Ag microlabyrinth/nanoparticles coated large-area thin PDMS films as flexible and transparent SERS substrates for in situ detection

Flexible and transparent surface-enhanced Raman scattering (SERS) substrates have attracted much attention as a fast, sensitive and in situ detection platform for practical applications. However, the large-area fabrication of flexible and transparent SERS substrates with high performance is still challenging. Here, a flexible and transparent SERS substrate based on large-area thin PDMS film decorated with Ag microlabyrinth/nanoparticles hierarchical structures (denoted as [email protected]) is fabricated by using the floating-on-water method and magnetron sputtering technology. By optimizing the sputtering time, the ALNHS with multiple hot spots are uniformly distributed on the PDMS surface. Based on characterizing the rhodamine 6G (R6G) with a portable Raman spectrometer, the optimal [email protected] film exhibits a high enhancement factor (5.2×106), excellent uniformity and reproducibility, as well as superior mechanical stability. In addition, thanks to the good sticky feature and bi-directional activation property of the thin [email protected] film, the prepared flexible and transparent SERS substrate can achieve in situ detection of malachite green residues (10-6 M) on apple and tomato skins. This large-area, thin, mechanically robust, flexible and transparent [email protected] film, integrated with a portable Raman spectrometer, shows great potential for point-of-care testing (POCT) in practical applications.