Flexible plasmonic nanodisk arrays as SERS and biosensing platforms

In this paper, a simple, low-cost, large-scale, and highly sensitive flexible plasmonic nanodisk arrays for surface-enhanced Raman spectroscopy (SERS) and biosensing platforms is proposed. This structure is fabricated by covering a flexible polyethylene terephthalate (PET) substrate with an array of UV nanodisks and then depositing gold (Au) film of a certain thickness. The flexible plasmonic nanodisk arrays exhibit localized plasmonic modes enhanced by local electric fields, rendering them promising for sensing detection. Experimental results show that the characteristic peaks of 4-mercaptobenzoic acid (4-MBA) molecule are clearly distinguishable even at a low concentration of 10^-9 M, with a Raman enhancement factor (EF) value of about 10⁶, which confirms that they have excellent SERS performance. Subsequently, two different resonance dips of the flexible plasmonic nanodisk arrays are observed and analyzed at a non-zero incidence angle. The results demonstrate that the structure has excellent sensing performance in terms of both bulk and surface sensitivity, capable of detecting bovine serum albumin (BSA) biomolecules at ultra-low concentrations of 10^-7 M. Thus, the kind of simple, low-cost, large-scale, and highly sensitive sensing flexible platform has a promising application in various aspects.