Sözmen, A.B.Bayraktar, A.E.Ülker, Ö.Arslan-Yildiz, A.2025-08-272025-08-2720250065-2423https://doi.org/10.1016/bs.acc.2025.07.001https://hdl.handle.net/11147/18386A sensor detects changes in its environment and converts them into readable data using three key components: a receptor to sense changes, a transducer to generate a signal, and a detection system to output the signal. Optical sensors are devices that use a receptor and optical transducer to produce signals corresponding to an analyte, and optical biosensors combine a biological sensing element with an optical transducer to detect and quantify specific analytes. They offer easy-to-read, real-time signals, such as color changes or light emission, sometimes even detectable by the naked eye, reducing the need for external devices and providing versatile Point-of-Care (PoC) applicability. Their portability and rapid response time enable remote testing and monitoring, further improving accessibility. They allow sensitive and selective detection of various analytes, making them utile in areas like glucose monitoring, drug testing, and pathogen detection. Many of these sensors provide label-free and non-invasive detection, further enhancing patient comfort and safety. This chapter provides an overview of optical biosensors; it starts with categorizing them by biorecognition elements, transducers, and detection modes. It investigates biosensors that utilize nanomaterials, polymers, and engineered biorecognition elements are discussed, with examples from literature. Technologies such as miniaturization, multiplexing, and wearable designs, which enhance PoC feasibility, are also examined. Lastly, challenges in development and operation are addressed, and future research directions for advancing optical biosensors in PoC diagnostics are discussed. © 2025eninfo:eu-repo/semantics/closedAccessAdvanced Materials In BiosensingBiorecognition ElementsClinical DiagnosticsOptical BiosensorsOptical TransducersPoint-Of-Care DiagnosticsArticle2-s2.0-10501162173810.1016/bs.acc.2025.07.001