  The ability to perform sensitive, real-time, in situ, multiplex chemical
analysis is indispensable for diverse applications such as human health
monitoring, food safety testing, forensic analysis, environmental sensing, and
homeland security. Surface-enhanced Raman spectroscopy (SERS) is an effective
tool to offer the ability by virtue of its high sensitivity and rapid
label-free signal detection as well as the availability of portable Raman
spectrometers. Unfortunately, the practical utility of SERS is limited because
it generally requires sample collection and preparation, namely, collecting a
sample from an object of interest and placing the sample on top of a SERS
substrate to perform a SERS measurement. In fact, not all analytes can satisfy
this requirement because the sample collection and preparation process may be
undesirable, laborious, difficult, dangerous, costly, or time-consuming. Here
we introduce "Place & Play SERS" based on an ultrathin, flexible, stretchable,
adhesive, biointegratable gold-deposited polyvinyl alcohol (PVA) nanomesh
substrate that enables placing the substrate on top of an object of interest
and performing a SERS measurement of the object by epi-excitation without the
need for touching, destroying, and sampling it. Specifically, we characterized
the sensitivity of the gold/PVA nanomesh substrate in the Place & Play SERS
measurement scheme and then used the scheme to conduct SERS measurements of
both wet and dry objects under nearly real-world conditions. To show the
practical utility of Place & Play SERS, we demonstrated two examples of its
application: food safety testing and forensic analysis. Our results firmly
verified the new measurement scheme of SERS and are expected to extend the
potential of SERS by opening up untapped applications of sensitive, real-time,
in situ multiplex chemical analysis.
