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Size and Shape Characterization of Ensembles of Crystalline Powders


Webinar on

Size and Shape Characterization of Ensembles of Crystalline Powders

5th October 2023 at 3pm (UK time)



Particle size and shape distribution (PSSD) significantly impacts the macroscopic properties of powders, influencing attributes such as flowability, filterability, and compressibility. Particularly noteworthy are needle-like and plate-like particles, prevalent in pharmaceutical and agrochemical industries, presenting considerable manufacturing hurdles. Accurately characterizing PSSDs of particle ensembles is crucial for effective process design, modeling, and control to address specific manufacturing challenges arising from these unfavorable shapes.


Various techniques have been proposed and deployed at laboratory and pilot scales to characterize the PS(S)Ds. State-of-the-art methods, like laser diffraction, focused beam reflectance measurement, and Coulter counter, assume spherical shapes and describe particles using a single size descriptor - the sphere's diameter. While this assumption may suffice for quality control objectives, it can misguide practitioners when dealing with products exhibiting needle- or plate-like morphologies due to their asymmetric shapes. Emerging alternatives like Malvern's Morphologi and BlazeMetrics probes are enhancing traditional techniques by enabling shape resolution of particle ensembles. However, these devices often consolidate shape features into a single size descriptor, and obtaining high time-resolution data can be challenging. Moreover, even when shape features are not lumped, these devices typically offer a maximum of two size descriptors—length and width—adding to the challenge of characterizing plate-like particles.


Over the last decade, we have addressed these challenges to obtain high time-resolution data and characterizing particles using one, two, or three size descriptors. To this end, we have developed two innovative techniques: an online stereoscopic imaging device, the DISCO [1,2], and an offline combined imaging and confocal microscopy device, the Petroscope [3]. These techniques accurately resolve the size and shape of particle ensembles, enabling a deeper understanding of their characteristics. In this talk, we will delve into the multiple facets of our approach, highlighting how we overcame these challenges, comparing our techniques with industry standards, and demonstrating how the insights gained through precise process monitoring have enhanced the design and control of processes relevant to industry [4].



[1] Rajagopalan, A. K.; Schneeberger, J.; Salvatori, F.; Bötschi, S.; Ochsenbein, D. R.; Oswald, M. R.; Pollefeys, M.; Mazzotti, M. A Comprehensive Shape Analysis Pipeline for Stereoscopic Measurements of Particulate Populations in Suspension. Powder Technol. 2017, 321, 479–493.


[2] Binel, P.; Jain, A.; Jaeggi, A.; Biri, D.; Rajagopalan, A. K.; DeMello, A. J.; Mazzotti, M. Online 3D Characterization of Micrometer-Sized Cuboidal Particles in Suspension. Small Methods 2023, 7 (1), 2201018.


[3] Neoptolemou, P.; Vetter, T.; Cruz-Cabeza, A.; Rajagopalan, A. K. Combined Imaging and Chromatic Confocal Microscopy Technique to Characterize Size and Shape of Ensembles of Cuboidal Particles. ChemRxiv. 2023; https://doi.org/10.26434/chemrxiv-2023-nw1hs


[4] Bötschi, S.; Rajagopalan, A. K.; Rombaut, I.; Morari, M.; Mazzotti, M. From Needle-like toward Equant Particles: A Controlled Crystal Shape Engineering Pathway. Comput. Chem. Eng. 2019, 131, 106581.


This webinar will be presented by Ashwin Kumar Rajagopalan, Lecturer in Chemical Engineering, University of Manchester.


If you wish to register please contact christine.stevenson@strath.ac.uk


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