title: SERS-enhanced piezoplasmonic graphene composite for biological and structural strain mapping.
abstract: Thin-film optical strain sensors have the ability to map small deformations with spatial and temporal resolution and do not require electrical interrogation. This paper describes the use of graphene decorated with metallic nanoislands for sensing of tensile deformations of less than 0.04% with a resolution of less than 0.002%. 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. Since the graphene-nanoisland films are both conductive and optically active, they permit simultaneous electrical stimulation of myoblast cells and optical detection of the strains produced by the cellular contractions.
authors.affiliation: Department of NanoEngineering, University of California, San Diego, 9500 Gilman Drive, Mail Code 0448, La Jolla, CA 92093-0448, USA. dlipomi@eng.ucsd.edu.
authors.forename: Brandon C
authors.initials: BC
authors.lastname: Marin
authors.affiliation: Department of NanoEngineering, University of California, San Diego, 9500 Gilman Drive, Mail Code 0448, La Jolla, CA 92093-0448, USA. dlipomi@eng.ucsd.edu.
authors.forename: Justin
authors.initials: J
authors.lastname: Liu
authors.affiliation: Department of NanoEngineering, University of California, San Diego, 9500 Gilman Drive, Mail Code 0448, La Jolla, CA 92093-0448, USA. dlipomi@eng.ucsd.edu.
authors.forename: Eden
authors.initials: E
authors.lastname: Aklile
authors.affiliation: Department of NanoEngineering, University of California, San Diego, 9500 Gilman Drive, Mail Code 0448, La Jolla, CA 92093-0448, USA. dlipomi@eng.ucsd.edu.
authors.forename: Armando D
authors.initials: AD
authors.lastname: Urbina
authors.affiliation: Department of NanoEngineering, University of California, San Diego, 9500 Gilman Drive, Mail Code 0448, La Jolla, CA 92093-0448, USA. dlipomi@eng.ucsd.edu.
authors.forename: Andrew S-C
authors.initials: AS
authors.lastname: Chiang
authors.affiliation: Department of NanoEngineering, University of California, San Diego, 9500 Gilman Drive, Mail Code 0448, La Jolla, CA 92093-0448, USA. dlipomi@eng.ucsd.edu.
authors.forename: Natalie
authors.initials: N
authors.lastname: Lawrence
authors.affiliation: Department of NanoEngineering, University of California, San Diego, 9500 Gilman Drive, Mail Code 0448, La Jolla, CA 92093-0448, USA. dlipomi@eng.ucsd.edu.
authors.forename: Shaochen
authors.initials: S
authors.lastname: Chen
authors.affiliation: Department of NanoEngineering, University of California, San Diego, 9500 Gilman Drive, Mail Code 0448, La Jolla, CA 92093-0448, USA. dlipomi@eng.ucsd.edu.
authors.forename: Darren J
authors.identifier: http://orcid.org/0000-0002-5808-7765
authors.initials: DJ
authors.lastname: Lipomi