How is spectroscopy used for real-time bioprocess monitoring?

Spectroscopic techniques enable non-invasive, real-time monitoring. Near-infrared (NIR) spectroscopy measures glucose, lactate, ammonia, and other metabolites through fiber optic probes. Raman spectroscopy provides molecular fingerprints for substrate and metabolite quantification with less water interference than NIR. Fluorescence probes measure NADH/NAD+ ratio (metabolic state indicator). Dielectric spectroscopy measures viable cell density and physiological state. Implementation involves: building calibration models using chemometrics (PLS, PCA), validating across batches and scales, and integrating with control systems for feedback control. Benefits include reduced sampling, real-time decision making, and process understanding. Combined with soft sensors and models, spectroscopy enables advanced PAT applications.