SERS-enhanced piezoplasmonic graphene composite for biological and structural strain mapping.Thin-film optical strain sensors have the ability to map small deformations with spatial and temporal resolution and do not require electrical interrogation.  The nanoisland-graphene composite films contain gaps between the nanoislands, which when functionalized with benzenethiolate behave as hot spots for surface-enhanced Raman scattering (SERS).  Mechanical strain increases the sizes of the gaps; this increase attenuates the electric field, and thus attenuates the SERS signal.  This compounded, SERS-enhanced "piezoplasmonic" effect can be quantified using a plasmonic gauge factor, and is among the most sensitive mechanical sensors of any type. 
SERS
The nanoisland-graphene composite films contain gaps between the nanoislands, which when functionalized with benzenethiolate behave as hot spots for surface-enhanced Raman scattering (SERS). 
Raman scattering