Conductive Hydrogels for Wearable Sensing: Materials, Mechanics, and Multimodal Interfaces

Conductive hydrogels combine tissue conformability, conductivity, and biocompatibility, making them an emerging class of materials for soft and wearable bioelectronics applications. This review comprehensively presents the latest developments in studies of conductive hydrogels for wearable sensing applications, including materials chemistry, mass and charge transport physics, and device engineering. Starting with an examination of the main materials used, such as conducting-polymer networks, nanocomposites, and ionic hydrogels, we analyze how molecular network design, hydration state, and conducting-phase organization jointly determine the electromechanical performance and durability of devices. We discuss how microscopic mechanisms related to mechanical behavior, transport phenomena under deformation, and the influence of viscoelasticity on conductivity as a function of hydration degree are linked to the macroscopic response of devices. The review discusses how strain, pressure, temperature, and multimodal sensing are detected as a function of the device architecture and its transduction mechanisms. Aspects related to interface engineering, skin adhesion, long-term reliability, and the development of metrological frameworks necessary for comparison between different studies in the literature are explored. The latest developments in sustainability, biodegradability, and AI-assisted materials design are also presented. By integrating these analyses, the review suggests design principles and performance maps that can be used for the development of next-generation CH-based wearable devices that optimize mechanical softness, multimodal sensing capability, and environmental durability.