Biomimetic illumination enhancement inspired by guanine platelets in the photophore surface of the deep-sea bristlemouth Sigmops gracilis.

Abstract

Efficient illumination and light management are increasingly important in modern society. Biomimetic strategies inspired by biological optical systems have, therefore, attracted considerable attention for the development of novel photonic devices. This study investigates light control mechanisms in the photophores of the bioluminescent deep-sea bristlemouth Sigmops gracilis (Gonostomatidae). The reflection and scattering properties of photophores were examined under external illumination. Strong light scattering from guanine platelets was observed on the photophore surface. The observed scattering behavior was successfully reproduced using a biomimetic model consisting of multiple aligned thin chambers containing guanine platelets suspended in water, demonstrating that multilayered platelet assemblies significantly enhance reflectivity. These results indicate that the accumulation of guanine platelets at the photophore surface contributes to increased light intensity around the photophore. In addition, guanine platelets exhibiting anisotropic directional scattering, similar to that observed on the fish body surface, were reconstructed using a magnetic rotation method. Together with previous findings on internal photophore components, these results suggest that external photophore structures in bioluminescent deep-sea fish provide an effective biomimetic strategy for the efficient reuse and redirection of light emitted from photocytes.