Structural colour printing using a magnetically tunable and lithographically fixable photonic crystal

Many creatures in nature, such as butterflies and peacocks, display unique brilliant colours, known as 'structural colours', which result from the interaction of light with periodic nanostructures on their surfaces. Mimicking such nanostructures found in nature, however, requires state-of-the-art nanofabrication techniques that are slow, expensive and not scalable. Herein, we demonstrate high-resolution patterning of multiple structural colours within seconds, based on successive tuning and fixing of colour using a single material along with a maskless lithography system. We have invented a material called 'M-Ink', the colour of which is tunable by magnetically changing the periodicity of the nanostructure and fixable by photochemically immobilizing those structures in a polymer network. We also demonstrate a flexible photonic crystal for the realization of structural colour printing. The simple, controllable and scalable structural colour printing scheme presented may have a significant impact on colour production for general consumer goods.