Hydrogel-based flexible sensors: from manufacturing strategies to sensing applications

Hydrogel-based flexible sensors combine tissue-like mechanical properties with superior sensing performance, showing immense potential in human–machine interactions, soft robotics, and health monitoring. Although significant progress has been made in related research, the fabrication of precise structures, the environmental tolerance of materials, and the heterogeneous integration between materials and devices remain key research challenges. In response to these challenges, this review provides a comprehensive review of the latest progress in hydrogel-based sensors, covering the entire process from material fabrication and functional regulation to interface engineering. First, the impacts of advanced processing techniques such as solution processing, microstructure molding, photolithography, additive manufacturing, and fiber spinning on film structure are discussed in detail. Subsequently, physicochemical strategies for enhancing sensing performance and environmental tolerance are analyzed. Furthermore, diverse assembly schemes and interface engineering strategies are highlighted. Finally, typical applications in pressure, strain, environmental, and physiological signal monitoring are summarized. This review aims to provide guidance for the development of next-generation high-performance and stable flexible electronic systems.