INTELLECTUAL MERIT: In the colored structures of many insects, colors are generated by optical interference produced through the interaction of light with periodically ordered low and high refractive index structures incorporated into the exoskeleton of the insects. Such structural colors have recently been of interest for use as photonic crystals with potential impact in next-generation energy and information technology applications. While current photonic engineering capabilities at visible wavelengths are rather limited, biological systems have evolved to create the most complex photonic architectures structures that are still far out of our synthetic reach. The proposed research is directed towards these biostructures and is focused on gaining detailed insights into the photonic structure formation/assembly mechanism of biological systems and developing biomimetic routes for the fabrication of novel three-dimensionally ordered dielectric materials for photonic applications. The PI will conduct high-resolution structural investigations of photonic architectures in iridescent beetles to uncover both the exact crystal lattices and their assembly environment. From these results, he will develop biomimetic structure formation experiments to study the assembly chemistry and physics of biopolymeric compounds in terms of solution composition, presence of surfactant-type molecules, and assembly/phase separation mechanism (nucleation and growth vs. spinodal decomposition). He will also combine these biopolymeric formation studies with spatial confinement effects. The goal is to mimic the three-dimensionally confined assembly-chambers in many beetles (exoskeleton scales) by fabricating microcompartments and investigating biopolymer structure assembly in these confined spaces. From these studies it is hoped not only to gain valuable insights into the fascinating variation of structural colors in biology but also to develop novel synthesis approaches for complex bioinspired photonic materials for advanced optical and optoelectronic applications.
BROADER IMPACTS: A central mission of the proposed activities is the integration of research and educational efforts at several levels. In collaboration with a local high school, integration will be pursued through an "adopt-a-class" approach, where we will involve and guide students in science projects related to nanomaterials, light and energy. This will be accomplished through mutual visits several times a year and an email/internet "science hotline." It is anticipated that the discoveries and results from these projects will be publicly displayed at the Utah Science Day and in the form of a temporary installation at the Utah Museum of Natural History. At the undergraduate level, integration will be achieved through the installment of a "special" experiment (in addition to typical "designed" teaching experiments) in the PI's undergraduate lab course, where for several days students will perform "real world" research side-by-side with the PI's graduate students. At the graduate level the new students selected will be specifically trained in the interdisciplinary aspects of this proposal, including training on the PI?s optical spectroscopy lab facility and on other campus facilities (TEM, SEM, AFM, etc.). Special efforts will be focused on the recruitment and involvement of minority and female trainees. In addition, the proposed research will gain new insights into biological structure formation and thus has enormous potential in photonic materials engineering via novel biomimetic fabrication routes. Photonic structures promise breakthroughs in energy and information technology and therefore promise to deeply impact our society in everyday life.
Biological systems have been an infinite reservoir of inspiration ever since humans started to develop tools and machinery. Just as early scientists and engineers attempted to mimic birds and fish in the development of flying machines and submarines, today, new technologies find their inspiration from biology, such as gecko feet, anti-reflective eye lenses, iridescent insects, and water-repellant surfaces. Incorporating biological systems and concepts into technological design can happen in several ways: inspiration, mimicking, and replication. Research of this project focused on all three of these aspects. In particular, we studied iridescent colored beetles and extracted the nanostructures behind their iridescent appearance. From these studies we developed bioinspired and biomimetic fabrication routes to create similar structures but made out of technologically-relevant compounds, semiconductors and photocatalysts. In the course of this project we developed Bragg stack photonics made out of various oxides, photonic crystals with incorporated light sources, and lipid-based nanostructures. We showed these structures to strongly interact with light and to be useful in light amplification and guiding. Outcomes of our studies are anticipated to be of use in photocatalysis, light amplification, and as solar spectrum splitters. This research project had a strong and positive impact on the development of human resources. Students at various levels (high-school, undergraduate, and graduate) were involved in this project and trained in state-of-the-art chemistry, fabrication and characterization methods. All students were also trained in scientific writing and communicating with the goal to becoming excellent science ambassadors. We also provided outreach to the general public through seminar presentations at local museums, participation in science fairs, and non-typical science events (e.g., PechaKucha event).
