Manufacturing and characterization of conductive threads based on twisting process for applying smartwear

Abstract A basic study was conducted to manufacture conductive composite threads for use in textile-type electrodes and circuits for smartwear that can be sewn, embroidered, and knitted. The two-types of poly(ethylene terephthalate(PET) filament with a circular cross-section(SD), and an oval cross-section and curved surface(DT), and the conductive yarn was selected as a silver-coated polyamide(AP). The samples were produced two-ply PET yarn as the first twist, then using AP as the second twist, and both processes were applied with 100, 200, 500, and 1,000 TPM. As the number of twists increased, the packing density of samples increased, and the bulkiness of DT was decreased. In addition, the elongation at break tended to increase as the number of twists increased, especially for samples manufactured with DT with a curved surface appeared larger. The linear resistance results increased as the number of second twists in which the conductive yarn was twisted increased. It was confirmed that the area of AP exposed to the outside was more prominent in SD-AP, resulting in decreased linear resistance. Based on the results, samples that have the excellent mechanical and electrical performance were selected to manufacture textile-type electrodes that embedded leg sleeves to measure the surface electromyography(sEMG) signal collection performance. The signal-to-noise ratios(SNR) of textile-type electrode manufactured by SD - AP and DT - AP were 4.54 and 14.96, respectively, confirming the possibility of collecting EMG signals. Thus, this study is expected to be applicable to a wider range of fields than smartwear.