摘要： Visual real-time plasmonic metamaterial biosensors, relying on surface plasmon resonance (SPR) on metallic subwavelength structures, have significant potential for colorimetric biochemical sensing by simple instrumentation or even naked eye. In this paper, we present a visual and real-time sensing strategy for the detection of the biotin-avidin-system (BAS), which is a powerful tool in biological sciences. The metamaterial, consisting of an array of three-dimensional all-metal nano-cavities, can confine the light into the near field and enable strong light-matter interactions there. Therefore, The metamaterial shows significant color shifts with small refraction index changes. When a monomolecular layer of thiolated biotin and streptavidin bonding to the surface of the nanostructure the successively, metamaterials changes from red to violet and then loden. This sensing strategy offers new opportunities for convenient detection of proteins, nucleic acids and lipids.