Chinese researchers have claimed that they have successfully blended myth and science, revealing a pioneering hybrid material that aims to realize the concept of an invisibility cloak. Taking inspiration from the mythical Chimera and incorporating distinct features from three cold-blooded creatures—the chameleon, glass frog, and bearded dragon—researchers, as reported in Chinese media, have made notable advancements in material innovation.

The Hong-Kong-based SCMP first reported on the development of the Chimera metamaterial, which aims to overcome the limitations of existing camouflage technologies by adapting to various terrains and spectral conditions. 

The scientists, from Jilin and Tsinghua Universities, say they have designed an experimental version – based on each animal’s distinct natural survival strategy – that could be undetectable across microwave, visible light, and infrared spectra.

A study published on Tuesday in the peer-reviewed journal Proceedings of the National Academy of Sciences revealed that the researchers adopted a bionics-based approach to address the limitations of existing camouflages, particularly their lack of versatility across different terrains.

“Our work transitions camouflage technologies from the constrained scenario to ever-changing terrains and constitutes a big advance towards new-generation reconfigurable electromagnetics [that can] change circuit topologies,” they said.

The study builds on the swift progress in metamaterials, which are synthetic materials possessing the distinctive capability to manipulate electromagnetic waves. These materials have been increasingly integrated into stealth technologies in recent times.

By meticulously managing their surface structures, metamaterials can manipulate electromagnetic waves to reflect in specific ways, essentially rendering objects invisible to radar. However, their pre-defined functions limit their effectiveness in providing camouflage across diverse environments.

The Chinese scientists envisaged a metamaterial that could adapt to various spectral conditions and terrains while maintaining its resistance to visible and infrared light detection, the paper said.

They named the proposed metamaterial "Chimera," drawing inspiration from the mythical creature composed of three different animals. This choice stems from its incorporation of the chameleon's colour-changing ability, the glass frog's transparency, and the bearded dragon's capacity to regulate its temperature.

Lead author Xu Zhaohua, from Jilin University, said it was “intriguing that suitable working states of the Chimera metasurface can be found to match all the five terrains over the whole frequency range of interest”.

The Chimera’s design was also influenced by the glass frog, found in rainforests throughout Central and South America, which hides most of its blood in the liver during sleep, making the rest of its body transparent.

To achieve a level of optical transparency reminiscent of the glass frog's natural invisibility, the researchers embedded Chimera's circuitry between layers of PET plastic and quartz glass.

The challenge remained of concealing the heat generated by the electricity powering the surface circuits of the metamaterial, which infrared detectors could detect. To tackle this issue, the scientists drew inspiration from Australia's bearded dragon.

These reptiles regulate their body temperature by altering the colour of their backs, shifting from a light yellow when they need to cool down to a dark brown that helps retain warmth.

The Chimera's thermal variations have been reduced to only 3.1 degrees Celsius (5.6 Fahrenheit) by the researchers using a mechanically powered design, making it nearly undetectable to thermal imaging in a variety of terrains.

By mimicking the way bearded dragons respond to their natural environments, the metasurface of the Chimera can reduce to some extent the possibility of its discovery by far-field thermal/temperature detection.

As outlined in the paper, an experimental version of the Chimera metasurface underwent a five-step development process. This process was initiated with a pattern on plastic, followed by the formation of a metal mesh, and concluded with manual assembly, ultimately achieving multi-spectrum stealth capabilities.

The innovation introduced by Chimera holds promising potential for military applications, providing strategic advantages. By enabling seamless integration into various environments, Chimera allows objects or personnel to elude detection by radars, infrared detectors, and optical devices.

This capability has the potential to enhance military operations and maintain a tactical edge in various scenarios.

Despite the ongoing Russia-Ukraine conflict, both sides have claimed significant advancements in the development of camouflage suits designed to counter the thermal imaging equipment employed by their respective adversaries.

On January 24, HiderX, a Russian company, revealed the creation of a new camouflage suit that manipulates the ambient temperature around the wearer. This innovation is intended to make Russian servicemen nearly invisible to thermal imaging devices used by opposing forces. Similarly, Ukraine had made similar claims last year about developing an "invisibility cloak" to shield Ukrainian soldiers from Russian thermal imaging technology.

Image source: Proceedings of the National Academy of Sciences