Influence of Pretreatments on the Conductivity of Flexographic Printed Electronics on Flexible Substrates

The development of electronic textiles (e-textiles) has advanced significantly thanks to the integration of printing technologies such as flexography, which enables the efficient and reproducible production of conductive circuits on fabrics. This study evaluates the impact of different surface pretreatments (hydrophobic and oleophobic) on the electrical conductivity of flexographically printed circuits on a variety of polyester textile substrates. Key parameters such as grammage, fabric type and surface uniformity are analyzed using stereomicroscopy and profilometry techniques to characterize conductive ink distribution. The results demonstrate that oleophobic pretreatment is more effective at reducing the resulting electrical resistance, promoting better ink adhesion and distribution. Among the fabrics with the best results, those with a more regular and compact structure, such as 15 thread/cm and 666.7 dtex polyester taffeta, show homogeneous ink coverage and the lowest electrical resistance (∼0.5 Ω/cm) compared to more irregular fabrics with discontinuities and higher resistance. The results show that uniformity in ink distribution, assessed by profilometry and color analysis, directly correlates with low electrical resistance. It can be concluded that the combination of a regular and compact textile structure, an adequate surface pretreatment, and a printing direction of the circuit pattern aligned with the weft permits optimizing the conductivity and quality of e-textiles produced by flexography.