Integration of polymer optical fibers in textiles by sewing

Optical fibers are based on the principle of total internal reflection. Light is guided within a core surrounded by a cladding with a lower refractive index. Polymer optical fibers (POFs) are more flexible than glass fibers and can therefore be integrated into flexible substrates, such as textiles. They can thus be used in smart textiles for data transmission, sensor technology, or even for lighting.

Previous approaches to integrating POFs into textiles include, for example, weaving or knitting the POFs into the fabric [1,2]. However, since the optical fibers are less flexible than conventional yarns, they can be damaged during these processes, which disrupts the total internal reflection process and reduces the optical fiber’s performance.

In a recent project, we therefore investigated whether fine POFs can be sewn onto various woven and knitted fabrics without damaging the POF cladding. For each sample, 10 POFs, each 30 cm long, were sewn on using a zigzag stitch. The pull-out forces were measured for all materials, with coarser fabrics showing higher values. In addition, light transmission through the sewn-on POFs was examined. In this measurement, the coarser fabrics showed more POFs with reduced transmission, i.e., with a cladding damaged by the sewing process.

These results suggest that the thread tensions and the presser foot must be adjusted to the specific fabric in order to achieve an optimal combination of high light transmission and high pull-out force.

[1] Yamada, Y. Textile-integrated polymer optical fibers for healthcare and medical applications. Biomed. Phys. Eng. Express 2020, 6, 062001.

[2] Nascimento, L. M.; Porto, B.; Bessa, G. C.; Rincon, L. M.; Steffens, F. Light transmission in knitted fabrics through polymeric optical fiber insertion for advanced textile applications. Mater. Today Comm. 2024, 40, 109478.