A three-dimensional thermal cloak that can conceal objects from heat, while also shielding them from extreme temperatures, has been developed by researchers in a breakthrough with significant potential for quantum electronics and military stealth technologies.
The breakthrough, led by University of Illinois Urbana-Champaign civil and environmental engineering professor Shelly Zhang in collaboration with colleagues at the Technical University of Denmark, differs from past thermal cloaks that only function in two dimensions, or in a single direction.
The team’s new device is capable of guiding heat around an object, regardless of the origin point of the heat source. When used with an infrared camera, the cloaked object effectively disappears, while the temperature inside the protected region remains stable.
The team’s achievement was detailed in a new study published in Nature Communications.
A Novel Approach to 3D Thermal Cloaking
Unlike previous thermal cloaks, which only worked in two dimensions or from a single direction, the new device guides heat around an object regardless of where the heat originates. To an infrared camera, the cloaked object effectively disappears, while the temperature inside the protected region remains stable.
“A real thermal cloak should work no matter where the heat comes from,” Zhang said in a recent statement. “Our device can hide a complex 3D object in an infinite number of directions while keeping the temperature inside stable and protected.”
As opposed to blocking heat, Zhang and her team’s new cloak redirects it around an object, preserving the temperature field in the surrounding area as though nothing were present.
Although the concept has existed theoretically for many years already, researchers have encountered challenges when it comes to practically leveraging such capabilities.
Redirecting Heat Around Hidden Objects
To overcome past hurdles engineers have faced, Zhang and her team designed a novel lattice-based material, which exhibits thermal properties that allow it to be “tuned” with a great degree of precision in three dimensions.
By combining a 3D-printed aluminum lattice, which serves as a good heat conductor, with a molded rubber-like material that functions as a thermal insulator, the team was able to control the flow of heat through different regions of the device. Additional lab testing helped to confirm its functionality as intended.
Placed between hot and cold environments, the cloak redirected heat around hidden objects, producing an external thermal pattern which they say appeared essentially undisturbed. Simultaneously, temperatures within the cloaked region remained largely uniform, despite the surrounding thermal gradient.
As a further demonstration of its capabilities, the researchers then successfully concealed objects with highly complex three-dimensional geometries, which included detailed head-shaped models that they say surpassed the performance of past versions of thermal cloaks.
Defense and Security Applications
Zhang says the technology could have a wide range of potential applications, especially where precise thermal control is a requirement.
“Any field that needs precise control of heat or needs to protect something from being detected thermally could benefit from this work,” Zhang said in a statement, “But we also see it more broadly: it’s about hiding and protecting information that is carried by heat.”
Additionally, the technology could have applications involving the use of similar cloaks to protect sensitive electronics and microchips from damaging heat, improve thermal management in advanced computing systems, and shield equipment from detection using infrared, which may be useful in security and defense technologies.
Going forward, the team plans on exploring more advanced designs capable of concealing objects that generate their own heat, which could pave the way toward more active thermal cloaks in the coming years that could dynamically manipulate heat and still remain effectively invisible to infrared sensors.
The team detailed their research in a recent paper, “Free-form thermal cloaks in three dimensions,” which appeared in Nature Communications.
Micah Hanks is the Editor-in-Chief and Co-Founder of The Debrief. A longtime reporter on science, defense, and technology with a focus on space and astronomy, he can be reached at micah@thedebrief.org. Follow him on X @MicahHanks, and at micahhanks.com.