Fig. 2: Characterizations of the Ag nanomushroom arrays as a SERS substrate.
a Scanning electron microscope (SEM) image of Si nanopillar arrays fabricated by template-assisted ion etching techniques. b SEM and c atomic force microscope (AFM) images of Ag nanomushroom arrays after deposition of Ag layer on Si nanopillar. d FEA and the e enlarged view of local electric field distribution over plasmonic nanogaps among Ag nanomushroom arrays. f Comparison of Raman spectra and g corresponding AEFs between Ag layer deposited on bare and Si nanopillar arrays. h Initial repeatability assessment of Raman intensity of R6G collected from 30 random sites of the Ag nanomushroom arrays. i Raman intensity mapping of the Ag nanomushroom arrays. Scale bar: 5 μm. Photographs of the as-prepared flexible microfluidic SERS patch under j bending and k pressing measurements, and l the corresponding intensity variations of Raman signals. The R6G concentrations were 10-8 M in h, i, and l, and all the intensity values were extracted from the characteristic band at ~1364 cm−1. The error bars represent standard deviations from three different samples.
