Scientists have developed a synthetic skin capable of mimicking some of the best camouflage skills in nature that could also have applications in soft robotics and advanced displays.
The team from Stanford University created a thin film that can be programmed to alter its apparent texture and color, a feat previously only available within the animal kingdom.
The technique employs electron beams to write patterns and add optical layers that create color effects. When exposed to water, the film swells to reveal texture and colors independently, depending on which side of the material is exposed, according to a paper published in the scientific journal Nature this week.
In an accompanying article, University of Stuttgart’s Benjamin Renz and Na Liu said the researchers’ “most striking achievement was a photonic skin in which color and texture could be independently controlled, mirroring the separate regulation… in octopuses.”
The research team used the polymer PEDOT:PSS, which can swell in water, as the basis for their material. Its reaction to water can be controlled by irradiating it with electrons, creating textures and patterns in the film.
By adding thin layers of gold, the researchers turned surface texture into tunable optical effects. A single layer could be used to scatter light, giving the shiny metal a matte, textured appearance. To control color, a polymer film was sandwiched between two layers of gold, forming an optical cavity, which selectively reflects light.
“This concept could be extended to soft robots or adaptive architectural facades that modulate their reflectivity in response to environmental stimuli. By designing how matter interacts with light, scientists are beginning to imbue materials with the ability to disguise, reveal and perform – much like the living organisms that continue to inspire us,” Renz and Liu said.
“This platform enables functional surfaces for applications ranging from dynamic camouflage and display for soft machines to new types of photonic devices,” said a paper announcing this discovery from materials science professor Mark Brongersma and his team. ®