Electrical Characteristics and Signal Transmission Characteristics of Hybrid Structure Yarns for Smart Wearable Devices

摘要

Twisted Copper Filaments (TCF) have been made by a yarn covering process in order to transmit signals and powers for electronic textiles. The 560 den. poly urethane filaments were covered in S-twist direction by urethane-coated copper wires. Two TCF twisted in Z direction were further covered in S direction by PET filaments to make final hybrid structure yarns (HSY). The HSY prepared was proportionally increased in apparent resistance along with measurement length, and showed resistivity of 0.00414 Omega.m. The number of ply was critical in terms of resistance variation, showing a linear increase of resistance with ply number. The twist factor, however, was not so significant without a slight decrease for severe twist level. Resonance Frequency, S11 (reflection), S21 (transmission) were measured and compared in order to examine the feasibility of applying to electrical signal transmission for wearable textiles. As expected, amplitude of resonance frequency was significantly decreased mainly due to increase of capacitance caused by length increase. It has been shown that S11 and S21 has been increased and decreased, respectively due to increase of transmission distance. While resonance frequency has been kept along with the ply number, S11 and S21 were decreased and increased, respectively according to decrease of copper fiber. Final filaments were found to be changed in resonance frequency mainly due to the change of di-electricity and thus capacitance caused by PET covered on it. It have been concluded that while resonance frequency was primarily determined by filament length and dielectric constant of covering yams, S11 and S21 were mainly determined by measurement length and ply number.