Highly conductive and stretchable fiber interconnections using dry-spun carbon nanotube fibers modified with ionic liquid/poly(vinylidene fluoride) copolymer composite

In this paper, we demonstrate highly conductive and stretchable fiber interconnections for electronic textiles (e-textiles) using dry-spun carbon nanotube (CNT) fibers modified with ionic liquid (IL)/poly (vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP) copolymer composite. By adopting direct infiltration of CNT fibers with a mixture of 1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide and PVDF-HFP, mechanical properties such as stretchability, maximum load and strain were significantly improved while minimizing the reduction in electrical conductivity. Such IL/PVDF modified CNT fibers (hybrid CNT fibers) exhibited electrical conductivity up to ∼1300 S/cm, with maximum load and strain values of 0.84 N and 35.7%, respectively. Using hybrid-CNT fibers, we demonstrated highly stretchable and electrically stable fiber interconnections for e-textiles by optimizing the interconnection pattern design. Particularly, by adopting a serpentine pattern, stretchability up to ∼70% and resistance variation of ∼2.7% at a tensile strain of 40% were achieved.