EAGER: Bio-Inspired Active Structural Color

University Of North Carolina At Chapel Hill, Chapel Hill NC

Investigators

Abstract

Non-technical Description: Current computer displays and televisions are windows that offer a limited simulation of the real world. There is a need to develop a distinct technology capable of creating real physical manifestations of computer-created virtual objects that can be seen and touch as real things. Nature masterpieces such as the cuttlefish's color and texture changing abilities prove that such technology is possible, and it is up to us to learn from nature's blueprints. The goal of this project is to develop the foundation for a technology capable of replicating the elegant color mechanism of tropical butterflies but be able to tune it from red to blue using materials that work as artificial muscles following the cuttlefish lessons. Because this muscle material is based on intrinsically soft components, it could reproduce color and texture toward the overall integration of visual and tactile experience in, for example, a truly artificial chameleonic skin. In addition to research, the project promotes the development of the future science and engineering work force by training graduate and undergraduate students to think and work at the interdisciplinary boundary between science and engineering. In collaboration with Morehead Planetarium at University of North Carolina, education presentations and activities are carried out to enhance K-12 students', teachers', and the general public's understanding of natural and artificial color phenomena. Technical Description: This research project addresses two crucial materials challenges to the realization of a controllable and flexible structural coloration scheme using electric-field actuated elastomers: First, a tunable photonic crystal structure with near zero angular color dependence should be created on a soft-flexible dielectric elastomers with a scalable method capable of patterning large surface areas. Second, the visible-wavelength size features of such photonic structure require the elastomers to be operated on length scales smaller than its currently proven range. The activity addresses these issues by correlating materials properties (dielectric strength, elastic modulus) to the photonic crystal dimensions under electric fields and to the optical changes that result from this actuation. The relative merits of different dielectric elastomers and photonic structure replication methods at the required lengths scales are assessed, and the photonic crystal structures are characterized by comprehensive electron microscopy, diffuse and angular light reflection measurements, and perceptual color evaluation.