Highly robust skin collagen fiber network-reinforced multifunctional conductive hydrogel for multimodal sensing and TENG applications.

Against the backdrop of the rapid development of flexible wearable electronics and health monitoring technologies, conductive hydrogels, as the core functional materials for flexible sensors, have emerged as a research hotspot in this field by virtue of their skin-adaptive flexibility, excellent biocompatibility and unique ionic conductivity matching human skin. However, traditional conductive hydrogels suffer from critical bottlenecks such as poor mechanical strength, single functionality and reliance on external power supply, which severely restrict the expansion of their practical application scenarios. In this study, a novel multifunctional conductive hydrogel (called XMHAG) was successfully prepared through an innovative approach in which the natural collagen fiber 3D network structure of tanned sheepskin was adopted as the supporting framework and the precursor containing 2-hydroxyethyl acrylate (HEA), silver nanoparticles (AgNPs) and glycerol was integrated into the substrate, followed by the in situ polymerization of HEA in the gaps of collagen fibers. XMHAG exhibited outstanding comprehensive performance with a tensile strength as high as 36.41 MPa, a light transmittance of 72.5% and an elongation at break of 49%, while simultaneously integrating excellent toughness, antibacterial activity, environmental stability, anti-freezing and moisturizing properties and biocompatibility, which can meet the application requirements of flexible sensors in most complex scenarios. Benefiting from its efficient internal ionic conduction pathways, XMHAG exhibited a stable gauge factor (GF = 0.84) and ultrahigh sensing sensitivity, with a strain response time as low as 0.3 s and a recovery time of only 0.1 s. In terms of sensing functions, XMHAG could accurately identify human motion signals of different amplitudes, realize the efficient conversion of pressure signals into electrical signals during writing, providing core support for intelligent writing monitoring and interactive technologies, and capture human physiological electrical signals including electrocardiogram and electromyogram signals, offering a reliable technical solution for cardiovascular health monitoring and muscle function assessment. More importantly, XMHAG can be directly used as a flexible electrode and a triboelectric layer to support the construction of single-electrode triboelectric nanogenerators, enabling the efficient transformation of mechanical energy into electrical energy and fundamentally solving the problem of traditional flexible sensors relying on external power supplies. This study successfully overcomes the core technical bottlenecks in the synergistic optimization of mechanical strength enhancement and multifunctional integration for conductive hydrogels, and it is expected to drive the leaping iteration of flexible wearable electronic devices toward high stability, multifunctionality and self-powering and offer important material support and technical guarantee for technological innovation in fields such as health monitoring and intelligent interaction.