanced Composites and Hybrid Materials, an international journal in the field of composite materials.