Printed Stretchable\nGraphene Conductors for Wearable\nTechnology

Abstract

Skin-compatible printed stretchable conductors that combine\na low\ngauge factor with a high durability over many strain cycles are still\na great challenge. Here, a graphene nanoplatelet-based colloidal ink\nutilizing a skin-compatible thermoplastic polyurethane (TPU) binder\nwith adjustable rheology is developed. Stretchable conductors that\nremain conductive even under 100% strain and demonstrate high fatigue\nresistance to cyclic strains of 20–50% are realized via printing\non TPU. The sheet resistances of these conductors after drying at\n120 °C are as low as 34 Ω □^–1 mil^–1. Furthermore, photonic annealing at several energy\nlevels is used to decrease the sheet resistance to <10 Ω\n□^–1 mil^–1, with stretchability\nand fatigue resistance being preserved and tunable. The high conductivity,\nstretchability, and cyclic stability of printed tracks having excellent\nfeature definition in combination with scalable ink production and\nadjustable rheology bring the high-volume manufacturing of stretchable\nwearables into scope.