An Autofluorescent Hydrogel with Water‐Dependent Emission for Dehydration‐Visualizable Smart Wearable Electronics

Abstract Wearable flexible electronics that are derived from hydrogels inevitably undergo dehydration, and the sensing performance is highly affected because the stretchability and conductivity weaken. Monitoring the water retention rate of hydrogels as they operate without dismantling the assembled sensing device is vital for evaluating sensing performances and intervening in a timely manner to address the problem. However, relevant research is still lacking. Herein, an autofluorescent hydrogel is engineered based on clusterization‐triggered emission (CTE) for wearable strain‐sensing electronics that can undergo self‐visualizing dehydration. The fluorescence intensity of the CTE‐type autofluorescent hydrogel depends on the aggregation level of molecule clusters that are dangled on the gel networks, which is dominated by the water retention rate of the hydrogel. Thus, the dehydration process can be reflected by the fluorescent images taken in a scenario of long‐term strain‐sensing. This strategy helps the operator evaluate the water retention rate of the hydrogel without removing it from the assembled electronics and then quickly address the problem. In addition, this strategy is also applicable for dehydration‐tolerant systems, demonstrating the versatility of the autofluorescent hydrogel. Overall, the CTE‐type autofluorescent hydrogel will promote the development of high‐performance and smart wearable electronics.