Highly stretchable and sensitive SBS/Gr/CNTs fibers with hierarchical structure for strain sensors

• Hierarchical fiber with CNTs and graphene was fabricated by solution etching. • The sensing performance of strain sensor was greatly improved by solution etching. • The sensor has a gauge factor up to 1667 over a wide strain range from 0 to 500%. • Its working range was 31 times larger than that of the non-etched fiber based sensor. Most of the reported flexible strain sensors can only normally sense external stretch in a quite narrow working range and with low sensitivity. In order to overcome these drawbacks, elastomeric fiber based strain sensors incorporating graphene (Gr) and carbon nanotubes (CNTs) were initially fabricated via coaxial wet spinning. The solution etching method was employed for forming a 1D@2D@1D hierarchical structure, with pores and microcracks on fibers, to reconstruct their conductive networks. The solution etched fiber based strain sensors achieved a significant improvement in obtaining a high maximum gauge factor of 1667 and capability of working over a wide strain range (0-500%, approximately 31 times larger than that for the non-etched fiber). Furthermore, the strain sensor showed excellent durability over 10000 tensile strain cycles. Finally, the based strain sensor was used to monitor physiological movements such as finger, elbow and knee bending with fast and accurate responses.