Skin is not merely an outer covering that separates a living organism from its environment; it is a dynamic, active interface that constantly interacts with the world around it. It captures light, responds to touch, and transmits subtle signals of safety or danger. This role culminates in the skin of the octopus, which possesses an astonishing ability to change its color and texture in moments, adapting to its surroundings in a behavior akin to the art of natural optical illusion.
This biological marvel has not only fascinated scientists but has also prompted them to ask: Can these advanced properties be transferred to synthetic materials, transforming the surfaces around us from inanimate and silent elements into interactive entities capable of responding to their environment?
A Synthetic Material Inspired by Octopus Skin
In this context, Nicholas Miloch, a professor at Stanford University specializing in bio-inspired soft materials, and his research team are working on developing a synthetic material that combines color and texture changes within a single system, mimicking the behavior of octopus skin with remarkable accuracy.
In an exclusive interview with LMA, Miloch explains that the essence of this achievement lies in the material's internal structure. To interact with light and produce multiple colors, the material requires controlling the size and shape of its components at a micron-scale level—much smaller than the thickness of a human hair. The challenge is further complicated by the material's soft, jelly-like consistency, allowing it to expand and contract, and thus constantly change its dimensions.
To overcome this hurdle, the team employed techniques inspired by semiconductor manufacturing, enabling the material to be selectively and precisely shaped. This results in the creation of microstructures capable of reflecting different colors of light while simultaneously imparting a variable texture to their surface.
Siddharth Doshi, a research fellow at Stanford University specializing in responsive materials and human-technology interfaces, explains that previous attempts encountered a fundamental obstacle: the inherent link between color and texture. When one changes, the other inevitably follows suit. He adds that previous materials relied on controlling the interference of light waves within micro- and nano-scale structures, making independent control of properties virtually impossible.
However, the research team succeeded, for the first time, in separating color control from texture control, allowing for individual adjustments to each property and opening new horizons for more precise and complex applications.
From Hospitals to Robotics
Regarding the potential benefits of these "smart skins," Milos points out that our relationship with objects is not solely based on their function, but is significantly influenced by their appearance and texture. A device or robot might appear dangerous or unreliable simply because of its rough surface or harsh appearance, while a smooth, refined surface conveys a sense of security and quality.
He emphasizes that controlling surface textures could be of great value in healthcare environments, where surfaces can be designed to be more resistant to bacteria or less prone to liquids, thus limiting the transmission of infections.
He also notes that many modern robots, whether large ones designed for direct human interaction or small ones capable of performing precise tasks, are increasingly drawing inspiration from animal designs, making the integration of interactive skins a logical step in their future development.
Skin as a Means of Communication
Siddharth Doshi argues that the inspiration drawn from cephalopod skin extends beyond camouflage to include communication and signaling. These creatures use their skin as a language of expression, not merely a protective covering. This opens the door to developing artificial skins that enable robots to communicate with humans through changes in color or texture, rather than relying solely on screens or sounds.
Potential Military Dimensions
However, the same properties that make these skins safer and more flexible for civilian use could have practical applications in more sensitive areas, such as military applications. The ability to change appearance or texture could be leveraged to camouflage equipment and small robots operating in complex environments, or to reduce friction and noise during movement.
Furthermore, surfaces capable of transmitting information through touch or visual change could provide silent communication methods in operational environments that do not allow for the use of sound or light. While these scenarios remain theoretical, they illustrate how nature-inspired technologies can transcend the limitations of traditional applications.
Challenges and Future Prospects
Despite the vast potential, Milos warns that these technologies still face a fundamental challenge: material durability. Repeated use can lead to wear and tear, negatively impacting performance.
In contrast, Doshi envisions even greater possibilities, including reimagining human-machine interfaces beyond mere touch. He envisions developing screens capable of mimicking realistic textures and colors, opening up new avenues for communication, design, and even artistic expression.
