Sensors
and
Actuators
B
169 (2012) 393–
396
Contents
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at
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Sensors
and
Actuators
B:
Chemical
journa
l
h
o
mepage:
www.elsevier.com/locate/snb
Short
communication
A
novel
refractive
index
detection
method
in
voltage
scanning
surface
plasmon
resonance
system
Kun
Wang
a,b
,
Yuhang
Wan
c
,
Zheng
Zheng
c
,
Fuchu
He
a
,
Zhiyuan
Hu
a,b,∗
,
Jinsong
Zhu
b,∗∗
a
State
key
Laboratory
of
Proteomics,
Beijing
Proteome
Research
Center,
Beijing
Institute
of
Radiation
Medicine,
Beijing
102206,
China
b
National
Center
for
NanoScience
and
Technology,
No.
11
Beiyitiao,
Zhongguancun,
Beijing
100190,
China
c
School
of
Electronic
and
Information
Engineering,
Beihang
University,
37
Xueyuan
Rd.,
Haidian
District,
Beijing
100191,
China
a
r
t
i
c
l
e
i
n
f
o
Article
history:
Received
30
September
2011
Received
in
revised
form
30
November
2011
Accepted
12
December
2011
Available online 21 December 2011
Keywords:
Biosensor
Surface
plasmon
resonance
Voltage
scanning
Electro-optical
effect
a
b
s
t
r
a
c
t
Voltage
scanning
surface
plasmon
resonance
(VSSPR)
detection
is
realized
by
a
metal/electro-optic
dielec-
tric/metal
(MEM)
three-layer
sensor
chip
used
in
a
prism-coupled
attenuated
total
reflection
(ATR)
setup.
Sweeping
DC
voltage
is
applied
and
recorded
in
real
time
with
a
fixed
incident
angle
near
the
reso-
nant
angle.
The
VSSPR
curve
is
defined
by
the
reflected
intensity
and
the
applied
voltage.
It
is
observed
experimentally
that
the
resonant
voltage
obtained
by
the
centroid
method
varied
linearly
with
the
con-
centration
of
the
analytes
and
can
be
used
as
a
characteristic
and
quantitative
parameter
to
describe
the
SPR
effect.
This
method
can
be
used
for
refractive
index
detection,
and
also
have
potential
applications
in
surface
plasmon
resonance
imaging
systems.
© 2011 Elsevier B.V. All rights reserved.
1.
Introduction
As
a
highly
sensitive,
real-time,
and
label-free
sensing
method,
surface
plasmon
resonance
(SPR)
has
found
applications
in
many
research
areas,
such
as
biotechnology,
medical
diagnostics,
drug
discovery,
food
safety,
environmental
monitoring,
and
homeland
security.
A
lot
of
progress
had
been
made
both
in
the
technol-
ogy
and
its
applications
in
the
last
three
decades
[1].
In
the
classic
SPR
systems,
the
angle
[2],
wavelength
[3],
intensity
[4]
or
phase
[5]
of
the
optical
beam
were
exploited
to
characterize
the
bind-
ing
effect
happened
adjacent
to
the
functionalized
metal
layer.
Based
on
these
parameters,
the
SPR
technique
had
been
consid-
ered
as
a
powerful
analytical
tool
to
characterize
quantitatively
the
biochemical
molecule
interactions.
Many
commercial
SPR
devices,
such
as
Biacore
biosensor
series
[6]
and
Corning
Epic
TM
biosen-
sor
[7],
exploited
variations
of
the
resonant
angle
or
the
resonant
wavelength.
However,
with
the
increasing
needs
of
drug
screening
and
measurement
in
complex
biological
systems,
high-throughput,
real-time
analytical
methods
are
in
great
need.
Surface
plasmon
resonance
imaging
(SPRi)
is
realized
based
on
the
intensity
inter-
rogation
method
[8],
where
the
SPR
signal
is
determined
by
the
∗
Corresponding
author
at:
State
key
Laboratory
of
Proteomics,
Beijing
Proteome
Research
Center,
Beijing
Institute
of
Radiation
Medicine,
Beijing
102206,
China.
∗∗
Corresponding
author
at:
National
Center
for
NanoScience
and
Technology,
No.
11
Beiyitiao,
Zhongguancun,
Beijing
100190,
China.
E-mail
addresses:
huzy@nanoctr.cn
(Z.
Hu),
jizhu@nanoctr.cn
(J.
Zhu).
intensity
of
real-time
at
fixed
angle
and
fixed
wavelength
in
the
process
of
the
biochemical
effect.
However,
this
scheme
is
more
vulnerable
to
the
noises
in
the
system,
and
its
resolution
is
worse
than
that
of
the
angular
and
wavelength
interrogation
schemes.
In
order
to
improve
the
resolution
of
the
SPRi,
new
detection
methods
need
to
be
developed.
As
all
know,
classic
angular
or
wavelength
SPR
curve
can
take
advantage
of
the
data
processing
methods,
such
as
the
centroid
method,
to
improve
the
resolution
[9].
If
the
single
point
intensity
detection
in
SPRi
is
replaced
by
a
curve
and
com-
bined
with
the
centroid
method,
the
detection
resolution
may
be
improved.
While
the
performance
of
the
widely
used
single-layer
gold
SPR
sensor
is
already
optimized,
further
improvements
have
been
explored
by
using
multilayer
structure
combining
with
other
physical
effect.
Theoretical
[10]
research
and
some
experiments
[11–13]
on
multilayer
structure
combined
with
the
EO
effect
have
been
carried
out.
2.
Experimental
In
the
article,
a
novel
voltage
scanning
surface
plasmon
resonance
(VSSPR)
system
is
explored.
A
three-layer,
metal/electro-
optic
dielectric/metal
(MEM)
sensor
structure
is
used.
Measure-
ments
are
made
in
a
Kretschmann
configurational
prism-coupled
attenuated
total
reflection
(ATR)
setup
while
the
voltage
is
scanned.
MEM
sandwich
devices
have
been
proven
to
offer
several
unique
advantages:
sharper
resonance
spectrum,
and
better
signal-to-
noise-ratio
(SNR)
than
that
of
the
conventional
single-layer
gold
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see
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matter ©
2011 Elsevier B.V. All rights reserved.
doi:10.1016/j.snb.2011.12.030