Classifying organic crystals via in-process image analysis and the use of monitoring charts to follow polymorphic and morphological changes

Measurement, modelling, and closed-loop control of crystal shape distribution: Literature review and future perspectives

“…However, for on-line monitoring, optimisation and control of shape and size distributions in a crystalliser, it is essential to accurately and efficiently obtain 3D crystal information of the whole crystal population and the associated properties. Of the many techniques [1,[41][42][43][44][45][46][47][48][49][50][51] for the imaging and reconstruction of 3D objects, optical imaging and image analysis techniques proved to be the most promising ones for 2D shape measurements [1,17,19,23,24,26,29,30,32,34,37,39,[52][53][54], and the techniques that are likely the most suitable ones for obtaining 3D crystal shape, hence growth rate of each crystal face, have made some advances in recent years [1, 45-50, 55, 56]. This is a very active research area with huge challenges and opportunities to innovatively develop process instrument and/or process probes and the associated image processing and shape reconstruction software for the real-time monitoring, optimisation and control of particulate processes.…”

“…Various shape descriptors have been developed in the last two decades, for example via deriving a new set of shape descriptors using the size measures of particles, or spectral or functional mathematical approaches such as the Fourier descriptors [1,17]. However, with the advances of 3D shape measurement and prediction, the actual 3D particle shape could be described and determined through experiments and modelling, hence 3D crystal shape and CShD can become the direct and accurate description of particle shapes in the studies of crystallisation processes and particulate systems.…”

“…Calderon de Anda et al [19] have investigated the use of the GlaxoSmithKline's imaging system for monitoring the crystallisation on-set and dynamic transition from one polymorph to another during crystallisation of LGA crystals. A multi-scale image analysis method [26,59] was developed and used to derive monitoring charts [17], and then to calculate the real-time growth rates associated with the evolution of the length and width for the needle-like -polymorphic form of LGA [60].…”

Highly Unusual Triangular Crystals of Theophylline: The Influence of Solvent on the Growth Rates of Polar Crystal Faces

“…[5][6][7][8][9][10][11] Understanding these phenomena is not only of academic importance, but also critical in many industrial sectors since the behavior of crystalline materials can be strongly influenced by crystal habit. [12][13][14] For example, in many applications the shape and size of particles must be carefully controlled to ensure that product performance is consistent from batch to batch. 12,[14][15][16] Furthermore, while the process of generating a desired particle size and morphology profile in a batch of material has traditionally been performed post crystallization through techniques such as milling and micronisation, 17,18 it is more desirable to gain sufficient control of the crystallization step such that crystals with optimum characteristics are grown directly.…”

“…[12][13][14] For example, in many applications the shape and size of particles must be carefully controlled to ensure that product performance is consistent from batch to batch. 12,[14][15][16] Furthermore, while the process of generating a desired particle size and morphology profile in a batch of material has traditionally been performed post crystallization through techniques such as milling and micronisation, 17,18 it is more desirable to gain sufficient control of the crystallization step such that crystals with optimum characteristics are grown directly. [18][19][20] For these reasons, focus has recently been directed to gaining further control and understanding of crystallization processes.…”