SERS-enhanced piezoplasmonic graphene composite for biological and structural strain mapping.

Brandon C Marin,Shaochen Chen,Darren J Lipomi,Andrew S-C Chiang,Justin Liu,Natalie Lawrence,Armando D Urbina,Eden Aklile

doi:10.1039/c6nr09005b

Brandon C Marin, Shaochen Chen + Show 6 more

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https://doi.org/10.1039/c6nr09005b

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Journal: Nanoscale	Publication Date: Jan 1, 2017
Citations: 15	License type: cc-by

Affiliation: University of California, San Diego

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.

Highlights

Piezoresistive sensors undergo a reversible change in resistance with mechanical strain and are ubiquitous in microelectromechanical systems (MEMS), wearable sensors, and structural health monitors.[1,2,3]
The transmission electron microscope (TEM) images for gold (Fig. 2a) and silver (Fig. 2b) nanoislands suspended on single-layer graphene show small gaps between the nanostructures, which appear as lighter regions
In analogy to the gauge factor (GF) used for piezoresistive sensors to quantify the response to strain,[4] we propose a plasmonic gauge factor (GFplasmonic), which quantifies the surface-enhanced Raman scattering (SERS) response of films of metallic nanoparticles to strain, Iunstrained À Istrained

Summary

Introduction

Piezoresistive sensors undergo a reversible change in resistance with mechanical strain and are ubiquitous in microelectromechanical systems (MEMS), wearable sensors, and structural health monitors.[1,2,3] Most conductive objects exhibit increased electrical resistance (R) along a strained axis because stretching increases the length and reduces the cross sectional area normal to the strain. Optical modes of sensing provide a route of interrogation that is in principal orthogonal to electrophysiological signals, and can

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