Interfacial modification strategy for the fabrication of high performance fiber-based strain sensors

Lightweight, stretchable, and wearable fiber strain sensors have recently been widely studied for the development of health monitoring systems, human-machine interfaces, and wearable devices. The interface interaction between the stretchable substrate and conducting materials plays a vital role in the performance of the fiber-based strain sensors. In this work, a scalable strategy using elastic yarn as a flexible substrate coated with a one-dimensional (1D) multiwalled carbon nanotube (MWCNT) and two-dimensional (2D) MXene (Ti3C2Tx) mixed conductive layer was presented. The introduction of ultra-thin polyurethane (PU) bridge layer into the sensing system greatly improved the interfacial adhesion between the yarn and conductive layer. Therefore, the sensors obtained significantly enhanced performance, which exhibited the superstretchability up to 300% without evidently irreversible damaging the intrinsic conductive pathways (the maximum elongation reached 1218%), high sensitivity (maximum gauge factor is approximately 441.68 at 210%–300%), fast response time (about 70 ms), and excellent stability (low fatigue properties over 1500 stretch-release cycles). Furthermore, the fabricated fiber strain sensors were used to access the relevant physiological signals, including finger and joint movements, face gestures, and sitting posture detection. Such high mechanical performance fiber-based electronics can serve as the basis for future multifunctional smart wearable sensors for abundant existing and emerging applications.