Fiber-optic fluorescence reader for multiplex point-of-care monitoring.

We present a compact fiber-optic fluorescence reader for quantitative, multiplex point-of-care (PoC) analysis of lateral flow assays (LFAs). The system uses a dual-port fiber Bragg grating (FBG) spectrometer for spectral discrimination and interchangeable excitation sources covering 400-800 nm to support multiple fluorophores. As a proof of principle, we quantified piperacillin in human serum with an europium nanoparticle-based competitive LFA, achieving a limit of detection (LOD) of 12.9 mg/L and a dynamic range of 10-500 mg/L. The reader-LFA system showed strong agreement with a laboratory reference method (Pearson's r = 0.95) and a mean absolute error of 22.9 mg/L across ten patient samples. In addition, we demonstrate multiplex detection of opiate and cocaine markers using distinct fluorophores on a single test line. These results support the feasibility of portable, spectrally resolved PoC diagnostics for therapeutic drug monitoring and multiplex biomarker detection in clinical and low-resource settings.