A range of creatures, including chameleons, octopuses, and frogs, can change colour in response to changes in the environment. Some insights into the mechanisms behind this at the anatomical, cellular, and molecular levels have been obtained. However, much work is still required to obtain sufficient understanding of this phenomenon and to translate it into useful artificial applications.
Researchers at the Department of Molecular Design and Engineering at Nagoya University in Japan developed a material containing dyes and crystals that can change the colours and patterns they display depending on the background colour used within them and their exposure to visible or ultraviolet light.
According to the study, published in the journal Small, the team was inspired to develop this material by findings obtained in the skin of certain frogs, in which different layers of cells with different properties combine to enable remarkable colour changes.
Each component of this novel material plays a key role in its colour properties. For example, the dyes contribute their inherent colours to the material’s appearance, which can be adjusted by mixing them to different extents. These dyes also include those that change colour upon exposure to light.
Spherical crystals were also introduced into the system, which, rather than influencing the colour through their inherent pigmentation, affect it through their microscopic structures that can directly interfere with light. Finally, a black pigment and different background colours were employed to alter the colours the other components of the system display, as reported in the study.
“We examined the influences of the different components in the system, such as by changing the size of the crystals, switching the background from white to black, or performing exposure to visible or ultraviolet light,” said the corresponding author of the study, Yukikazu Takeoka. He added, “we found these changes resulted in different colours being displayed across the material, resembling the way in which some organisms can change colour in response to various factors in their environment.”
“This is an exciting stage in this field of study, as we are increasingly able to adapt the colour-changing mechanisms that some animals use to artificial devices,” the study’s lead author Miki Sakai explained. “If these artificial colour-changing materials can equal or surpass the vibrant displays that some animals such as octopuses and frogs make, it could have exciting applications in the development of new display technologies,” he added.