Facile and eco-friendly room-temperature electrical-enhanced technology for conductive circuits electrohydrodynamic-printed directly on textiles with small usage of conductive fillers

Abstract

Flexible printed circuits are crucial for efficiently manufacturing electronic textiles. To achieve high conductivity with small usage of conductive fillers and avoid fabric shrinkages caused by high-temperature curing, an eco-friendly and high-temperature-free technology combining UV curing and chemical sintering with electrohydrodynamic (EHD) printing was innovatively proposed. The process integrating sequence was systematically investigated, along with in-depth analysis on surface morphology, electrical performance and enhancement mechanism. Results show that pre-treating fabrics using chemical sintering agent before EHD printing leads to an approximately parabola-like change in electrical resistance, and the “holes” formed by polymer aggregation deteriorates the uniform morphology of printed conductor. In contrast, treating printed lines by optimized integrating process facilitates the uniform and sufficient 3D-sintered structure. Electrical resistance was remarkably reduced by 93 % and successfully lowered to 1.24 ± 0.32 Ω even with 20 wt% Ag. The variation in resistance remained within 20 % after 3000 bending cycles and within 42 % after 10 washing times, exhibiting outstanding flexibility and washability. Additionally, application of as-prepared conductive circuits in electronic textile devices is demonstrated through the performance of ultra-high-frequency radio frequency identification (UHF RFID) antenna. Significant electrical enhancement based on small usage of conductive fillers in this work provides an efficient and green approach towards high-performance flexible circuits and e-textiles.