Spray‐n‐Sense: Sprayable Nanofibers for On‐Site Chemical Sensing

Abstract

A versatile "Spray-n-Sense" sprayable nanofiber technology for on-site chemical detection is demonstrated. Driven by compressed gas, the "Sprayn-Sense" nanofibers, as the name suggests, can be directly sprayed onto any kind or shape of surfaces, while the embedded chemical reporter enables simple colorimetric/fluorometric detection. Herein, nanofibers are sprayed on several surfaces including cardboard, glass, plastic, and rubber. The sensing capabilities of the "Spray-n-Sense" nanofibers are established through the detection of three different analytes including two metal ions (Fe 2+ and Fe 3+ using 1,10-phenanthroline and curcumin as chromogenic reporters, respectively) and ammonia (using rhodamine-B as a fluorogenic reporter) in aqueous media. Additional to being highly portable, the "Spray-n-Sense" nanofibers show impressive sensor characteristics with a sub-ppm lower limit of detection (LLOD) for Fe 2+ and a wide linear working range. Whereas, the LLOD of 6.2 and 32 ppm is achieved for Fe 3+ ions and ammonia, respectively. A custom-designed smartphone application enables quantitative analysis for reliable on-site sensing. The selectivity and specificity are imparted by the embedded reporter, and thus allow analyte detection in complex real-life samples and simultaneous detection of multiple chemical species through co-doping. The "Spray-n-Sense" nanofibers also allow for the detection of target analytes in solid samples.

Competitive Delocalized Charge Transfer Boosted by Solvent Induction Strategy for Survivable Colorimetric Detection of ng-Level Urea

“…One is the long-term stability of the probe would face challenges from the liquid environment resulted undesired activity, and the other is the inevitable transport and diffusion of either the solid analyte or the reaction product would cause a fatal dilution of the limited color signal. In terms of the above issues, various mediums have been investigated, such as paper strips, , fibrous membranes, , hydrogels, − and so on, mainly focusing on solving the second challenge. However, no matter what kind of materials or technologies applied for solid–liquid type sensing, remarkably fundamental and crucial role of solvent should not be neglected.…”