Fiber Diameter Analyzer for SEM (Electrospinning & Filters)

Measure fiber diameters from scanning electron microscope images of electrospun nanofiber mats, filter media, nonwovens and technical textiles. Instead of drawing 100 lines by hand in ImageJ, upload the images and get the full length-weighted diameter distribution with its confidence interval, beads, fiber alignment, quality checks and a PDF report.

Try it in one click: leave the image list empty and press Start. The Actor generates four synthetic nanofiber images with known diameters and beads, analyses them and compares the result with the truth. Demo runs are free.

What you get

Output	Content
Dataset item	length-weighted mean diameter ± SD, 95 % confidence interval of the mean, median, D10/D50/D90, CV, fiber segments and length measured, beads, alignment index and main direction, coverage, quality status and checks
REPORT.pdf	main results, detection check image, length-weighted distribution, orientation histogram, results per image, method, quality checks, traceability
segments.csv	one row per fiber segment: length, mean and median diameter, orientation, position
control-sheet.jpg	every image with fiber outlines, measured axes (yellow), excluded crossings (grey) and beads (red)
summary.json	all statistics in machine-readable form

Who it is for

• Electrospinning labs tuning voltage, flow rate, concentration or humidity
• Filter media and membrane developers (air, water, face masks)
• Tissue engineering and biomaterials groups reporting scaffold fiber diameters
• Quality control of nonwovens and technical textiles
• AI agents that need fiber statistics from SEM images (callable through the Apify MCP server)

How it works

1. The pixel size comes from the microscope metadata (Zeiss or Thermo Fisher TIFF), the scale bar of the data band, or the value you give.
2. The fiber axes are traced (skeleton of an inclusive fiber mask) and crossings are located.
3. The diameter is measured like a CD-SEM measures a line width: at each axis point, on the intensity profile perpendicular to the fiber, as the full width at half maximum between the local background and the peak, with sub-pixel interpolation. It does not depend on a threshold setting. On isolated fibers 8 to 40 pixels wide it reads within 0.6 pixel of the truth.
4. Crossings, fiber ends and beads are excluded, because no width can be measured there.
5. Statistics are weighted by length. Confidence intervals come from a bootstrap over fiber segments (not over pixels, which are not independent).
6. Beads (spindle-shaped defects) are counted with a prudent rule, so the count is a lower bound: beads on a crossing or under other fibers are not counted.
7. Fiber alignment is summarised by an index from 0 (random) to 1 (fully aligned) and a main direction.
8. Eight automatic checks rate the run green, amber or red: scale consistency, resolution, segments measured, precision, share of the axis excluded, consistency between images, contrast and saturation.

Accuracy

On synthetic nanofiber mats with known diameters (blur, noise, depth, crossings and beads included):

True length-weighted mean	Measured	95 % CI of the mean
295 nm (demo, 28 fibers per image)	292 nm	284–300 nm
299 nm (dense mat, 38 fibers per image)	295 nm	287–304 nm
148 nm (about 7 px per diameter)	153 nm	150–156 nm
305 nm (aligned mat)	302 nm	293–311 nm

Limit: in very dense mats of thick fibers, fibers partly hidden by others read too thin (−6 to −11 % on synthetic mats of 600 nm fibers); the run then flags a large share of excluded axis.

Input example

{
  "imageUrls": [
    "https://example.com/mat-A-1.tif",
    "https://example.com/mat-A-2.tif",
    "https://example.com/mat-A-3.tif"
  ],
  "scaleBarNm": 5000,
  "sampleName": "PCL-12pct-15kV"
}

Set "reportLanguage": "fr" for a report in French. Use pixelSizeNm when the images have no data band, or nothing at all for original Zeiss or Thermo Fisher TIFF files.

Use 3 to 10 images of the same sample at the same magnification, with at least 8 pixels across a typical fiber. Images must be direct download links (TIFF, PNG or JPG, up to 60 MB each).

Pricing

You pay per image analysed. There is no charge for images that cannot be downloaded, and demo runs (no image URLs) are free.

Good to know

• Fibers must be brighter than the background (the usual SEM case). Tick fibersAreDark for the opposite.
• Only visible fibers are measured. Fibers lying side by side along their whole length can read as one wider fiber.
• Hollow, ribbon-like or highly porous fibers are not distinguished.
• This is automated image analysis, not an accredited (ISO/IEC 17025) laboratory measurement.
• Need a report reviewed and signed by a materials imaging scientist? A verified analysis service is available on request (contact through the Actor's issues tab).