Colorimetric metasurfaces shed light on fibrous biological tissue

Fiber-affecting diseases – encompassing fibrosis, heart disease, neurological disease and cancer – are directly linked to the density and reorganization of fibrous media in biological tissue. Polarized light has unique capabilities to probe the structural reorganization of fibrous biological media, yet naturally occurring anisotropic light–matter interactions lie below thresholds relevant for disease visualization. Nano-optical metasurfaces have demonstrated immense capabilities to enhance light–matter interactions. However, beyond the initial focus of the field on energetic enhancement, the study of nano-optical materials which selectively enhance anisotropic light–matter interactions is at its infancy. This perspective highlights how colorimetric metasurfaces, with abilities to quantitatively map the polarization state of light onto structural color, hold great potential to visualize disease in fibrous biological tissue. We first discuss a range of major fiber-affecting diseases, where the role of tissue microstructure in disease progression has been characterized with polarized light, with a focus on Mueller Matrix polarimetry. Subsequently, an overview of state-of-the-art polarization-sensitive colorimetric metasurfaces in plasmonic, dielectric, hybrid and tunable platforms is presented. The insights provided forge a path to bridge the fields of tissue polarimetry and colorimetric metasurfaces for miniaturized, all-optical and label-free disease visualization enabled by the nanoscale science of light.