Conductive Polyvinyl Alcohol-Based Hydrogels for Wearable Electronics: Preparation Strategies, Conductivity Enhancement, and Sensing Applications

Conductive poly(vinyl alcohol) (PVA)-based hydrogels combine electrical functionality with the mechanical compliance and biocompatibility required for wearable bioelectronics. However, simultaneously achieving mechanical robustness, stable electrical conductivity, and long-term hydration stability remains challenging. Adopting a performance trade-off perspective focused on wearable sensing, this review examines recent advances in five interconnected areas: (1) fabrication strategies, including freeze–thaw cycling, the Hofmeister effect, mechanical training, and green synthesis routes; (2) conductivity enhancement through electron-conducting pathways (carbon nanofillers, MXene, and conducting polymers), ionic routes (salt and electrolyte doping), and hybrid systems; (3) wearable sensing applications, including physiological monitoring (ECG/EMG/EEG), multimodal biosensing of biofluid analytes, and intelligent sensing devices; (4) environmental resilience and mechanical durability; and (5) regulatory, manufacturing, and clinical translation challenges. Representative studies report tensile strengths exceeding 19 MPa, electrical conductivities above 10 S/m, gauge factors above 10, and self-healing within 1 s; however, these values were obtained for different formulations and under different testing conditions. The review further identifies critical gaps in reproducibility, comparable testing protocols, device-level integration, and scalability, and outlines design considerations for advancing conductive PVA-based hydrogels toward reliable wearable health monitoring systems.