Recent progress of biomaterials-based hydrogels for wearable electronics and health monitoring

Soft bioelectronics integrated with biological tissues are reshaping the landscape of personalized medicine, health diagnostics, and human-machine interfaces, yet they are frequently bottlenecked by the mechanical and biocompatibility discrepancies of conventional rigid hardware. Biomaterials-based hydrogels, defined as hydrogel systems constructed from natural polysaccharide or protein macromolecules, featuring extracellular matrix-like compliance, well-documented biocompatibility in numerous prior biomaterial studies and abundant functional groups, have emerged as promising interfacial materials to bridge this mechanical and biological mismatch. This review comprehensively surveys the state-of-the-art developments in polysaccharide-based (alginate, chitosan, and cellulose) and protein-based (collagen, silk fibroin, and bovine serum albumin) hydrogel platforms. It also analyzes their internal structures, crosslinking network topologies, and approaches to mechanical property regulation. Additionally, the deployment of these engineered hydrogels in capturing high-purity electrophysiological signals (e.g., electroencephalograms (EEG), electrocardiograms (ECG), and electromyograms (EMG)), as well as conducting respiratory monitoring and motion monitoring, is systematically evaluated. This review highlights critical structure-property trade-offs: reconciling mechanical softness, conductivity, biocompatibility and environmental stability remains a major unsolved bottleneck. In closing, the review concludes major contemporary challenges and future research routes for robust long-term wearable and implantable bioelectronics, to motivate original material designs of advanced soft biointerfaces for both wearable epidermal and implantable bioelectronic scenarios.