Bio-integrated flexible photonics: empowering sensing, therapeutics, and interfacing

Conventional rigid photonic devices are intrinsically limited in their ability to conformally interface with soft, curvilinear, and dynamic biological systems, imposing critical constraints on their biomedical applications. The advent of flexible photonics offers a transformative paradigm to address this challenge through the development of photonic devices constructed from soft, stretchable, and biocompatible materials, enabling seamless bio-integration with catalytic opportunities for biomedical innovations. Here, we present a comprehensive overview of recent advances in bio-integrated flexible photonics, focusing on the materials foundations, structural designs, and fabrication strategies that enable photonic devices engineered to accommodate mechanical deformation while preserving optical fidelity and biological compatibility. We further highlight how these devices empower applications across sensing, therapeutics, and interfacing, and conclude with perspectives on the challenges and future directions of this emerging field.