Wafer-Scale LSPR Substrate: Oblique Deposition of Gold on a Patterned Sapphire Substrate

Label-free detection of biomolecules using localized surface plasmon resonance (LSPR) substrates is a highly attractive method for point-of-care (POC) testing. One of the remaining challenges to developing LSPR-based POC devices is to fabricate the LSPR substrates with large-scale, reproducible, and high-throughput. Herein, a fabrication strategy for wafer-scale LSPR substrates is demonstrated using reproducible, high-throughput techniques, such as nanoimprint lithography, wet-etching, and thin film deposition. A transparent sapphire wafer, on which SiO₂-nanodot hard masks were formed via nanoimprint lithography, was anisotropically etched by a mixed solution of H₂SO₄ and H₃PO₄, resulting in a patterned sapphire substrate (PSS). An LSPR substrate was finally fabricated by oblique deposition of Au onto the PSS, which was then applied to label-free detection of the binding events of biomolecules. To the best of our knowledge, this paper is the first report on the application of the PSS used as an LSPR template by obliquely depositing a metal.