Manufacturing Cut-And-Sew Garment-Integrated Technologies: An Investigation Of Surface-Mount Fabrication For Electronic Textiles

Abstract

The current wearable industry often uses custom made techniques (e.g., craft-based, hobbyists) that utilized proprietary equipment in a laboratory setting with specific applications in mind. While craft construction of textile-integrated electronics is common, these methods are typically not efficient enough for larger-scale production. For larger-scale production, the barriers to textile- and garment-integration have restricted the ability to spatially distribute technology over the body surface, particularly sensing and actuating components that may rely heavily on or be strongly affected by their specific location on the body. Industrial fabrication of e-textiles requires an efficient and scalable process that allows spatial distribution of components with a careful balance of automation and human labor. This research project aims to develop, characterize, and assess a scalable manufacturing method for garment-integrated technologies that preserve user comfort and work within the constraints of typical apparel manufacturing processes while providing required electrical performance and durability needed by the system. We have developed a method for attaching discrete surface-mount components and characterized the method. The method uses an industrial pattern stitching machine to stitch conductive traces onto a fabric surface in a 2D pattern and a reflow technique to integrate electronic components. Several prototypes from small fabric swatches to completed e-textile garments were made and tested to evaluate the durability, efficiency, and effectiveness of the method. We show a durability of 3% joint failure after a 14-hour wear test with no insulation and 0% failure rate after a washability test with insulation for the best manufacturing conditions. To investigate the scalability of the method at a garment scale as compared to manufacture of non-electronic garments, forty pieces each of regular and temperature sensing fire-fighter turnout gear coat liner garments have been produced. This manufacturing case study was used to evaluate the successful functionality of the manufactured garments as well as the impact of integrating electronic technology on labor, equipment, and cost. The study results show that the average manufacturing time to produce a sensor-integrated thermal liner was 3.27 times higher than producing a regular thermal liner garment, given that all the materials, labor, and machines remain constant. The sensor-integrated thermal liner garment cost around 3.44 times more to produce compared to the regular thermal liner garment. However, further analysis showed that by optimizing some of the processes, and using fully functional machines and skilled laborers, the production cost of the same sensor-integrated garment could be cut down by almost 51% and if the production takes place in a developing country where labor cost is much lower than in developed countries, the cost of production could be cut down to as much as 72%. Moreover, it would require more skilled laborers and better training of the laborers to produce e-textile garments compared to regular garments. We show that with strategic design and using existing machines and tools, technologies could be integrated into clothing during the assembly process using existing apparel manufacturing technology without a significant impact on labor, equipment, and cost. Furthermore, results of this case study were used to identify the more abstract challenges including machine optimization, human errors, and process variables involved in transitioning from one-off production to a larger-scale context in a Cut-Make-Trim (CMT) factory setting. The manufacturing method could be potentially used as an alternative for manufacturing e-textiles in mass.