Breathable, durable, and ultrathin ionogel fiber sensors for strain and temperature sensing based on TPU and few-layer black phosphorus

Conductive ionogels are emerging materials for next-generation sensing systems in flexible electronics. However, fabricating conductive ionogels with the ideal combination of stretchability, breathability, comfort, and multi-sensing capabilities remains a significant challenge. In this study, we developed fibrous films of an ionogel-based nanofiber composite incorporating ionic liquid (IL), polyurethane (TPU), and few-layer black phosphorus (BP) using electrospinning. The synergistic effects of dipole-dipole interactions and physical entanglement in these nanofiber films resulted in high tensile strength (16.91 MPa), strong elasticity, and excellent air permeability (200.60 g m⁻², 24 h). The incorporation of BP significantly enhanced the sensitivity of the films, as indicated by the increase in gauge factor (GF) from 1.37 to 3.87. Furthermore, these films demonstrated excellent sensing stability and efficient temperature sensing, attributed to the negative temperature coefficient of IL. These properties enable the films to accurately detect human activities under ambient conditions, offering promising applications in flexible smart electronics.