Light transmission in knitted fabrics through polymeric optical fiber insertion for advanced textile applications

Smart textiles are prominent in the textile industry, with applications in various technical areas such as medicine, architecture, sports, and esthetic purposes, among others. Within this concept, optical fibers are classified as passive smart textiles and are highly attractive for clothing lighting and monitoring physiological parameters. This study aimed to present methods for inserting polymeric optical fibers into weft single knitted fabrics and verifying the loss of luminosity in them, analyzing the technical feasibility of developing e-textiles to be applied in monitoring. For such, weft knitted fabrics were produced by altering the optical fiber insertion methodology, defined as inlay insertion and insertion in the course direction, each subdivided into different methods. Light transmission was verified using a laser pen connected to the optical fiber. Images were captured and analyzed using LILP software to verify and quantify the loss of luminosity in each insertion method. Light transmission microscopy was performed to evaluate the surface of the polymeric optical fiber used. For the insertion techniques performed, inlay and by course direction, the result obtained for signal transmission was satisfactory; however, the inlay insertion methods presented lower light emission but lower luminosity loss than the insertion by course direction. This result is very interesting because it enables the development of weft knitted fabrics from the use of optical fibers for application in various types of monitoring.