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.
Photonic barcodes with random fingerprints possess significant potential applications in anti-counterfeiting and security protection due to their unclonable characteristics. Here, a scalable coding strategy is proposed to realize the physical unclonable function (PUF) codes based on a random-distributed biconcave-cavity random laser (BCRL) array in microchannel . Its unique configuration exhibits scalable randomness induced by microcavities and the scatterers , demonstrating a PUF characteristics in lasing intensity variations with pump positions. The random intensity information is firstly used as 1st-order coding to generate the PUF codes. The CIE tristimulus values of the tricolor lasing is then established as 2nd-order coding. The obtained codes strongly rely on the relative position of the arrays, indicating excellent unclonability and high generation efficiency. This work supplies a low-cost way to generate PUF codes for security system, promoting random lasing applications in security protection.
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