Multifunctional Electronic Textiles by Direct 3D Printing of Stretchable Conductive Fibers

The integration of functional fibers into wearable devices by traditional methods is commonly completed in weaving. A new post-weaving method of integrating fiber devices into textiles is needed to address the challenge of incorporating functional fiber into ready-made garments without tearing down the clothing and re-weaving. A 3D printing method to simultaneously fabricate and integrate highly stretchable conductive fiber into ready-made garments with designed patterns is presented. The fabricated sheath-core fiber consists of a styrene-ethylene-butylene-styrene (SEBS) shell and a Ga-In-Sn alloy liquid metal core. The SEBS shell guarantees the high stretchability (up to 600%) and flexibility, while the liquid metal core offers a high conductivity maintained at large deformation. It is shown that sophisticated patterns, which have millimeter-level-resolution that are difficult to be integrated into textiles by weaving, and even more laborious to be incorporated into ready-made garments, can now be easily modified and implemented into both textiles and ready-made garments by a time-saving and low-cost 3D printing method. Utilizing the electrical characteristics of the fiber in pre-designed patterns, on-clothing soft electronics can be printed directly. A printed on-clothing strain sensor, bending sensor, wireless charging coil, and a touch-sensing network are demonstrated to show the potential applications in wearable electronics.