An MXene-doped PVA/PVP hydrogel-based strain sensor applicable in liquid environment

Hydrogel-based strain sensors garner immense interest in view of their excellent mechanical properties and sensing performance for applications in a liquid environment. However, swelling of hydrogel in liquid would significantly degrade its electro-mechanical performance. This work presents a new fabrication method for an anti-swellable hydrogel synthesized by mixing titanium carbide (Ti3C2T (x) ) MXene nanoparticles with polyvinyl alcohol (PVA) and polyvinylpyrrolidone (PVP) blend. A strong interaction can be formed between the double-network PVA/PVP hydrogel matrixes through a cyclic freezing-thawing method, and the addition of the MXene further improves the electro-mechanical properties of the hydrogel. Our results reveal that the synthesized MXene-PVA/PVP hydrogel (MX-hydrogel) improves the gauge factor of the sensor by 61% compared to that of a hydrogel without adding MXene nanoparticles when applied as a strain sensor. Moreover, the MX-hydrogel formed in its recovery stage exhibits a volume-limited swelling, which can be regarded as anti-swellable behavior. Finally, the synthesized MX-hydrogel's structural, elastic, thermal, and electrical properties are investigated, paving the way toward dosage monitoring as a demonstration of the application.