Fiber diameter measurement for electrospun fibrous mats using scanning electron microscopic images: a protocol toward standardized characterization

Fiber diameter is a key characteristic of electrospun fibrous mats. This study aims to take a step forward in developing a protocol for standardized measurement of fiber diameter using scanning electron microscope (SEM) images. Manual and Automatic measurement (AM) methods (General Image Fiber Tool: GIFT) are applied to SEM images at magnifications of 2 kx and 4 kx. Results suggest that measurement on a synthetic image composed of fibers with constant diameter in the range studied be reported as a reference for minimum measurement variability. Fiber Based Method (FBM) which considers one contribution from each fiber in a SEM image is introduced. It was found that the average, minimum and maximum fiber diameter could be different from results obtained by Conventional Method (CM) which considers all measurements on a SEM image. FBM is suggested to be a better representative of individual visible fibers and reduce the bias associated with unequal numbers of local measurements per fiber. In addition, bin size for fiber diameter histograms is suggested to be set between the pixel size of the image for AM or the average measurement variability for manual methods, and 20% of the span of fiber diameters. Furthermore, “Fiber Index” as a criterion for evaluation and reporting of fiber diameter along with average and standard deviation is introduced.