The chameleon, a remarkable lizard known for its color-changing skin, has long intrigued scientists. Its ability to seamlessly blend into its surroundings is not just a captivating visual phenomenon; it offers deep biological insights. Now, this adaptive trait has inspired cutting-edge innovations in materials science, most notably in the creation of an electromagnetic material that could revolutionize technologies across various fields, such as defense, communications, and energy harvesting. As detailed in a groundbreaking study published in Science Advances, researchers from the University of California, Berkeley, have designed a tunable metamaterial microwave absorber, capable of switching between absorbing, transmitting, or reflecting electromagnetic waves with the same dynamic flexibility that allows a chameleon to adjust its skin tone.
Tuning Materials to Control Electromagnetic Waves
At the heart of this breakthrough is a novel microwave absorber that mimics the adaptive properties of the chameleon’s skin. This flexible material can be tuned in real-time to interact with microwaves, ranging from radar to communication signals, in different ways. The primary achievement here, as explained by Grace Gu, the principal investigator of the study and an assistant professor of mechanical engineering, lies in combining both broadband absorption and high transmission in a single, dynamically adaptive structure. In practical terms, this could transform systems that currently rely on static materials with fixed electromagnetic responses, creating the possibility for materials that react to ever-changing environmental conditions.
For years, researchers have faced a challenge in creating materials that can efficiently absorb electromagnetic waves, such as microwaves or radar signals, while remaining responsive to dynamic environments. As Gu explains, traditional materials in this domain tend to work with a “one-size-fits-all” approach. Once they are manufactured, their behavior is fixed, unable to adapt based on changes in the surrounding environment. To overcome this limitation, Gu and her team sought inspiration from the chameleon—which adjusts its skin’s light reflection by changing the spacing between photonic crystals, altering how light is absorbed or reflected.
This fundamental understanding of chameleon-like adaptability laid the foundation for their metamaterial design, aiming to control electromagnetic waves similarly by altering its physical configuration.
Creating the Tunable Metamaterial
The researchers turned to mechanical metamaterials, which derive their unique properties not from the material composition, but from the structure itself. Specifically, the team designed a crisscross truss structure that can physically change shape by collapsing or expanding. These adjustments—engineered through an interlinked network of trusses—allow the material to change its electromagnetic response from one of broad absorption (rendering objects invisible to radar) to one of transmission (allowing communication signals to pass through). This transformative design made possible a mechanism that can adapt to different needs, a feat reminiscent of a chameleon’s ability to adjust color for camouflage or signaling purposes.
The physical properties of the material change in real-time, controlled by the morphing truss structure. The innovation here lies in the precision of its transformations. Machine learning and genetic algorithms were used to optimize the structure’s design, allowing researchers to program specific, targeted electromagnetic responses. Once optimized, the structure was fabricated using 3D printing techniques, which permitted quick iterations and testing, facilitating efficient prototyping.
In practice, the material achieves a near-invisibility effect. As reported by the study’s first author, Daniel Lim, a postdoctoral researcher, when the material is in its collapsed state, it can absorb over 90% of microwaves in the 4–18 GHz frequency range. In essence, the material absorbs radar waves, rendering it virtually invisible to detection—a crucial step for applications in stealth technology. However, when the structure is expanded, it can transmit as much as 24.2% of signal strength, allowing for communication or data transmission when required.
Real-World Applications and Benefits
The potential impact of this bioinspired electromagnetic material is vast. Defense technologies, in particular, stand to benefit greatly. Vehicles and aircraft designed with this tunable metamaterial could seamlessly switch between stealth (making them undetectable to radar) and communication modes (allowing for active transmission of signals when required). Such capabilities would significantly enhance the versatility and operational flexibility of military systems. Similarly, vehicles could potentially go undetected when they need to be invisible but allow essential communications to continue without interference.
Moreover, the applications extend beyond military uses. The same technology could be used to create smart windows that can alternate between blocking and transmitting signals, enhancing privacy and communication security. This could benefit sectors such as telecommunications, where data confidentiality and control over information flow are paramount. The material also has a promising future in the realm of energy harvesting, particularly in systems designed to capture and convert electromagnetic waves into energy for powering sensors, batteries, and other devices.
Gu, alongside her team, also envisions the metamaterial playing a crucial role in the future of smart infrastructure, where adaptive materials could be used to optimize energy consumption, improve communication systems, and contribute to the broader adoption of sustainable technologies. By harnessing the power of real-time adaptability, the material could meet ever-changing demands across these and other domains.
Future Potential and Advancements
Looking forward, there is great optimism surrounding the future applications of this technology, particularly as it begins to take its place in the broader landscape of metamaterial engineering. Metamaterials, often constructed in highly engineered patterns at microscopic scales, have already exhibited remarkable properties in a range of fields, from soundproofing to light manipulation. The unique capacity of Gu and her team’s design to change electromagnetic wave behaviors on-demand gives this project significant versatility, opening doors to countless new applications.
In the future, scientists are hopeful that the tunable nature of this material could lead to breakthroughs in adaptive camouflage—for military, as well as civilian uses. Whether providing the military with low-radar profiles in combat or allowing driverless vehicles to remain undetectable to nearby traffic sensors, this metamaterial could be central to future electromagnetic wave management solutions.
Additionally, the scalability of 3D printing also ensures that the manufacturing of this material could be achieved efficiently, making it an adaptable and cost-effective option for widespread commercial use. Its ability to achieve specific microwave absorption and transmission properties presents exciting possibilities for next-generation communication and security systems.
Conclusion: From the Chameleon to Cutting-Edge Technologies
The development of this chameleon-inspired electromagnetic material marks a significant leap forward in materials science. By mimicking the reptile’s ability to shift and adapt its response to its environment, UC Berkeley’s researchers have created a versatile tool capable of managing electromagnetic waves with unprecedented efficiency and flexibility. This innovation combines the creativity of biological systems with modern engineering, enabling practical, real-time applications that span several industries, from defense technology to smart infrastructure and communications.
Thanks to this development, we are one step closer to creating intelligent systems that are not only more adaptive to their environments but also capable of meeting dynamic technological demands as they arise—just like the color-changing chameleon. Whether it’s for stealth, secure communication, or efficient energy harvesting, this metamaterial represents the future of electromagnetic technology—one in which adaptability and flexibility become crucial components of the technological landscape.
Reference: Dahyun D. Lim et al, A tunable metamaterial microwave absorber inspired by chameleon’s color-changing mechanism, Science Advances (2025). DOI: 10.1126/sciadv.ads3499