Enhancing Surface Plasmon Resonance Detection Using Nanostructured Au Chips.

Ivan Indutnyi,Marianne Vandenbossche,Mariia Lukaniuk,Dirk Hegemann,Yuriy Ushenin,Roman Khrystosenko,Petro Shepeliavyi,Victor Myn’Ko,Andrii Korchovyi

doi:10.1186/s11671-016-1760-7

Abstract

The increase of the sensitivity of surface plasmon resonance (SPR) refractometers was studied experimentally by forming a periodic relief in the form of a grating with submicron period on the surface of the Au-coated chip. Periodic reliefs of different depths and spatial frequency were formed on the Au film surface using interference lithography and vacuum chalcogenide photoresists. Spatial frequencies of the grating were selected close to the conditions of Bragg reflection of plasmons for the working wavelength of the SPR refractometer and the used environment (solution of glycerol in water). It was found that the degree of refractometer sensitivity enhancement and the value of the interval of environment refractive index variation, Δn, in which this enhancement is observed, depend on the depth of the grating relief. By increasing the depth of relief from 13.5 ± 2 nm to 21.0 ± 2 nm, Δn decreased from 0.009 to 0.0031, whereas sensitivity increased from 110 deg./RIU (refractive index unit) for a standard chip up to 264 and 484 deg./RIU for the nanostructured chips, respectively. Finally, it was shown that the working range of the sensor can be adjusted to the refractive index of the studied environment by changing the spatial frequency of the grating, by modification of the chip surface or by rotation of the chip.

Highlights

Surface plasmon resonance (SPR) systems have found wide use in recent years in sensing applications due to their advantage of high sensitivity, label-free, real-time, and rapid detection
A recent theoretical study [15, 16] has shown that by formation of a sinusoidal profile grating at the surface of the metal layer of the surface plasmon resonance (SPR) sensor used in the Kretschmann configuration, the biosensor sensitivity may be enhanced when compared with an uncorrugated metal surface
We have demonstrated experimentally the possibility to increase the sensitivity of a SPR sensor that operates in the Kretschmann configuration through the formation of a periodic surface relief on the Au chip [17]

Summary

Introduction

Surface plasmon resonance (SPR) systems have found wide use in recent years in sensing applications due to their advantage of high sensitivity, label-free, real-time, and rapid detection. Most of the SPR sensors make use of the attenuated total reflection method (Kretschmann configuration) [6] to excite the surface plasmon wave. Such devices typically show refractive index sensitivities for typical angular interrogation architecture ranging between 50 and 150 deg./RIU (refractive index unit) [7, 8] and refractive index resolutions in the orders of 10−6–10−7 RIU [9]. A recent theoretical study [15, 16] has shown that by formation of a sinusoidal profile grating at the surface of the metal layer of the SPR sensor used in the Kretschmann configuration, the biosensor sensitivity may be enhanced when compared with an uncorrugated metal surface. Surface plasmons propagating in a direction perpendicular to a one-dimensional grating (i.e., along the grating vector)

Methods

Results

Conclusion