Review of surface plasmon resonance and localized surface plasmon resonance sensor
Yong CHEN
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Hai MING
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Corresponding author: Hai MING
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University of Science and Technology of China
, Hefei, Anhui, 230026,
China
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Department of Optics & Optical Engineering, Anhui Key Laboratory of Optoelectronic Science and Technology
An overview of recent researches of surface plasmon resonance (SPR) sensing technology in Laboratory of Science and Technology of Micro-Nano Optics (LMNO), University of Science and Technology of China, is presented. Some novel SPR sensors, such as sensors based on metallic grating, metal-insulator-metal (MIM) nanoring and optical fiber, are designed or fabricated and tested. The sensor based on localized surface plasmon resonance (LSPR) of metallic nanoparticles is also be summarized. Because of the coupling of propagating surface plasmons and localized surface plasmons, the localized electromagnetic field is extremely enhanced, which is applied to surface-enhanced Raman scattering (SERS) and fluorenscence enhancement. Future prospects of SPR and/or LSPR sensing developments and applications are also discussed.
1. Introduction
Since the first application of surface plasmon
resonance (SPR) phenomenon for gas detection and
biologic sensor in 1982 [1], the SPR sensing
technology has been widely used for the detection of
biological and chemical analytes, environmental
monitoring and medical diagnostics [25] in the past
two decades.
Surface plasmons (SPs) are coherent oscillations
of free electrons at the boundaries between metal
and dielectric which are often categorized into two
classes: propagating surface plasmons (PSPs) and
localized surface plasmons (LSPs) [6]. PSPs can be
excited on the metallic films which have several
approaches as the Kretschman [7] and Otto [8]
prism coupler, optical waveguides coupler [9],
diffraction gratings [10], and optical fiber coupler
[11], whereas LSPs can be excited on metallic
nano-particles, which both can induce a strong
enhancement of electromagnetic filed in the
near-field region (resonance amplification), leading
to a extensive application in surface-enhanced
Raman scattering (SERS) [12], fluorescence
enhancement [13], refractive index (RI)
measurement [14], biomolecular interaction
detection [15], and so on.
In this paper, we will review some recent works
on SPR (based on PSPs) and localized surface
plasmon resonance (LSPR) (based on LSPs) sensors
at the Laboratory of Science and Technology of
Micro-Nano Optics (LMNO) and make a prospect
on the research and applications of SPR and LSPR
sensors.
2. Current research activities on SPR and LSPR sensors at LMNO
Our research works are focused on new-style
SPR sensors, bimetallic sensor chip for
Kretschmann configuration, optical fiber SPR
sensors and LSPR sensors on SERS and
fluorescence enhancement.
2.1 Novel-style SPR sensors
Two types of SPR sensors with different styles
are designed: metallic grating SPR sensor [16] and
racetrack resonator SPR sensor [17]. Metallic
grating SPR sensor has a high sensitivity for gas
detection, and racetrack resonator SPR sensor has a
broad linear detection range of analyte RI and high
extinction ratio.
2.1.1 Metallic grating SPR sensor
We designed a highly sensitive grating-based
SPR sensor for the gas detection [16]. The sensor
has a high sensitivity at larger resonant incident
angle if negative diffraction order of metallic grating
is used to excite the surface plasmons, as shows in
Fig. 1.
Detector Light source
where m is the permittivity of the metal, res is the
resonant angle of incidence, na is the RI of analyte,
m is an integer representing the diffraction order,
and sign + and sign - correspond to m0 and
m0, respectively.
The sensitivity (dres/dn) of the resonant angle of
0 20 40 60 80 100
Angle of incidence, (degree)
Fig. 3 Reflectance spectra of rectangle-grating-based SPR
sensors with different analyte refractive indices [18].
The sensitivity of the metallic-grating-based
SPR sensor can be improved by using double-dips
method [18]. As shown in Fig. 3, when the RI of the
grating-based SPR sensors depends on the resonant
incident angle (Fig. 2). The sensitivity of the
negative diffraction order(m0) is tens of times
higher than that of positive diffraction order (m0)
at large resonant angle, which is also much higher
than that of conventional prism-based SPR sensor.
For hydrogen detection, a thin Pd film is deposited
on the metallic grating. When the Pd-coated gold
grating is exposed to hydrogen with different
concentrations, the permittivity of Pd layer will
change. Then the change in the resonant angle can
be detected. The theoretical resolution of hydrogen
concentration of the order of 0.001% is obtained
according to our design.
0 0 10 20 30 40 50 60 70 80 90
Resonant angle (degree)
Fig. 2 Sensitivity of the resonant angle of grating-based SPR
sensors versus the resonant angle of incidence (=850 nm,
na=1.02) [16].
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