Flexible, transparent and highly sensitive SERS substrates with cross-nanoporous structures for fast on-site detection

Abstract

A flexible and transparent film assembled from the cross-nanoporous structures of Au on PET (CNS of Au@PET) is developed as a versatile and effective SERS substrate for rapid, on-site trace analysis with high sensitivity. The fabrication of the CNS of Au can be achieved on a large scale at low cost by employing an etching process with super-aligned carbon nanotubes as a mask, followed by metal deposition. A strongly enhanced Raman signal with good uniformity can be obtained, which is attributed to the excitation of "hot spots" around the metal nanogaps and sharp edges. Using the CNS of Au@PET film as a SERS platform, real-time and on-site SERS detection of the food contaminant crystal violet (CV) is achieved, with a detection limit of CV solution on a tomato skin of 10-7 M. Owing to its ability to efficiently extract trace analytes, the resulting substrate also achieves detection of 4-ATP contaminants and thiram pesticides by swabbing the skin of an apple. A SERS detection signal for 4-ATP has a relative standard deviation of less than 10%, revealing the excellent reproducibility of the substrate. The flexible, transparent and highly sensitive substrates fabricated using this simple and cost-effective strategy are promising for practical application in rapid, on-site SERS-based detection.

Large‐Scale Sub‐1‐nm Random Gaps Approaching the Quantum Upper Limit for Quantitative Chemical Sensing

“…But the uniformity performance of the high‐density nanogap structure is still better than many nanopatterns including those periodic nanostructures fabricated by expensive top‐down lithography processes (e.g., refs. [ 42,49–57 ] as shown in Figure 3f). This uniform response enables quantitative sensing of molecules, which is considered as one of the major challenges for practical SERS sensing applications.…”

“…f) Direct comparison of SERS signal uniformity obtained by previously reported nanostructures (data from refs. [ 42,49–57 ] ) and the nanogap structures with molecule ii under different objective lenses.…”

Multifunctional Skin‐Inspired Flexible Sensor Systems for Wearable Electronics

“…Among them, the in situ SERS detection based on the flexible substrates is considered as the most promising approach, which is performed by first conformally attaching the flexible SERS substrates onto objective surfaces of interest, followed by the excitation of incident photons and collection of Raman signals from the back side of the SERS substrates. Until now, a diversity of flexible substrates have been applied for in‐situ SERS detection, such as PDMS, PMMA, polyethylene terephthalate (PET), polyethylene (PE), poly(vinylpyrrolidone) (PVP), paper, adhesive tape, as well as nanowires . The conventional methods to prepare active nanostructures on flexible and transparent substrates rely on depositing nanoparticles by physical or chemical routes.…”

Spot‐on SERS Detection of Biomolecules with Laser‐Patterned Dot Arrays of Assembled Silver Nanowires

“…However additional aspects shall be considered when dealing with daily life applications. These include low production costs, fabrication methods suitable for high volume manufacturing, reduced training times and skills needed for their routine usage, integration potential with portable Raman systems for on site applications, simple reusage or disposable characteristics and quick processing of a variety of samples …”

“…These include low production costs, fabrication methods suitable for high volume manufacturing, reduced training times and skills needed for their routine usage, integration potential with portable Raman systems for on site applications, simple reusage or disposable characteristics and quick processing of a variety of samples. [4][5][6][7] The above considerations hold particular significance when life science and healthcare applications of SERS are concerned, [8,9] whose primary conditions are high-throughput, multisample and inexpensive analyses at reduced costs. [10,11] According to this picture, in the last decade a great deal of efforts has been exerted in the development of functional SERS substrates obtained by simple, low cost, rapid and scalable fabrication methods, such as micropipetting, screen-and ink-jet printing, and filtration of colloidal solutions of plasmonic nanoparticles.…”