Engineering metallic nanostructures for surface plasmon resonance sensing.

Abstract

A change in almost any characteristic of a given material can be detected by one or more beams of light. Optical sensors are extremely sensitive, non-destructive, and immune to electromagnetic interference, offering many significant advantages. Being able to harness this enormous potential within the realm of nanotechnology, however, requires manipulation and control of an optical field on scales well below its wavelength. Dielectric structures cannot achieve this due to diffraction. However, metallic nanos- tructures which support evanescent surface plasmon resonances can provide a solution. Thin gold or silver films, when patterned with nanometer-scale holes, grooves or bumps can efficiently capture incident light and launch an oscillatory motion of the electrons at the film surface, known as a surface plasmon. Using state of the art nanofabri- cation techniques, we have engineered these plasmonic structures to exhibit unusual optical properties not found in natural materials. Such novel materials are broadly ap- plicable and useful, in particular, for sensing. In this dissertation, patterned metallic nanostructures are used to demonstrate high-resolution sensing of complex biomolecu- lar interactions in a quantitative and high-throughput manner. Additionally, efficient chemical sensing via surface enhanced Raman spectroscopy, and proximity sensing with structures suitable for scanning probe microscopy are also presented. The structures are rigorously analyzed with theoretical computer simulations based on finite-difference time-domain methods. Using a newly developed high-throughput fabrication method based on template stripping of patterned metals, this work may open up avenues for the realization of practical plasmonic devices in a wide variety of disciplines.