The N95 mask sample was scanned by lab-based X-ray micro-scale CT scanner (Zeiss Xradia 620 Versa, Carl Zeiss Inc.). 501 projections were obtained for the specimen. The standard reconstruction algorithm is used to reconstruct sample. The voxel resolution at 350 nm with the narrower (ca. 350 μm x 350 μm) field of view was achieved.