In this study, we developed a flexible and transparent silver/polystyrene/polydimethylsiloxane (Ag/PS/PDMS) substrate with both high density of hot spots and satisfactory uniformity using a cost-effective approach. Via template-guided self-assembly, PS beads were arranged regularly in nanobowls of a square array on PDMS, whose surface structure was transferred from a commercial CMOS chip. Roughness was introduced onto the PS bead surface by nitrogen plasma treatment, followed by sputtering of Ag which generated many hot spots. Differential roughness on the PS bead surface greatly influenced the morphology of the Ag/PS/PDMS substrate. A meat-ball like surface structure was formed with a plasma etching time of 5 min, whose growth mechanism was proposed based on the SEM analysis. The high sensitivity and desirable uniformity of the meat-ball like Ag/PS/PDMS substrate were demonstrated by using crystal violet (CV) as a Raman reporter, exhibiting an enhancement factor (EF) of 2.7×107 and a relative standard deviation (RSD) of 5.04%. Thiram of a lower concentration than the maximum residue limit (MRL) on the cucumber surface could easily be detected in-situ by the proposed substrate, demonstrating its great potential for in-situ food safety analysis.

In this paper, flexible and transparent surface-enhanced Raman scattering (SERS) substrate was prepared. First, silver nanoparticles (Ag NPs) were adsorbed onto 2D stretched polydimethylsiloxane (PDMS) and then the stretch was released and nanowrinkles were formed, bringing the adsorbed Ag NPs close to each other. SERS measurement demonstrated really high sensitivity of the Ag/PDMS substrate fabricated under 30% deformation and 120 min assembling time, the enhancement factor (EF) of which was estimated to be [Formula: see text]. SERS mapping analysis revealed the proposed Ag/PDMS substrate possessed excellent uniformity with relative standard deviation (RSD) of as low as 5.62%. For real-life applications, the versatile Ag/PDMS substrate could be used for both solution detection and in situ detection of solid objects of any shape. Tricyclazole, a commonly used pesticide, might pollute the leaves of crop and even remain in milk, endangering human health. Therefore, there is practical demand for developing direct on-site detection methods. In this paper, tricyclazole of 10[Formula: see text] M was easily probed by dropping the contaminated milk solution on the proposed substrate and 10[Formula: see text][Formula: see text]M tricyclazole sprayed on a leaf exhibited clearly identifiable Raman signals after attaching the proposed substrate to the leaf surface, demonstrating the prepared high-sensitive Ag/PDMS substrate is a competitive tool for rapid, trace and in situ detection.