UV Curable Conductive Ink for the Fabrication of Textile-Based Conductive Circuits and Wearable UHF RFID Tags

Textile is a kind of emerging substrate for wearable printed electronics to realize recyclable smart products by versatile and low-cost screen printing. The high temperature sintering step is necessary to get high surface electrical conductivity, whereas most of the common fabrics have poor temperature endurance. Meanwhile, both rough surface and porous structure of fabrics are not beneficial to obtain high-resolution and high-quality circuits. In this work, the ultraviolet (UV) curable conductive inks with low-temperature and short-time curing were developed for screen-printing e-textiles, and the rheological behavior of conductive inks with different polymer contents was characterized in order to determine the ink formulation suitable for screen printing on fabrics. To demonstrate the usability of the developed ink in fabricating e-textiles, the conductive lines with different widths as well as the antenna for UHF RFID tags were screen-printed on plain nylon-woven fabrics. The geometric morphology and the electrical properties of the printed conductive lines were evaluated. The results showed that the screen-printed conductive lines have a minimum line width of 0.2 mm, highest conductivity of 6.02 × 10⁶ S m^-1, and good bending endurance at a bending radius of 5 mm. Also, the feasibility of UV curable conductive ink for a fabric-based electronic device was confirmed by the screen-printed antenna of UHF RFID tags, and the reading distance after five cycles of washing is still over 3.0 m. Generally, this work developed a kind of low-temperature curing ink characterized by direct screen printing on common fabrics and high electrical conductivity after curing, and it will facilitate the use of textiles as the screen-printed substrates for flexible and wearable electronic devices.