Metasurface biosensors: Status and prospects

Metasurfaces have emerged as a rapidly evolving frontier in the fields of optics and photonics, with a growing emphasis on their potential for practical applications. The considerable volume of contributions to the study on metasurfaces has expanded, creating challenges in tracking all the advancements within this dynamic field. In this review, we select practically useful metasurfaces among the diverse metasurfaces studied so far. We refer to the selected hot research topics in metasurfaces at the beginning, succeedingly outline the status of several applications that are nearing practical applications, and then focus on biosensing applications, with particular attention to metasurface fluorescence (FL) biosensors, because FL detection is a major approach in bioscience and biotechnology. However, the contributions to FL detection by metasurface biosensors have not been reviewed in an extensive and comprehensive manner. Indeed, the metasurface FL biosensors have demonstrated capability of detecting a wide range of biomolecules including nucleic acids and proteins, such as antigens and antibodies. Notably, they offer enhanced sensitivity assays and reduced assay time when compared to conventional commercial assays. We here provide a focused review on the current status and future directions of metasurface biosensors.