Researchers build first 3D thermal cloak to hide objects from heat

Researchers have developed the first 3D thermal cloak capable of rendering objects invisible to heat from any direction, marking a breakthrough in thermal engineering and materials science. The device, created by a team led by Shelly Zhang at the University of Illinois Urbana-Champaign, uses a hybrid material structure to guide heat around an object, making it undetectable to infrared cameras while maintaining internal temperature stability. This advancement overcomes limitations of previous thermal cloaks, which were restricted to two dimensions or single-direction heat flow.

The cloak’s design relies on a lattice-based material that can be adjusted in three dimensions to control thermal conductivity. A 3D-printed aluminum lattice, acting as a high-conductivity medium, is combined with a rubber-like material of low thermal conductivity. This hybrid structure forces heat to bypass the cloaked object entirely, creating the illusion that the object does not exist in the thermal field. Laboratory tests demonstrated the device’s ability to conceal complex 3D geometries, including head-like shapes, under temperature gradients. Infrared imaging showed the cloaked region appeared as a uniform temperature, while the object inside remained protected from external extremes.

“A real thermal cloak should work no matter where the heat comes from,” Zhang said. “Our device can hide a complex 3D object in an infinite number of directions while keeping the temperature inside stable and protected.” The team’s approach builds on transformation thermotics, a theoretical framework that predicts the manipulation of heat flow. By creating a material with graded and anisotropic thermal properties, the researchers achieved a physical realization of this concept, a feat previously unattainable in three-dimensional space.

The technology has broad applications, from protecting sensitive electronics and managing heat in microchips to defense uses such as thermal concealment. The researchers envision future iterations that could actively manipulate heat, such as concentrating or distributing it within the cloaked region. For example, they aim to develop cloaks that can mask objects generating their own heat, requiring precise control over heat flow. “We’ve shown that a true 3D omnidirectional thermal cloak is possible,” Zhang said. “The next step is to make cloaks that don’t just hide and protect but also actively manipulate heat in useful ways.”

While the Illinois team’s work focuses on passive thermal management, other studies highlight complementary approaches. A thermoelectric device described in a separate Nature paper uses active cooling to achieve thermal concealment, operating across a wide temperature range and responding rapidly to changes. This device integrates infrared camouflage, deception, and information display, with potential applications in military and surveillance contexts. Meanwhile, researchers at Zhejiang University in China developed a dual-layer cloak that scatters both heat and electrical energy, offering solutions for reducing static in electronics and improving thermophotovoltaic efficiency.

The implications of these advancements extend beyond technical applications. The ability to control heat as a form of “information” opens new possibilities for thermal communication and protection. Zhang emphasized that the work is not limited to hiding objects but also involves “hiding and protecting information carried by heat.” This could revolutionize fields where thermal signatures are critical, such as cybersecurity or data transmission.

The research, supported by the National Science Foundation, the Villum Foundation, and the Air Force Office of Scientific Research, represents a significant step toward practical thermal cloaking. While the current device is a laboratory prototype, its success paves the way for scalable solutions. As the team continues refining the technology, the line between theoretical physics and real-world application grows thinner, promising transformative impacts across science and industry.