Transparent and Waterproof Ionic Liquid-Based Fibers for Highly Durable Multifunctional Sensors and Strain-Insensitive Stretchable Conductors.

Ionic liquids (ILs) are regarded as ideal components in the next generation of strain sensors because their ultralow modulus can commendably circumvent or manage the mechanical mismatch in traditional strain sensors. In addition to strain sensors, stretchable conductors with a strain-insensitive conductance are also indispensable in artificial systems for connecting and transporting electrons, similar to the function of blood vessels in the human body. In this work, two types of ILs-based conductive fibers were fabricated by developing hollow fibers with specific microscale channels, which were then filled with ILs. Typically, the ILs-based fiber with straight microchannels exhibited a high strain sensitivity and simultaneously rapid responses to strain, pressure, and temperature. The other ILs-based fiber with helical microchannels exhibited a good strain-isolate conductance under strain. Due to the high transparency of ILs along with the sealing process, the as-prepared ILs-based fibers are both highly transparent and waterproof. More importantly, owing to the low modulus of ILs and the core-shell structure, both conductive fiber prototypes demonstrated a high durability (>10 000 times) and a long-term stability (>4 months). Ultimately, the ILs-based fibrous sensors were successfully woven into gloves, flaunting the ability to detect human breathing patterns, sign language, hand gestures, and arm motions. The ILs-based strain-insensitive fibers were successfully applied in stretchable wires as well.