The prospect of ultrasensitive, rapid, and cost-effective molecular analysis has been one of the main drivers behind the rapidly evolving field of plasmonics. I will illustrate this development by describing several recent molecular sensing and actuation experiments that are all based on the extremely efficient conversion of light from the far-field to or from the near-field by virtue of plasmon excitation in metal nanostructures. The examples utilize different kinds of molecular contrast (fluorescence, Raman scattering, refractive index, viscosity) as well as plasmon-enhanced thermal and optical forces for diverse applications, including controlled DNA release, detection of nerve gases, and studies of molecular interactions at the single molecule limit.
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