Measurement outputs Measurement outputs
Measurement type(s) used Equivalent Spherical Diameter (ESD)
Justification for this choice
Measurement type chosen based on particles type: particles were very small, mostly round, and transparent (see example of images below). VisualSpreadsheet© software version 4.15.1. identifies pixels that comprise a particle by distinguishing them from the image background taken automatically at each run. Among other parameters, the software estimates the Area-Based Diameter (hereafter ABD) and the Equivalent Spherical Diameter (hereafter ESD). ABD is the diameter calculated based on a circle with an area equal to the ABD area. The ABD area is determined by the number of dark pixels in the binary imaged particle, excluding inner light pixels. ESD is the mean value of 36 feret measurements. Feret measurements are the perpendicular distance between parallel tangents touching opposite sides of the particle (VisualSpreadsheet 5 Particle Analysis Software manual). ABD would be expected to underestimate the size of particles with internal transparent components, while ESD would be expected to overestimate the size of particles with protrusions or flagella (Owen et al., 2022).