Crystal growth measurement using 2D and 3D imaging and the perspectives for shape control

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

“…As shown in Sections 4-6, the ability of on-line, accurate measurement of crystal growth not only directly provides crystal growth kinetics for MPBMs, but also is essential to the development of real-time MPBM based feedback control strategies. Many recent researches have proved the feasibility of using high speed on-line imaging for crystal size and shape measurements, in particular for 1D and 2D characterisation [1,. 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.…”

“…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.…”

“…the facet growth rate (m/s) as a function of such variables as supersaturation, solvent, impurity as well as crystal size, are needed by morphological population balance models (MPBMs) [1]. MPBMs can be used in multi-objective optimisation to obtain the optimum operating condition, such as an optimum supersaturation curve, that leads to the desired CShD as well as yield and other objectives.…”

Particle shape characterisation and classification using automated microscopy and shape descriptors in batch manufacture of particulate solids

“…One of the properties for particulate products is shape, not only because it is now recognized that size alone as often defined as volume equivalent diameter is over simplified and sometimes misleading, but also because shape can affect product performance properties such as bioavailability of drug particles. Optical microscopy has been proved to be one of the most effective techniques to determine particle shape and size off-line or on-line (Brittain, 2001; Calderon De Anda, Larsen, Rawlings, & Ferrier, 2006;Larsen, Rawlings, & Ferrier, 2007;Wang, Calderon De Anda, & Roberts, 2007;Wang, Roberts, & Ma, 2007). The images can be analyzed using image analysis algorithms (Zhang & Lu, 2004) to obtain particle shape information, which is often defined by some descriptors that have physical meanings such as aspect ratio.…”