Flat Yarn Fabric Substrates for Screen-Printed Conductive Textiles

Herein, flat yarn-based polyethylene terephthalate (PET) fabrics as substrates for screen printing conductive inks are described. The effect of the screen-printing parameters, such as the screen mesh size (70 or 120 pixels in.(-1)) and the number of printing cycles, is investigated. The uniformity of the screen-printed layers and their electrical properties are directly related to the yarn shape, substrate roughness, and printing conditions. Minimum average sheet resistance of 16 +/- 3 m omega sq(-1)is achieved on the flat yarn PET fabrics, and there is little change in the electrical performance after 1000 bending cycles. To demonstrate the impact of yarn shape on an E-textile application, wearable antennas are fabricated using the screen-printed PET fabrics. The antennas are designed to operate at 2.4 GHz, which is a widely used unlicensed frequency for public wireless local area network services, Bluetooth, and radio frequency identification (RFID) services. The effects of the uniformity and conductivity of the printed layers on the antenna performance are analyzed. In open-area field tests, the textile antennas show better performance than commercial antennas. The results of this study will help improve the understanding of how the ink/substrate interface affects the screen-printing process and to advance the manufacturing technology for conductive patterns.