Three-dimensional printing technology is being increasingly applied in a multitude of sectors. However, this technology is not generally applied in the same way as in other sectors, possibly due to the difficulty of adhesion between the polymer and the textile substrate. A textile garment is subjected to wear and tear during its lifetime, and a low tensile strength or rubbing resistance hinders a garment in most of the applications of this type of research. This study examined the influence of the characteristics of the cotton textile substrate, such as the weave structure and the yarn thickness, on the tensile strength of a 3D-printed element with conductive filament. Starting from the fabric with the highest tensile strength, different prints were made using this technology to incorporate conductive and heating properties into the fabric. The results validate the possibility of providing new properties to the textile by means of this technology; however, the correct selection of the textile used as a base substrate is important.

The combination of flexible-printed substrates and conventional electronics leads to flexible hybrid electronics. When fabrics are used as flexible substrates, two kinds of problems arise. The first type is related to the printing of the tracks of the corresponding circuit. The second one concerns the incorporation of conventional electronic devices, such as integrated circuits, on the textile substrate. Regarding the printing of tracks, this work studies the optimal design parameters of screen-printed silver tracks on textiles focused on printing an electronic circuit on a textile substrate. Several patterns of different widths and gaps between tracks were tested in order to find the best design parameters for some footprint configurations. With respect to the incorporation of devices on textile substrates, the paper analyzes the soldering of surface mount devices on fabric substrates. Due to the substrate’s nature, low soldering temperatures must be used to avoid deformations or damage to the substrate caused by the higher temperatures used in conventional soldering. Several solder pastes used for low-temperature soldering are analyzed in terms of joint resistance and shear force application. The results obtained are satisfactory, demonstrating the viability of using flexible hybrid electronics with fabrics. As a practical result, a simple single-layer circuit was implemented to check the results of the research.

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.