Multiscale Wrinkled Microstructures for Piezoresistive Fibers

Even though flexible piezoresistive materials are widely researched in recent years, it is full of challenges to simultaneously satisfy high conductivity, stretchability, and sensitivity. In this study, core-shell conductive fibers with high conductivity (10(-4)-10(-5) Omega cm), stretchability (400%), and durability (more than 1200 s ultrasonic treatment) are presented and multiscale wrinkled microstructures (about 1.7 mu m in height and 2.6 mu m in length) are built on the surfaces of fibers via simply writing silver nanowires ink on prestrained commercial polyurethane fibers. The as prepared core-shell elastic fibers are twisted to construct flexible piezoresistive fibers, which show desirable sensitivity to pressure and bending deformations (0.12 kPa(-1) and 0.012 Rad(-1)), fast response and relaxation time (35 and 15 ms), very low detection limit (10 mg), and excellent working stability (>4000 loading/unloading cycles). The wrinkled microstructures to overcome the viscoelastic delay of polymer composites are observed, making substantial contributions to improve the responsiveness. The investigations to the sensing mechanism indicate that increasing the contact points inner the flexible piezoresistive fibers will significantly improve the sensitivity. Finally, the potential applications of the flexible piezoresistive fibers as wearable devices and smart fabrics are demonstrated.