Island-bridge microcracks with nanofiber and carbon nanotube composites for high-performance flexible strain sensors

Abstract

Resistive flexible strain sensors have attracted widespread attention in the field of wearable bioelectronics due to their simple structure and low cost. In recent years, significant progress has been made in the fields of resistive flexible strain sensors with a wide sensing range and high sensitivity, however, their long-term durability in epidermal sensing applications remains a challenge. Common methods of constructing protective layers often lead to unavoidable interlayer interactions, which adversely affect both hysteresis and stability of the sensor. This paper reports a stretchable strain sensor with a Ravioli Pasta structure (RPS) via dual-electrospinning nanofibers and spraying carbon nanotubes, in which the sensing composites with an island-bridge microcrack structure is embedded within a nanofiber film. This design provides three-dimensional restoring forces to aid the healing of microcracks, minimizing the impact of interlayer interactions between the sensing and protective layers, as well as within the protective layer itself, on the sensor performance. In wearable device applications, the flexible strain sensor maintains fast response speed (24 ms) and excellent repeatability (∼12,000 cycles) under 50 % strain, with high sensitivity (GF = 37.38) and low hysteresis (γ = 3.568 %), and is successfully used for real-time physiological signal monitoring and robotic hand control.