Particle shape using digital image analysis

Citation

(2005), "Particle shape using digital image analysis", Pigment & Resin Technology, Vol. 34 No. 1. https://doi.org/10.1108/prt.2005.12934aab.002

Particle shape using digital image analysis

Particle shape using digital image analysis

Keywords: Particle size measurement

The development of fully automated digital image analysis techniques to determine particle shape and size has meant that particle shape measurement is being used increasingly in routine applications. Malvern's FPIA-2100 analyser for wet measurements and the PharmaVision 830 system for dry applications allow linking of subtle variations in particle form to final product performance.

Today's technology requires the collection of two-dimensional representations of three-dimensional particles, and Malvern systems use novel approaches to ensure the strict control of particle orientation necessary for the generation of accurate and reliable measurements. The FPIA- 2100 is based on flow cytometry using a sheath flow mechanism to analyse wet suspensions and emulsions. The instrument calculates diameter and circularity parameters for each particle and displays results as a scattergram, allowing the establishment of a “fingerprint” for each sample.

The sheath flow mechanism aligns particles with their major axis in the direction of flow. This ensures that every particle is held in focus and oriented with its largest surface area facing the camera.

The PharmaVision 830 is based on automated microscopy, rapidly analysing hundreds of thousands of particles for statistical significance. For each particle a series of morphological parameters is calculated. A sample preparation device uses compressed air to disperse material into a sealed chamber. Particles then settle under gravity on to a glass plate, adopting their most mechanically stable position, with the largest surface area facing the camera.