Fabrication of photopolymer hierarchical micronanostructures by coupling electrospinning and photolithography for SERS substrates

Reported here is the fabrication of photopolymer hierarchical micronanostructures through a combinative process of electrospinning and subsequent photolithography. Electrospun SU-8 (epoxy-based negative photoresist) nanofiber films have been patterned into gratings with periods of 100, 200, 300, and 400 μm, respectively. Deposition of a silver nanolayer on these interlaced nanofiber films would lead to the formation of various plasmonic nanostructures, and therefore, giving rise to abundant surface-enhanced Raman scattering (SERS) "hot spots". In the detection of Rhodamine 6G (R6G), probing molecule, the resultant SERS substrates show both high sensitivity and good reproducibility. The SERS enhancement factor could reach as high as ∼10⁸, indicating high efficiency. The fabrication of patterned, highly efficient SERS substrates may hold a great promise for the integration of SERS substrates in various microdevices such as microfluidic chips.