Particle size and particle shape using image analyzers

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	Morphologi G3
	FPIA - 3000
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What is particle shape

What exactly is particle size and particle shape?

Describing a 3D particle is often a more complex matter than it first appears.For simplicity it is convenient to describe particle size as one single number. However, unless the particle is a perfect sphere (which is rare in ‘real-world’ samples) there are many ways to describe the size of a particle.

Image analysis systems capture a 2-dimensional image of the 3D particle and calculate various particle size and particle shape parameters from this 2D image. Calculating size and shape parameters like the ones shown in the list below allow even the most subtle differences to be identified and quantified.

Parameter	Example value	Definition
CE diameter (µm)	904.14	The diameter of a circle with the same area as the particle
Length (µm)	1306.35	All possible lines from one point of the perimeter to another point on the perimeter are projected on the major axis (axis of minimum rotational energy). The maximum length of these projections is the length of the object. All possible lines from one point of the perimeter to another point on the perimeter are projected on the minor axis. The maximum length of these projections is the width of the object.
Width (µm)	678.54	Largest distance between any two pixels in particle
Max. Distance (µm)	1318.07	Actual perimeter of particle
Perimeter (µm)	3619.42	Axis of minimum rotational energy
Major axisº	105.52	Actual area of particle in sq. microns
Area (µm2)	371550.78	Number of pixels in particle
Area (pixels)	215018	Circumference of equivalent area circle divided by the actual perimeter of the particle
Circularity	0.785	= 2 x square root (π Area)/Perimeter
HS Circularity	0.616	High sensitivity circularity (circularity squared) =4 πArea/perimeter²
Convexity	0.919	Convex hull perimeter divided by actual particle perimeter
Solidity	0.905	Actual particle area divided by convex hull area
Aspect ratio	0.519	Width divided by length
Elongation	0.461	1 - aspect ratio
Intensity mean	61.310	Average of all the greyscale values of every pixel in the particle
Intensity standard deviation	29.841	Standard deviation of all the greyscale values of every pixel in the particle
Centre x position (µm)	6898271.5	x co-ordinate of centre of mass of particle
Centre y position (µm)	1797186.3	y co-ordinate of centre of mass of particle

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	Why is particle shape analysis important?

Image analysis systems from Malvern:

Malvern offers three image analysis systems. These image analysis systems have been developed specifically for routine and repeatable particle size and particle shape analysis. The choice of instruments depends upon the nature of the application and sample form:


	Morphologi G3 - High sensitivity particle analyzer The Morphologi G3 is based on automated microscopy and enables characterization of particle size, particle shape and particle count in wet and dry materials in the range 0.5µm to 3000µm.


	Sysmex FPIA-3000 - for wet samples (suspensions and emulsions). The Sysmex FPIA-3000 is based upon flow cytometry and enables characterization of particle size and particle shape of wet materials in the range 0.8µm to 300µm.