Terahertz tech could spot fake fabrics

Scientists from the National Physical Laboratory (NPL) in the UK are developing a technique called terahertz time-domain spectroscopy to fight textile counterfeiting.

The approach uses a beam of terahertz radiation, a band of electromagnetic radiation that falls between microwaves and infrared light, to record a distinctive spectral pattern for an item of fabric.

The pattern of beam scattering and absorption generated by the textile under test provides a unique signature which could be used to indicate whether or not a fabric is genuine or counterfeit, say the researchers, whose work is published in the journal Applied Optics (Issue 19, pp. 4433-4437)

This research examined fabrics made from wool, cotton, linen, silk and mixed fibres, all of which demonstrated distinct terahertz transmission properties.

The technique could clearly distinguish between fabrics that looked and felt similar but that had different compositions, according to the NPL researchers. For example, it could tell the difference between plain wool and the more expensive merino wool, as well as between natural and synthetic silk.

John Molloy, who worked on the project at NPL, said: "Counterfeit clothes can look and feel almost exactly like the real thing and so customs officials need technological assistance to spot them."

The next stage will be to test batches of the same type of fabric from the same manufacturer in a potential collaboration, according to the researchers, who carried out the research in collaboration with the Institute of Monitoring of Climatic and Ecological Systems in Russia.

It will also be necessary to create a database of the terahertz transmission properties of many different fabrics and to study further the relationship between these and the properties of the fabrics themselves, they add.

It is estimated that counterfeiting costs the £37bn ($57bn) UK fashion industry - including designer brands and retailers - around £3.5bn each year.