Illinois Engineers Build a 3D-Printed Thermal Cloak That Hides Objects From Heat

University of Illinois Urbana-Champaign engineers have built the first 3D device that can hide objects from heat in every direction. The thermal cloak uses a 3D-printed aluminum lattice filled with a rubber-like material to guide heat around a hidden region, making that region appear invisible to infrared cameras.

Previous thermal cloaks worked only in two dimensions or from a single direction. Heat approaching from another angle would reveal the hidden object. The Illinois team solved that problem by designing a lattice structure with conductances tuned independently in three directions. The result is a cloak that works no matter where the heat comes from.

"A real thermal cloak should work no matter where the heat comes from," said Shelly Zhang, a civil and environmental engineering professor at Illinois. "Our device can hide a complex 3D object in an infinite number of directions while keeping the temperature inside stable and protected."

The team fabricated the device by 3D printing an aluminum lattice using direct metal laser sintering, then filling the lattice with a low-conductivity rubber through mold casting. The lattice geometry can be adjusted to create exactly the right mix of high and low conductivity regions for any given shape. The researchers tested the cloak with simple geometric shapes and with a human face, both of which remained hidden from thermal detection.

In the lab, the researchers placed the cloak between a 40-degree Celsius heat source and an iced-water cold source. Infrared cameras showed heat flowing smoothly around the protected region and rejoining on the other side. Inside the cloak, the temperature stayed uniform and isolated from the external extremes.

The study, published in Nature Communications, demonstrates that the lattice design can be scaled to almost any shape. Potential applications include protecting sensitive electronics from thermal imaging, managing heat in microchips, and shielding equipment from infrared detection. The same approach could eventually be adapted for electrical conduction and pressure flow, turning a thermal cloaking trick into a general platform for controlling how energy moves through materials.