Modulation and Mechanisms of Cellulose‐Based Hydrogels for Flexible Sensors

Flexible sensors exhibit the properties of excellent shape adaptability and deformation ability, which have been applied for environmental monitoring, medical diagnostics, food safety, smart systems, and human–computer interaction. Cellulose‐based hydrogels are ideal materials for the fabrication of flexible sensors due to their unique three‐dimensional structure, renewability, ease of processing, biodegradability, modifiability, and good mechanical properties. This paper comprehensively reviews recent advances of cellulose‐based hydrogels in the construction of flexible sensor applications. The characteristics, mechanisms, and advantages of cellulose‐based hydrogels prepared by physical cross‐linking, chemical cross‐linking are respectively analyzed and summarized in detail. The focus then turns to the research and development in cellulose‐based hydrogel sensors, including physical sensing (pressure/strain, humidity/temperature, and optical sensing), chemical sensing (chromium, copper, and mercury ion sensing, toxic gas sensing, nitrite sensing), and biosensing (glucose, antibody, and cellular sensing). Additionally, the limitations of cellulose‐based hydrogels in sensors, along with key challenges and future directions, are discussed. It is anticipated that this review will furnish invaluable insight for the advancement of novel green, flexible sensors and facilitate the integration of cellulose‐based hydrogels as a fundamental component in the development of multifunctional sensing technologies, thereby expediting the design of innovative materials in the near future.