Development of a Fibre Optic pH Sensor Using Sodium Alginate Hydrogel for Monitoring in EV Battery Cooling Systems

The regulation of pH in electric vehicle (EV) battery cooling systems is paramount for mitigating corrosion, optimizing thermal conductivity, and prolonging system durability. Conventional pH monitoring methods predominantly employ electrochemical probes that are impractical for continuous, in-situ measurements in the confined, closed-loop environments characteristic of electric vehicle(EV) cooling systems. This study presents a pioneering, FBG-ApH sensor engineered with a sodium alginate hydrogel coating, tailored for seamless integration into EV battery cooling circuits. Sodium alginate, a biocompatible hydrogel, exhibits distinct pH-responsive optical properties, including changes in pitch and corresponding Bragg wavelength shifts, enabling real-time pH detection in coolant fluids. These wavelength variations arise from the modulation of the gap between the sodium alginate gel and the FBG-ApH sensor, facilitating precise, continuous monitoring of pH levels within the EV cooling system. The FBG-ApH sensor capitalizes on these optical transitions, which are relayed through the fibre optic medium to yield a continuous, precise pH profile without the introduction of conductive or potentially reactive components into the system. Experimental results reveal high sensitivity, with rapid, stable response to pH fluctuations, allowing for effective corrosion monitoring and the preservation of optimal thermal conductivity within the system. The FBG-ApH sensor thus represents a compact, high-performance, and sustainable alternative for realtime pH monitoring in EV cooling systems, contributing to enhanced operational safety, efficiency, and longevity