Electric field-assisted micro-scale direct ink writing for electronic textiles

High-performance Kevlar fabric is widely employed in protective clothing. A recent trend involves the fusion of flexible conducting materials with protective textiles to create multifunctional E-textiles with microscale circuits. Poly(3,4-ethylenedioxythiophene): poly( styrenesulfonic acid) (PEDOT:PSS) stands out as one of the most promising conducting polymers for flexible electronic applications, owing to its remarkable electrical, chemical and mechanical properties. Until recently, the production of PEDOT:PSS material on Kevlar fabric predominantly relied on dip coating and drop coating methods, presenting significant challenges for achieving microscale customized applications. Direct ink writing (DIW) has gained popularity due to its ability to fabricate a wide range of materials with programmed patterns and three-dimensional architectures, making it increasingly attractive for electronic printing. However, the rough surface of textiles and the die-swelling phenomenon exhibited by DIW printable materials have posed challenges for microscale E- textile fabrication. In previous studies, it was discovered that an electric field could facilitate material deposition on rough surfaces. This work investigates the potential to print PEDOT:PSS-based material patterns on rough textiles with a microscale resolution. It not only validated the effectiveness of the electric-field- assisted direct ink writing when printing PEDOT:PSS-based conducting inks on Kevlar but also identifies significant factors for achieving the microscale printing resolution. Additionally, this work characterizes the resistivity of the printed micro-traces and circuits. This research opens up possibilities for further exploration in customizing microscale circuits on various textiles.