Spectrally-selective SPR fiber-optic sensor for simultaneous monitoring of glucose, pH, and temperature in biopharmaceutical processes

In order to meet the requirements of real-time control of multiple parameters in biopharmaceutical processes, this paper proposes an SPR fiber optic sensor with spectral selectivity for simultaneous measurement of glucose concentration, pH value, and temperature. The sensor is a triple cascade structure, with an Ag film used to measure glucose concentration, PAA/CS self-assembly is performed on the Ag/TiO 2 surface for measuring pH, and Ag/MoS 2 /PDMS is used for measuring temperature. The innovation of this paper lies in utilizing the different optical properties of TiO 2 and MoS 2 and the response differences of functional films to different measured parameters, to endow the three-sensor band spectral selectivity, and achieve distinguishable and non-interfering synchronous responses of three parameters within the full spectrum (400–1700 nm). The experimental results showed that the sensitivity of sugar content (0–35 %) and temperature (−10–100 °C) were 5.29 nm/% and 6.8 nm/°C, respectively. At the same time, pH could be accurately measured in the range of 3.22–10.12, with detection limits of 0.151 %, 0.117 °C, and 0.043 pH, respectively, demonstrating good stability and covering the key range of typical fermentation processes. The functional film design and spectral selection mechanism proposed in this study have great potential for application in precisely grasping key parameters in biological fermentation and pharmaceuticals, and provide a new paradigm for the structural integration of multi-parameter sensors.