Photonic crystal microspheres: Synthesis, characterization, and applications in colored contact lenses

Structural colors arise from the interaction between light and ordered structural materials, making them the ideal choice for colored contact lenses. This study utilized a fast, large-scale synthesis method for silica photonic crystal microspheres, introducing carbon black to enhance the structural coloring effect. The sintering process strengthened the cohesion between particles, increasing their strength and expanding their range of applications. This approach successfully prepared SiO2 photonic crystal inks with structural colors to produce contact lenses through a pad printing technique. In particular, the coloration is solely achieved using SiO2 and carbon black without other organic species. The resulting structural color blue contact lenses exhibit high light transmittance and vivid structural colors. Furthermore, the following necessary properties were me: oxygen transmittance, visible light transmittance, hydrophilicity, and lipid and protein adsorption of the contact lenses. Cell viability experiments indicate that contact lenses made from this material are biocompatible. The results illustrated that these as-prepared lenses are promising candidates for traditional colored contact lenses.