Advanced SERS Platform for Uniform and Reliable Molecular Detection

Signal uniformity is crucial for reliable and quantifiable surface-enhanced Raman scattering (SERS) measurements. However, challenges arise due to the continuous impact of localized hottest spots and the coffee ring effect on signal uniformity. In response to this, we developed a platform featuring a hierarchical structure with Ag nanopores and microbowls (HANM) and incorporated superhydrophobic/superhydrophilic (SHB/SHL) treatments. This design enhances the hottest spot area, ensuring a strong and consistent electromagnetic field while mitigating the coffee ring effect, which leads to an even analyte distribution. This was demonstrated by analyzing rhodamine 6G (R6G, 4 μL, 10^-9 M to 10^-12 M) molecules at different concentrations. The 2D mapping of the SERS signal intensities from the entire dried droplet exhibited excellent uniformity. The relative standard deviation of the intensities from 200 randomly selected points was calculated to be just 3.81%, laying the foundation for the quantitative detection capability. Additionally, through bisphenol A (BPA) detection in water samples collected from five different locations, the HANM-SHB/SHL structure consistently detected BPA with a uniform signal intensity across all water samples. In conclusion, we proposed a dual-function SERS platform featuring an improved hottest spot region and the ability to avoid the coffee ring effect, offering precise and reliable molecular analysis.