Development of high-temperature resistant e-textile structures with high data transfer quality for wearable electronic applications

In recent years, new and practical products have emerged to meet user demands with rapid development in science and technology. Electronic textiles, which are formed by the combination of electronic industry and textile science, meet the needs of people in different fields such as health, military, space, and medicine. In order to obtain e-textile structures and to develop new technologies in this field, scientists working in different disciplines ranging from polymer chemists to physicists, from textile engineers to bioengineers are working together. The e-textile structure is different from traditional electronic systems because it is an electronic system that is woven, knitted or incorporated into the composite fabric. The electrical and physical properties of electronic textiles work symbiotically and affect the functions and properties of each other. Electronic textiles can include a variety of electronic components such as sensors, video cameras, microprocessors, actuators, batteries. Recently, there has been a growing awareness of emergency situations involving large numbers of civilians in large populated areas. Professional rescue teams should minimize their risks while maximizing their effectiveness in performing their duties in scenarios such as major fires, earthquakes, floods, terror incidents or major industrial accidents. Along with the political supports provided within this scope, further support studies have been initiated to monitor and coordinate the activities of emergency support personnel against catastrophic events continuously. In these scenarios, with the emergence of wearable electronic devices, developments in information and communication technologies play a primary role. With the development of electronic textiles, information infrastructures are fully integrated into clothes that collect, process, store and transfer information about the user and the surrounding environment. In this study, it is aimed to develop e-textile structures with high data communication quality which are resistant to high temperatures for wearable electronics applications. Heat and flame protection textile theories were examined and the parameters such as melting temperature, pyrolysis temperature, combustion temperature and limit oxygen index (LOI) values were evaluated. Based on these parameters, six different fabrics were determined. These fabrics are made of woven, knitted and nonwoven based aramid reinforced aluminum laminate, aramid, glass fibre, viscous rayon and PBI fibers. The fabrics are prepared in various sizes according to the test methods specified in TS EN ISO 11612 (Protective clothing - clothing to protect against heat and flame). The samples are 200x160 mm according to ISO 15025 (Protective clothing -- Protection against flame -- Method of test for limited flame spread) standard, 140x140 mm according to EN ISO 9151(Protective clothing against heat and flame -- Determination of heat transmission on exposure to flame) and 230x70 mm according to EN ISO 6942 (Protective clothing -- Protection against heat and fire -- Method of test: Evaluation of materials and material assemblies when exposed to a source of radiant heat) standard. Six different fabrics, which are resistant to high temperatures, are combined with different types of conductive yarns (steel, copper, silver coated) to form an e-textile circuit line in sandwich form. Three different sewing machines were used to combine conductive yarns with outer fabrics. The first is the ultrasonic welding sewing machine. Three different parameters such as power, pressure and velocity were used for combining the lining fabric with the outer fabric by ultrasonic welding. By changing the parameter values, an electronic textile structure was tried to be formed by ultrasonic welding. In the case of stable bonding between the layers, it was determined that the aramid-viscous blended liner was deformed. For this reason, the ultrasonic welding technique has been eliminated in the study. The other method is the hot air welding seam technique. Although working with fabrics in different temperatures and different feed speed, short circuit due to the inability to be an orientated structure formed in the structure of the conductive yarn and sudden deviations in the resistance occurred. For this reason, the hot-air welding method has been eliminated. As an alternative method, the zigzag sewing machine was used to fix the conductive yarn to the lining fabric. For each test sample, conductive yarns prepared at the relevant length are fixed to the area marked on the liner by zigzag sewing method. After the conductive yarn liner is fixed to the fabric, the liner fabric and the outer fabric are sewn together, with the surface of the conductive yarn corresponding to the rear surface of the outer fabric. The sandwich structure is formed by this joining and the conductive yarns are prevented from direct contact with the outer surface. Operating characteristics of e-textile samples in terms of high-temperature resistance (limited flame spread, convective heat transfer, radiant heat) and electrical properties (conductivity and signal quality) were tested. As a result of the limited flame splash test, all fabrics were at A1 protection level and all fabrics were at B1 protection level as a result of convective heat test. In addition, as a result of radiant heat test, the protection level of aluminized fabrics was higher than PBI and viscous fabrics. Linear resistance values and signal quality of e-textile structures were compared before and after thermal tests and variance analysis (ANOVA) was used to determine whether the fabric types and yarn types had a significant difference between the average absolute linear resistance and data transmission quality. In cases where significant differences were detected, multiple comparison methods (Bonferroni, Scheffe or Tamhane test statistic) was applied in order to determine which group or groups were caused by this difference. As a result of thermal tests, it has been determined that in some e-textile structures, silver-plated conductivity yarns have ruptured and generally silver-coated conductive yarns show lower performance than copper and steel conductive yarns. Particularly in limited flame spread and convective heat test, the rate of loss data on silver yarns is over 30%. There was a reduction in the data transmission quality of conductive yarns after thermal tests for all yarn types and fabric types. When the signal-to-noise ratio (SNR) according to the yarn types is examined, it is understood that the average of SNR values for all yarns is above 40. This is the amount that can be considered successful in terms of data transmission quality. However, after all thermal tests, the data transmission quality decreased by approximately 10% on average. Compared to the SNR value of the fabric types, the aluminized fabric laminated to the knitted aramid fabric showed significant performance loss after the limited flame spread and convective heat tests. In addition, it was statistically determined in the conductivity and high data transfer quality measurements, the sample of aluminized fabric laminated to nonwoven showed higher performance than the samples manufactured using other fabrics. As a result, a highly functional e-textile structure that is resistant to high temperatures with smooth surface appearance and high data transmission quality has been developed. It is proposed that the developed e-textile structure is promising for the applications of wearable technologies, technical textiles, military clothes, protective clothing and spacesuits.