Multifunctional MXene-Enhanced, Phase-Separated Dual-Network Hydrogel for Linear Wide-Range Strain Sensing in Wearable Electronics

Abstract

Accurate detection of both subtle and large deformations remains a major challenge for hydrogel-based wearable strain sensors. Here, we report a multifunctional phase-separated hydrogel composed of polyacrylamide (PAM), sodium alginate (SA), polyurethane (PU), and MXene nanosheets. The phase-separated microstructure and MXene-mediated conductive pathways synergistically enhance the mechanical performance and strain-responsive electrical behavior of the hydrogel. The optimized formulation exhibits a Young’s modulus of approximately 4.5 kPa and a strain at break of approximately 750%. It also demonstrates strong self-adhesion to various substrates and rapid restoration of electrical conductivity after cutting and recontacting. The resulting strain sensor delivers a stable electrical response over a broad strain range of 1−450%, with an approximately linear response between 30% and 450%, a gauge factor of approximately 1.08, and a response time of 0.4 s. The sensor maintains reproducible sensing performance over 200 loading−unloading cycles and enables the monitoring of both large joint movements and subtle physiological signals, including radial artery pulsation. In vitro assays using L929 fibroblasts and HaCaT keratinocytes indicate acceptable preliminary cytocompatibility. In addition, the synthesized hydrogel exhibits a low hemolysis rate and minimal skin sensitization potential, further supporting its biosafety and potential for direct skin-contact applications. Overall, this study presents an effective strategy for integrating phase-separated microstructures and MXene-based conductive pathways into mechanically robust and biocompatible hydrogels for wearable sensing and human−machine interface applications.