Fabric analyses by scanning electron microscopy

Our  analyses include

  • the determination of fibre diameter and fabric thickness
  • the pore sizes in the tissue and their distributions
  • the exact analysis of the weaving patterns
  • High-resolution images of the individual fibre structures
  • documentation of the quality and uniformity of the material (textiles, fabrics, microfibres, paper, etc.)

Corona, Covid19, protective masks, fabrics, textiles and pore sizes

Corona virus SARS-CoV-2

The corona virus SARS-CoV-2 is tiny!
Its diameter is only 125 nm, so it cannot even be seen with a light microscope.

Contagious droplets

The virus is usually transmitted via droplets in the air. Most droplets are also very small. About 5000nm ( 5µm).

Face mask: which fabric?

Homemade face masks should ideally be able to catch these droplets. To do this, the pores must at least be small enough that the droplets stick to the fabric.

Cotton bed sheet

The pores of this thin cotton fabric are very large (> 100 µm). The fabric can hardly retain droplets.

Old kitchen towel

Due to the tight weave structure of this tea towel, the pores are quite small. (< 20 µm). In double layer, droplets might be captured sufficiently well.

Meltblown fleece from OP-mask

This meltblown fleece from a surgical mask is not tightly woven, but because of the many layers it can catch droplets very effectively.

Respirators dictionary:

Face mask - e.g. self-sewn:
They are not a medical product and there are no regulations for their manufacture. The aim is to reduce the distribution of the wearer's possibly infectious droplets. However, they do not protect the wearer from infections. To be able to retain the droplets - which contain the carrier's corona viruses - the pores should be small enough. It is assumed that most droplets can be held back by pores that are about 5µm in size. The choice of fabrics and textiles should be based on this.

Op-Mask - MNS (Mouth and nose protection) - medical face mask :
The OP mask is a medical product. The main intended use is to protect patients against infectious germs and, in certain situations, to protect the wearer against splashes of possibly contaminated liquids. Source: DIN EN 14683:2019-10

FFP (Filtering Face Piece) respiratory protection devices - Filtering half masks to protect against particles:
The half mask covers the nose, mouth, and chin and may have an inhalation and/or exhalation valve. / These devices are designed to protect against both solid and liquid aerosols. They are classified according to filter performance and their maximum inward leakage. There are three device classes: FFP1, FFP2 and FFP3. Source DIN EN 149:2001+A12009
To protect against infection by the corona virus SARS-CoV-2, at least FFP2 class respiratory protection is required.

SEM Images of various fabrics