1：Experimental Design and Method Selection:

The study employed a lithography-free two-step process involving maskless plasma etching of polyethylene terephthalate (PET) to create nanopillars, followed by thermal evaporation of Ag to form plasmonic nanostructures. Surface tension-driven assembly was used to create nanogaps, and encapsulation with polydimethylsiloxane (PDMS) membranes was applied for molecular selectivity. Theoretical models included localized surface plasmon resonance (LSPR) and capillary force effects.

2：Sample Selection and Data Sources:

Samples included PET films for nanopillar fabrication, Ag for plasmonic structures, and PDMS for encapsulation. Test molecules were methylene blue (MB) and rhodamine 6G (R6G) dissolved in chloroform or deionized water, selected based on molecular weight and solubility.

3：List of Experimental Equipment and Materials:

Equipment included a custom-built RF ion etching instrument, thermal evaporation system, atomic layer deposition system, optical microscope, spectrometers, Raman microscope, FE-SEM, and TEM. Materials included PET, Ag, ZnO, PDMS (Sylgard 184), DEZ, DI water, MB, R6G, and chloroform.

4：Experimental Procedures and Operational Workflow:

Fabrication involved plasma etching of PET, Ag deposition, optional ZnO coating via ALD, PDMS encapsulation, and surface tension-induced leaning. Characterization included dark-field imaging, reflectance spectroscopy, Raman measurements, and electron microscopy. Testing involved dipping encapsulated substrates in analyte solutions and measuring SERS signals.

5：Data Analysis Methods:

Data analysis included calculation of SERS enhancement factors, comparison of reflectance spectra, and interpretation of Raman spectra to assess molecular selectivity and detection performance.