Crystal measurement technologies for crystallization processes: Advances, applications, and challenges

Crystal measurement, especially on-line measurement, in industrial crystallization is always a challenging topic in the past years, which is crucial to precisely understand crystal dynamic behavior and product quality control. With the development of photoelectric sensing technology, various on-line/in situ crystal measurement technologies (CMTs) have been developed to extract crystal morphological information, detect crystal form and even microstructure. This paper critically reviews the principles, advantages, and disadvantages of various existing CMTs, and their applications in exploring new crystal forms, characterization, prediction, control of shapes and size of crystals. The future research directions are proposed from the aspects of improving measurement accuracy, developing novel technologies for complex crystal behavior measurement, and promoting the application of CMTs in industrial crystallization. On balance, this review aims to enhance the awareness of scientists and engineers across industry and academia on CMTs, further promoting the development of automation and intellectualization of industrial crystallization processes.