Fluorescent Hydrogel-Coated Paper/Textile as Flexible Chemosensor for Visual and Wearable Mercury(II) Detection

In some industrial districts, abuse discharge of waste water has resulted in serious Hg2+ pollution in seafood, grain, and even drinking water. In order to protect people from mercury(II)-polluted food and water, many solid-state fluorescent Hg2+-sensing materials are developed in terms of facile operation. However, one primary challenging issue is the restricted sensitivity caused by hindered slow diffusion of aqueous testing samples inside these conventional hydrophobic, dense, and rigid film materials. Herein, robust hydrophilic fluorescent hydrogel-coated flexible paper/textile film chemosensors are reported. Their design relies on a specific chemical reaction between Hg2+ and the grafted thiourea moieties to induce remarkable green-to-blue emission color change. Thanks to their hierarchical porous structures fixed by interwoven paper/textile fibers, these flexible chemosensors allow fast capillary-force-driven mercury(II) diffusion into the hydrophilic hydrogel matrix, thus enabling visual detection of nearly nM-level Hg2+. On this basis, robust fluorescent hydrogel-coated wearable sensing gloves are fabricated for the first time, which significantly facilitate infield visual detection and effectively protect operators far from the toxic Hg2+-polluted samples. These developed flexible wearable sensing systems might not only hold great potential applications in mercury(II) detection, but also inspire the development of next-generation sensing apparatus for other food and environmental pollutants.