Strong and tough PVA/PAA hydrogel fiber with highly strain sensitivity enabled by coating MWCNTs

A super strong poly (vinyl alcohol)/poly (acrylic acid) (PVA/PAA) anti-freezing hydrogel fiber has been successfully constructed and studied. The introduction of PVA chains significantly improves tensile strength and toughness to 3.8 MPa and 13.7 MJ/m 3 , respectively. In addition, glycerol in the hydrogel fiber ensures its good flexibility even in −15 °C. We coat hydrogel fiber with multi-walled carbon nanotubes (MWCNTs) and study their strain sensing properties. The composite hydrogel fiber has a high gauge factor of 25 at the strain of 40%, which is superior to those common hydrogel-based strain sensors. Notably, the composite hydrogel fiber shows a high stability and repeatability of 5000 cycles, and a fast response time of 225 ms. Besides, the composite hydrogel fiber can detect the large and subtle body movements accurately and timely. Therefore, this composite hydrogel fiber may be a very hopeful candidate for wearable sensing devices.