Bio-inspired photonics
The Greek philosopher Anaximander, widely regarded as the first scientist, had a student named Anaximenes, who had the first documented mention of bioluminescence.
It was not until the early microscopes, utilized by Robert Hooke in the mid-1600s,[13] that allowed humans to observe nature in greater detail.
[14] Here he describes various biological structures such as the feathers of colorful birds, wing and eyes of flies, and pearlescent scales of silverfish.
This ability to look at the microstructures of nature, gave scientists information on the mechanisms behind the interactions between biology and light.
The Theorie of Imperfection, published by the Russian biophysicist Zhuralev and American biochemist Seliger, is the first working hypothesis about the ultra-weak emission of photons by biological systems.
Molecular biomimetics involves the design of optical materials based on specific molecules and/or macromolecules to induce coloration.
[20] Pigment-inspired materials aiming for specific molecular light absorption have been developed as for example melanin-inspired films prepared by polymerization of melanin precursors such as dopamine and 5,6-dihydroxyindole to provoke color saturation.
[20] Materials based on the multi-layer stacking of guanine molecular crystals found in living organisms (e.g. fish[25] and chameleons[26]) have been proposed as potential reflective coatings and solar reflectors.
[35][36] Pressure and solvent polarity affect the color of a manufactured cellulose membrane, to the point of detection by the naked eye.
When the melanin rods are parallel to the lattice arrangement of the structure of the keratin outer layer it creates the brown color.
[20][47][48][49] Aperiodic Photonic Structures do not have a unit cell and are capable of creating band gaps without the requirement of a high index of refraction difference.
[59] The mechanisms behind these tactics are called chromatophores, which are pigment-filled sacs that uses muscles and nerves to change the animal's external appearance.
The animal can use these opsins to their advantage to quickly assess their surroundings, before turning on their chromatophores to accurately camouflage to their circumstances.
Counterillumination, a tactic used more by deep-sea dwellers, uses a luminous organ located in the bottom of the body to emit light in order to appear brighter from underneath.
Within the luminous organ is a laminar structure of photocytes and nerve branches, with relatively small gap junctions between them.
[62] It is thought that the vast interconnectivity and the layered structure of these neuro-photocyte units is what allows a deep-sea fish to rapidly respond to a situation with spontaneous luminescence.
Because all of the nerves are directly connected to the spinal cord (and by extension, the brain), researchers believe that electronic signals can trigger these photocytes to react.
[64] This technology can be used to camouflage objects, create a device that can mold its shape yet still retain its desired properties, or even help people in relation to biomedical applications.
