Surface-enhanced Raman scattering (SERS) is considered
as the most promising trace detection method since its first
discovery on rough silver electrodes in 1974. After years of
development, it has exhibited great potential as a nondamaging
single molecule analysis method applied in a wide range
of areas, including biological labeling, chemistry, agriculture,[
4] environmental science, food safety, and so forth.
The origin of the SERS effect is still in dispute but there is an
agreement on an electromagnetic enhancement mechanism
(EM) due to the excitation of the localized surface plasmon
resonance (LSPR) on the nanostructures with existance of
nanogaps. Enhancement efficiency and applicability are the
two factors that evaluate the SERS substrate. The effeciency
means the substrate can trace molecules sensitively, reproducibly,
and precisely, while the applicability indicates the SERS
substrate can be prepared easily at low cost.