Some animals, such as chameleons, octopus, or squid, can change their skin coloration for camouflage, temperature preservation, or communication, which has led to scientific efforts to replicate the abilities in artificial skin. However, most developments have shown a visible appearance change only when the artificial skin is subjected to high rates of mechanical deformation. Researchers have now developed electronic skin that has color-changing abilities that can be seen with the human eye without creating excessive strain on the skin. It is the electronic skin’s greater sensitivity to visible color change with less material strain that could lead to improvements in prosthetic devices, wearable devices, and robots. The study was published July 24 in 2D Materials.
The research team used graphene as the highly sensitive strain-sensing element and the insensitive stretchable electrode of the electrochromic device layer. While previous research saw strain of 100 to 500 percent before the color change could be made visible to the human eye, this method found that strain of as little as less than 10 percent was enough to show an obvious color change; the RGB value of the color was used to measure the applied strain.
“Graphene, with its high transparency, rapid carrier transport, flexibility, and large specific surface area, shows application potential for flexible electronics, including stretchable electrodes, supercapacitor, sensors, and optical devices,” Hongwei Zhu, PhD, a professor in the School of Materials Science and Engineering at Tsinghua University, Beijing, China, and the study’s senior author, told IOP Publishing. “However, our results also show that the mechanical property of the substrate was strongly relevant to the performance of the strain sensing materials. This is something that has previously been somewhat overlooked, but that we believe should be closely considered in future studies of the electromechanical behavior of certain functional materials.”