Real‐time supersaturation monitoring in cooling crystallization via hybrid electrical conductivity–ultrasonic sensor fusion

Abstract Real‐time monitoring of solution concentration is essential for controlling supersaturation and optimizing yield in cooling crystallization processes. We present a hybrid sensor fusion approach that combines electrical conductivity (EC) and ultrasonic (US) sound velocity measurements for in‐situ concentration monitoring of solutions during cooling crystallization. Temperature‐dependent EC and US models were developed and validated over a wide concentration range, encompassing both saturated and supersaturated states. A turbidity‐based analysis delineated the metastable zone and nucleation onset, revealing complementary sensor limitations: diminished EC sensitivity at low concentrations and particle‐induced US signal interference at high concentrations. An adaptive fusion algorithm exploited these complementary strengths to maintain a relative error below 5% across the full concentration range. This cost‐effective dual‐sensor strategy provides a robust alternative to spectroscopic techniques and can be readily adapted for real‐time supersaturation control in diverse inorganic crystallization systems.