Fig. 6
From: Melanin-based structural coloration of birds and its biomimetic applications
PDA-based artificial melanin for producing structural colors. (a) Structural colors using a PDA coating on a silicon wafer. (Scale bar: 1 cm). Reproduced with permission (Zhang et al. 2017). Copyright 2017, Royal Society of Chemistry. (b) Structural colors by thin-film interference of PDA nanoparticles. (Scale bar: 500 nm). Reproduced with permission (Xiao et al. 2015). Copyright 2015, American Chemical Society. (c) Supraball-type photonic ink from a PDA core and silica shell nanoparticles. (Scale bar: 500 nm). Reproduced under the terms of CC BY license (Xiao et al. 2017). Copyright 2017, The Authors. Published by The American Association for the Advancement of Science. (d) Nanoparticles’ aspect ratio dependent structural coloration. Reproduced with permission (Kohri et al. 2019). Copyright 2019, American Chemical Society