Silver Nanoparticle Enhanced Antibacterial, Ultra-Broad Responsive κ-Carrageenan Composite Hydrogels for Flexible Strain Sensors

A multi-component hydrogel was prepared by the sol–gel process of anionic κ-carrageenan to construct a physical cross-linking network and chemical cross-linking of acrylamide (AM), in which polyvinylpyrrolidone (PVP) served as a component of the semi-interpenetrating network, and nano-silver powders were used as conductive particles and antibacterial agents of the hydrogel. XRD confirmed that the hydrogel contained silver nanoparticles, and the homogeneous dispersion of silver nanoparticles made the hydrogel have high conductivity (35.84 S/m) and also improved its sensitivity in strain response. The strain sensitivity gauge factor (GF) of the hydrogel could reach 6.79 in a relatively large strain range (100%–500%), and it also had a high response sensitivity in the weak strain range such as 0.1% to 5% (GF = 1.43). The presence of PVP-Ag improved the mechanical properties of the gel, and its tensile strength, elongation at break, and toughness were 0.345 MPa, 1310%, and 4519.5 kJ/m 3 , respectively. With the increase in carrageenan content, the thermal reversibility of the hydrogel was dominant, and the composite hydrogel behaved with a certain self-healing ability. Thus, this work could provide a flexible electronic material with biocompatibility, antibacterial properties, high sensitivity, and a wide strain range. Graphical The interaction mechanisms of each component of the prepared conductive hydrogel CG/PAM/PVP-Ag and its typical electrical responses for monitoring human breathing.