Multifunctional Integration of Hydrogel‐Based Sensors and Their Applications in Fire Early Warning Systems

Hydrogels are a class of hydrophilic materials that have the characteristics of a three‐dimensional polymeric network structure. They possess excellent flexibility, tunable hydration capacity, and responsiveness to external stimuli such as temperature, humidity, gases, and mechanical strain, making them highly promising for sensor applications. Owing to their favorable biocompatibility, stretchability, and electrical conductivity, hydrogels have emerged as key materials for multifunctional sensors, with wide‐ranging applications in wearable electronics, environmental monitoring, and intelligent healthcare systems. This review summarizes recent advancements in hydrogel‐based sensors for monitoring various stimuli, including temperature, humidity, gases, and strain, with particular emphasis on their development for fire detection and early warning. The self‐healing ability, adhesiveness, and compatibility of hydrogels with other functional materials, such as nanomaterials, metal ions, and metal–organic frameworks, have significantly enhanced both sensing performance and environmental adaptability. Nevertheless, challenges remain for hydrogel‐based fire sensors, particularly in terms of long‐term stability and interfacial adhesion. This article also outlines the prospective applications of hydrogel sensors in smart wearables, environmental sensing, and medical health monitoring, and proposes strategic solutions to current technical barriers. Finally, we discuss ongoing challenges, research directions, and future trends in the development of hydrogel fire sensors.