Less than 15% of the 92 million tons of clothing and other textiles discarded annually are recycled—in part because they are so difficult to marketplace surabaya sort.
“It’s like a barcode that’s woven directly into the fabric of a garment,” says Max Shtein, a professor of materials science and engineering at the University of Michigan and corresponding author of the study in Advanced Materials Technologies.
“We can customize the photonic properties of the fibers to make them visible to the naked eye, readable only under near-infrared light or any combination.”
Ordinary tags often don’t make it to the end of a garment’s life—they may be cut away or washed until illegible, and tagless information can wear off. Recycling could be more effective if a tag was woven into the fabric, invisible until it needs to be read. This is what the new fiber could do.
Recyclers already use near-infrared sorting systems that identify different materials according to their naturally occurring optical signatures—the PET plastic in a water bottle, for example, looks different under near-infrared light than the HDPE plastic in a milk jug.
Different fabrics also have different optical signatures, but those signatures are of limited use to recyclers because of the prevalence of blended fabrics, explains lead author Brian Iezzi, a postdoctoral researcher in Shtein’s lab.
“For a truly circular recycling system to work, it’s important to know the precise composition of a fabric—a cotton recycler doesn’t want to pay for a garment that’s made of 70% polyester,” Iezzi says. “Natural optical signatures can’t provide that level of precision, but our photonic fibers can.”
To develop the technology, the team combined Iezzi and Shtein’s photonic expertise—usually applied to products like displays, solar cells, and optical filters—with the advanced textile capabilities at MIT’s Lincoln Lab. The lab worked to incorporate the photonic properties into a process that would be compatible with large-scale production.