Designing Silver Conductive Ink S-Curve Interconnects for Bio-potential Monitoring E-Textiles Via Material Deposition Fabrication

Electronic textiles (e-textiles) combine electronics and textiles to make wearable technologies that possess the characteristics of stretchability and conductivity. The focus of our research is to design stretchable interconnects for an e-textile bio-potential monitoring device that can withstand the strain imposed by various body movements. We fabricated silver conductive ink based S-curve interconnects using commercially available inks and 3D printing technology. Traces were printed on stretchable substrate material prior to lamination onto fabric. To determine the optimal interconnect shape, we focused on varying parameters such as trace length, trace width, peak amplitude height, and curve shape. Initial fabrication ("fabrication methodology 1") using a semi-sinterable silver conductive ink, "U" shaped arcs, print settings 1 and variable trace length rendered inconclusive results during the stretch versus resistance tests due to trace breakage. Modifications in the ink, print settings and arc shape were made to produce more durable prototypes. Modified fabrication ("fabrication methodology 2") using silver elastomeric ink, sine-wave shaped arcs and print settings 2 varied in terms of trace width, and peak amplitude height. The results of the stretch versus resistance test found that thicker traces with larger amplitude height rendered low initial resistance, small changes in resistance under strain, excellent recovery post-stretch and resilience to breakage. The findings of the paper will be used to aid in the fabrication of a surface electromyography (sEMG) garment for rehabilitative use in a healthcare setting.