Investigation of the origin of structural colors in calliphoridae flies for bioinspiration

The article presents a study of the origin of iridescent structural coloration in the thorax of the Calliphoridae fly, intending to inspire in this fly optical and structural properties of interest for use in industry. We carried out SEM microscopic analyses and modeled optical properties using the transfer matrix. The results indicate that this coloration is due to the presence of a one-dimensional photonic crystal composed of two alternating layers of specific thickness. Microscopic analysis using a scanning electron microscope led to this conclusion. Based on these results, a model was proposed describing the structure as consisting of chitin and air. By modulating the optical properties of this structure at different angles of incidence, it was observed that the iridescent colors, notably green, blue, and violet, matched the predictions made by this modulation. These colors are the result of constructive interference. In addition, we observed the presence of a photonic band gap when exploring the influence of the periodicity of chitin and air multilayer in the fly on reflection intensity. Thus, a comparative study of the fly and that emerged in water with a different refractive index revealed consistency in our model. Finally, the results obtained improve our understanding of the mechanisms responsible for this coloration and pave the way for the development of new materials inspired by nature, with potential applications in the fields of biomimetic engineering and optics.