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A shape factor to characterize the quality of spheroids
1Department of Pharmaceutics, School of Pharmacy, University of London, UK.
The Journal of Pharmacy and Pharmacology
|February 1, 1994
Summary
A new shape factor, eR, quantifies particle spheroidal deviation and surface roughness. This factor effectively distinguishes between various symmetrical shapes, offering more detail than traditional aspect ratio analysis.
Area of Science:
- Particle characterization
- Image analysis
- Materials science
Background:
- Accurate particle shape description is crucial in many scientific fields.
- Existing shape descriptors like aspect ratio can be insufficient for complex particle morphologies.
Purpose of the Study:
- To introduce a novel shape factor, eR, for quantifying the deviation of particle shapes from a perfect spheroid.
- To assess the sensitivity of eR to both ellipticity and surface irregularities.
Main Methods:
- Development of a two-dimensional image analysis method to calculate the eR shape factor.
- Testing eR using model figures (squares, triangles, diamonds, stars) and comparing its performance with the aspect ratio.
Main Results:
- The eR shape factor successfully differentiates between polygonally symmetric figures where aspect ratio yields identical values.
- eR is sensitive to deviations from a perfect spheroid, including ellipticity and surface roughness.
- A perfect spheroid yields an eR value of 1.0.
Conclusions:
- The devised eR shape factor provides a more nuanced description of particle form compared to conventional methods.
- eR is a valuable tool for detailed particle shape analysis, particularly for irregular or non-elliptical particles.