Breaking free from spectral limits
From thermal cameras to multispectral sensors, modern surveillance technologies are increasingly difficult to evade, creating urgent demand for camouflage that adapts across both visible and infrared bands. Yet progress has long been constrained by three persistent challenges: the tight coupling between visible color shifts and infrared emissivity, which forces trade-offs; the limited thermal modulation range of existing devices, typically <15 °C and insufficient for extreme environments such as deserts with >60 °C swings; and scalability constraints, with most prototypes restricted to small laboratory samples.
Now, researchers at Zhejiang University and Westlake University have overcome these barriers with a multilayer device that decouples visible and infrared control, achieves record-wide thermal modulation, and scales to programmable multipixel arrays. The breakthrough is reported in PhotoniX.
A layered solution for extreme environments
The team's multilayer design integrates three functional components in a compact stack: a thermochromic layer that switches from green to yellow at 28 °C, blending seamlessly into both oasis vegetation and desert sand; a carbon nanotube–based electrochromic layer that adjusts infrared emissivity from 0.44 to 0.84 across the 8–14 μm band; and a thermoelectric module that controls surface temperature between 10 °C and 60 °C. Working together, these layers deliver an unprecedented 67.7 °C span of radiative temperature modulation—several times greater than previous technologies—allowing objects to appear green and cool in desert nights, yellow and warm under daytime heat, or naturally matched to lush oases.
Decoupling visible and infrared responses
A key advance of the new design is its decoupled visible and infrared responses. In most existing materials, changes in visible color are accompanied by changes in infrared signatures, limiting effectiveness. By introducing a thermochromic layer with high infrared transparency, the researchers overcame this constraint. As a result, visible colors can shift independently of emissivity, allowing the device to match its surroundings more accurately in both spectral ranges.
From laboratory pixels to scalable devices
Moving beyond proof-of-concept, the researchers fabricated a 13 × 13 cm² multipixel prototype. The device displays camouflage patterns in the visible spectrum while dynamically generating programmable infrared patterns such as letters "F" and "H." The ability to address each pixel independently suggests potential for large-area, scalable camouflage and encrypted information displays.
Applications beyond camouflage
While the immediate applications lie in defense and stealth, the platform's broader implications are equally compelling. The principles of decoupled visible/infrared control could inspire energy-efficient smart windows with independent solar reflectance and radiative cooling, reconfigurable optical systems for hyperspectral calibration, and wearable photonics for personal thermal management.
