32—The Colors of the Unicorn
Adrian Rodriguez-Palomo, Chalmers University of Technology
Narwhals are unique animals that have fascinated humans for centuries due to their "unicorn-like" spiralled tusk. The origin and function of this tusk is still a mystery; however, like other biological materials, narwhal tusk has an impressive three-dimensional hierarchical structure from the nano to the macro scale. In this image, the cross-section of a narwhal tusk was measured using birefringence microscopy. The different orientations of the collagen fibrils in the tusk interact with polarised light, changing its polarisation angle and phase, which is later measured by the microscope camera. This information is then processed in an image where poorly oriented collagen appears in grey tones. On the other hand, highly ordered collagen show bright colours corresponding to the different in-plane orientations, as in this rainbow-like pattern. No artificial post-processing colouring has been applied for aesthetic purposes. These bio mineralised tissues are advanced composite materials created by nature with impressive properties that emerge through complex hierarchical structures. The study of such natural structures is a source of inspiration for scientists and engineers to create new bio-inspired materials with enhanced properties and new functionalities in fields like medicine, architecture, energy storage, catalysis and more. Author: Adrian Rodriguez-Palomo. Co-authors: Marianne Liebi, Jonas Palle, Nina Kølln Wittig, Henrik Birkedal, Eva Garde, Mads Peter Heide Jørgensen.