Different number of silver nanoparticles layers for surface enhanced raman spectroscopy analysis

•SERS substrate with different Ag NPs layers was obtained with simple and easy-popularization way.•The SERS effects gradually become strong as the increasing number of Ag NPs layers.•The reproducibility of SERS substrates was significantly promoted as the Ag NPs layers increases.•The SERS substrate can easily combine with some other blocks with superior SERS property.•The 3D Ag NPs SERS substrate can be put into practical application easily.

For application in practice, reducing the cost and simplifying the steps in fabrication of SERS substrates with excellent property are still the important factors. Here, a three-dimensional (3D) Ag nanoparticles (NPs) obtained by facile thermal evaporation is obtained for SERS. The Raman enhancement effect gradually become strong as the number of Ag NPs layers increase and attain the best until four layers Ag NPs deposited for the finite penetration depth of incident laser. The intensity of Raman signal collected from the four-layer Ag NPs substrate is around 11.3 times stronger than that from one-layer Ag NPs. Besides, the reproducibility of the SERS substrate was also significantly promoted as the layers of Ag NPs increases. The SERS substrate exhibits temporal stability and its enhancement factor attains 6.8 × 108. Furthermore, the SERS substrate can easily combine with some other blocks with superior SERS property and show better SERS ability. Additionally, the in-situ trace analyses in aquatic products were realized by flexible Ag NPs/PET substrate.