The study introduces a spatiotemporal chromatography-mimicking (SCM) e-nose that integrates laser-tailored graphene paper with a microchamber for precise volatile organic compound (VOC) discrimination. The SCM e-nose overcomes traditional array limitations with a single multifunctional component capable of accurate VOC differentiation via chromatography-mimic features. Advanced laser-engraving techniques fabricate a gas-permeable interdigitated electrode from graphene paper as the sieving framework. Key achievements include its single multifunctional component, economical and scalable design, distinct response patterns for different VOCs, remarkable ability to discriminate mixed VOCs, versatility for diverse applications including real-time on-site analysis, and ease of integration with electronic systems. The SCM e-nose represents a significant advancement in electronic nose technology, offering a compact, cost-effective solution for precise VOC detection and analysis.
Mengyue Gao,Wei Fang,Jiaqiang Ren,Aiguo Shen,Jiming Hu
Nitrites (NO2− ions) in food and drink play an important role in human health but require complicated operations before detection. Herein, we present a rationally designed SERS-enabled micro-chamber that comprised a drawn glass capillary with a tiny orifice (∼50 μm) at the distal tip, wherein the gold nanoparticles (Au NPs) are compactly coated on the inner wall surface. In this chamber, nitrites specifically trigger a pH and laser irradiance-dependent diazotization starting from p-aminothiophenol (PATP) absorbed onto the surface of Au NPs to form p,p′-dimercaptoazobenzene (DMAB) molecules, in which the presence of NO2− ions above 30.7 μM (1.38 ppm) in the siphoned liquid sample can be identified relying on SERS peak (1141 cm−1) intensity of the emerging azo moiety. Except for pH conditions, laser irradiance is more important but easily neglected in previous studies, which is capable of preventing generation of errors when the detection sensitivity was pursued through increasing the laser power. In this case, several real samples (rather than simple water samples), including honey, pickled vegetable and fermented bean curd, had been successfully detected accurately through such a convenient sampling micro-chamber. The SERS-enabled device could potentially be facilely incorporated with portable Raman instruments for a special application of food inspection in rapid and field analysis of NO2− ions.
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