Roll-to-Roll Development of Surface-Enhanced Raman Scattering Substrates

Because of its high specificity, Raman spectroscopy has proven to be a reliable, field-deployable detection technique for assessing chemical threats such as chemical warfare and biological agents, energetic materials, and illicit narcotics. DOD and DHS utilize various portable Raman systems in sensitive site exploitation, checkpoint scenarios, and for screening potential hazardous content on surfaces or containers. While highly specific, Raman scattering is notoriously low intensity. Surface-enhanced Raman scattering (SERS) potentially overcomes this problem. SERS enhancement occurs when patterned, nanometallic substrates locally amplify electromagnetic plasmonic fields at or near structured surfaces. This results in signal amplification, typically over a million-fold. SERS therefore provides both high specificity and high signal. Currently, however, there is a critical lack of commercially available robust SERS active substrates. MCI has over twenty years of experience in the production of patterned nanostructures on a variety of surfaces and with a variety of metals and oxide coatings. This puts us in a unique position of having a ready-made extensive library of potential SERS substrates which can be manufactured using our proprietary, cost-effective high volume roll-to-roll manufacturing process, thereby enabling a high level of reproducibility. The following tasks will be performed in Phase I to create this robust SERS substrate. Substrates will be chosen from MCI’s extensive nanopattern library based upon the presence of discontinuities as potential “hotspots” and array matrices to provide potential lattice resonance. 1. Test coupons will be created and coated with Au and Ag from these MCI library substrates. 2. Coated coupons will be tested for SERS enhancement and signal-to-noise. 3. Cleaning protocols will be systematically studied to maximize signal-to-noise. 4. Choice of polymer substrate will be systematically studied to maximize signal-to-noise. 5. The application of metal oxide coatings will be examined for both surface protection and SERS enhancement. 6. Further Optimization of candidate substrate design will be performed a plan for Phase II R2R scale-up developed. 7. It is anticipated that at the end of the first five months of Phase I, we will present tested samples of promising candidate substrates to the DOD for their own evaluation and confirmation.