Multifunctional dual-crosslinked Ti3C2Tx MXene-based hydrogels for wearable sensors with enhanced mechanical robustness and broadband microwave absorption

The development of multifunctional hydrogels with enhanced mechanical, electrical, and electromagnetic properties has become a key focus in various advanced applications, including wearable electronics, strain sensors, and electromagnetic interference (EMI) shielding. However, challenges remain in achieving a balanced integration of stretchability, conductivity, and broadband microwave absorption within a single material. This study addresses these limitations by introducing a novel dual-crosslinked Ti3C2Tx MXene-based hydrogel designed for wearable sensor and EMI shielding applications. The PVA/MXene/PSS hydrogel is synthesized via a freeze-thaw crosslinking method to create a three-dimensional (3D) conductive network. Water retention and conductivity are enhanced through the synergistic effect between sodium chloride (NaCl) and formic acid (HCOOH), addressing key challenges such as water evaporation and MXene dispersion. The resulting hydrogel exhibits impressive mechanical stretchability (369% tensile strain), long-term stability (6000 s under 25% strain), and ultra-high strain sensitivity with a minimum detectable strain of 1%. It demonstrates gauge factors of 0.78 and 0.51 in the transverse and longitudinal directions for strains below 50%, respectively, and 0.28 and 0.37 for strains between 50% and 100%. Moreover, it demonstrates exceptional broadband microwave absorption with a peak reflection loss of -55.5 dB at 10.73 GHz and an effective absorption bandwidth of 6.34 GHz. The combination of excellent mechanical, electrical, and microwave properties, along with superior stretchability and durability, makes this hydrogel a promising candidate for next-generation wearable sensors, flexible electronics, and electromagnetic interference shielding.