Mar 17, 2008
Surface enhanced Raman scattering on long-range ordered noble-metal nanostructured arrays
Surface enhanced Raman scattering (SERS) has been proven to be a sensitive technique capable of single molecule detection. Moreover, due to its chemical specificity and label-free nature, it attracts increasing attention in analytical, biomedical, environmental, as well as global and homeland security applications. Extremely high SERS enhancement factors (1014) have been achieved at “hot spots” generated at certain narrow gaps between metallic nanostructures and in particular metal colloids. However, the lack of control and reproducibility in the hot-spot generation on metal colloids often limits their practical applications. Consequently, it becomes essential to design and fabricate nanostructured SERS substrates in order not only to generate large local electromagnetic fields but also to tune their surface plasma resonances in a more reproducible way.
To address this challenge, a fast, simple, stable and affordable fabrication method of SERS-active substrates is required. A research group at the Industrial Materials Institute, National Research Council (IMI-NRC) of Canada developed a general procedure to design and fabricate SERS active substrates in a more affordable way based on a nanoimprint lithography method. By using this technique as well as numerical near-field simulations, several types of SERS substrates were optimized, fabricated and used to detect the presence of either strong or weak scattering molecules, as well as photo-chemically sensitive molecules. Moreover, these rapidly fabricated nanostructured SERS active substrates can be successfully used to detect either labeled or label-free DNA molecules.
These recent developments are paving the way toward the development of low-cost SERS substrates integrated with plastic-based lab-on-chip systems for large-scale diagnostic devices.
About the author
Kebin Li is a research officer with IMI-NRC, Canada. He is currently working on the fabrication and characterization of nanostructured materials and devices, and their applications for molecular sensing. Teodor Veres is a senior research officer and Functional Nanomaterials group leader at IMI-NRC. His current research interests are related to the development of functional nanostructures for diagnostics and molecular sensing. This article is co-authored by Liviu Clime, whose current research interest is in modeling plasmonic behavior in various nanostructures. Bo Cui’s current research interest is in nanofabrication and its application in plasmonic devices.