Illinois Researchers 3D-Print a Thermal Cloak That Hides Objects From Infrared Cameras

A team from the University of Illinois Urbana-Champaign and the Technical University of Denmark has built the first omnidirectional 3D thermal cloak using metal additive manufacturing. The device guides heat around a hidden object so smoothly that an infrared camera sees almost no temperature disturbance.

Previous thermal cloaks worked as flat plates or handled heat from only one direction. This version adapts to irregular 3D shapes and changing heat flows. The researchers map how heat should travel around the protected object, then translate that path into a lattice structure whose density and orientation shift from one region to another.

The cloak combines a 3D-printed aluminum lattice with PDMS, a rubber-like material that blocks heat flow. The aluminum creates carefully positioned channels through the structure, while the PDMS slows heat down elsewhere. By varying the thickness and direction of the lattice bars, the team controls exactly where thermal energy travels.

For testing, the team placed an apple-shaped core inside a pear-shaped shell and sandwiched the structure between two aluminum plates. One side reached 40 degrees Celsius, the other used iced water. After an hour, infrared images showed heat flowing around the inner object and resuming its original pattern on the other side. The apple stayed thermally invisible.

The researchers also tested face-shaped prototypes generated from digital surface data. Simulations confirmed those versions could hide objects from heat arriving along three different axes at once.

Practical uses remain distant. The current cloak is rigid, shape-specific, and works only in controlled lab settings. It cannot yet hide objects that generate their own heat. The next research phase will explore active systems that manage internal warmth, bringing thermal invisibility closer to real-world deployment.