Hybrid Water-Harvesting Channels Delivering Wide-Range and Supersensitive Passive Fluorescence Humidity Sensors

The development of optical humidity detection has been of considerable interest in highly integrated wearable electronics and packaged equipment. However, improving their capacities for color recognition at ultralow humidity and response-recovery rate remains a significant challenge. Herein, we propose a type of hybrid water-harvesting channel to construct brand-new passive fluorescence humidity sensors (PFHSs). Specifically, the hybrid water-harvesting channels involve porous metal-organic frameworks and a hydrophilic poly(acrylic acid) network that can capture water vapors from the ambient environment even at ultralow humidity, into which polar-responsive aggregation-induced emission molecules are doped to impart humidity-sensitive luminescence colors. As a result, the PFHSs exhibit clearly defined fluorescence signals within 0-98% RH coupling with desirable performances such as a fast response rate, precise quantitative feedback, and durable reversibility. Given the flexible processability of this system, we further upgrade the porous structure via electrostatic spinning to furnish a kind of Nano-PFHSs, demonstrating an impressive response time (<100 ms). Finally, we validate the promising applications of these sensors in electronic humidity monitoring and successfully fabricate a portable and rapid humidity indicator card.