Environmental Stability Stretchable Organic Hydrogel Humidity Sensor for Respiratory Monitoring with Ultrahigh Sensitivity

Abstract Real‐time monitoring of respiration plays a very important role in human health assessment, especially in monitoring and analyzing respiration during exercise and sleep. However, traditional humidity sensors still have problems in flexibility, sensitivity, and durability, so there is an urgent need to develop humidity sensors with high sensitivity, stretchability, and environmental resistance as respiratory monitoring applications. Here, based on the double network hydrogel structure of polyvinyl alcohol and polyacrylamide, a highly sensitive, highly stretchable, and environmentally stable organic hydrogel humidity sensor has been manufactured by using the synergistic effect of lithium chloride and MXene. The hydrogel humidity sensor shows rapid response in the humidity range of 40–85% RH, and has a high sensitivity of −103.4%/% RH. In addition, it exhibits more than 3000% mechanical strain and excellent environmental resistance, which is attributed to the chemical cross‐linking in the hydrogel network and the synergistic effect of multiple hydroxyl groups in glycerol forming rich hydrogen bonds with water and polymer chains. The hydrogel humidity sensor is used for real‐time monitoring of breathing and sleep processes. This work provides a new strategy for preparing high‐performance, extensibility, and environmental stability hydrogel‐based sensors for respiratory monitoring.