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Slide1
About OMICS Group
OMICS Group International is an amalgamation of
Open Access publications
and worldwide international science conferences and events. Established in the year 2007 with the sole aim of making the information on Sciences and technology ‘Open Access’, OMICS Group publishes 400 online open access
scholarly journals
in all aspects of Science, Engineering, Management and Technology journals. OMICS Group has been instrumental in taking the knowledge on Science & technology to the doorsteps of ordinary men and women. Research Scholars, Students, Libraries, Educational Institutions, Research centers and the industry are main stakeholders that benefitted greatly from this knowledge dissemination. OMICS Group also organizes 300
International conferences
annually across the globe, where knowledge transfer takes place through debates, round table discussions, poster presentations, workshops, symposia and exhibitions
.Slide2
About OMICS Group Conferences
OMICS Group International is a pioneer and leading science event organizer, which publishes around 400 open access journals and conducts over 300 Medical, Clinical, Engineering, Life Sciences,
Pharma
scientific conferences all over the globe annually with the support of more than 1000 scientific associations and 30,000 editorial board members and 3.5 million followers to its credit.
OMICS Group has organized 500 conferences, workshops and national symposiums across the major cities including San Francisco, Las Vegas, San Antonio, Omaha, Orlando, Raleigh, Santa Clara, Chicago, Philadelphia, Baltimore, United Kingdom, Valencia, Dubai, Beijing, Hyderabad,
Bengaluru
and Mumbai.Slide3
Keynote
:
Molecular
Sensing Based on Optical Whispering-Gallery Mode Microsensors
Zhixiong “James” Guo
3
rd
Internation
a
l
Conferenc
e
and
Exhib
i
tion
o
n
Biosenso
r
s
&
Bioelectronics
August
11
-
13,
2014,
Sa
n
Antonio,
Taxes
,
USASlide4
Rutgers Jersey
Root
s
,
Global ReachChartered in 1766, Rutgers has a unique history
as a colonial college, a land-grant institution
,
and a state university. In 1864, Rutgers prevailed over another major college in NJ to become the state’s land-grant college.
T
he Birthplace of College Football
With
more
than
65,000
student
s
on
campuses
in
Camden,
Newark
,
and
New
Brunswic
k
,
Rutgers
is
one
of
the
nation’s
major
public institutions
of
higher
education.Slide5
Major
Campu
s
– New Brunswick/PiscatawayLand: 2,688 acresStudents: > 50,000
< 40 miles to Times Square,
NYCSlide6
Presentation Outline
Intro
d
uct
i
onWhat is whispering-
gallery mode?Lab fabrication of optical
WGM
devices Molecular sensing based on optical WGMPhysical and Mathematical DescriptionWGM senso
r in
a micro-opto-electro-fluidic system (MOEFS) Governing equations
---- Charg
e
an
d
fluid
tran
s
port
----
Dynamics of adsorption and desorption---- Maxwell’s equations
Results and Discussion
Validation with experimental measurement Influence of applied electrical potential Dynamics of adsorptionInfluence of resonance modes Sensor curves
Concl
udi
n
g
remarksSlide7
Whispering Gallery
Whis
p
er
i
ng gallery at St. Paul’s Cathedral Simul
ation of the whispering gallery at St. Paul’s
C
a
thedralThe study of acoustic whispering gallery began in St. Paul’s Cathedral,LondonLord Rayleigh was the first to describe how sound waves
were
reflected around the walls of the gallery due to
its
circu
la
r
shape
i
n
1878
The
term 'whispering gallery' has been borrowed in the physical sciences to descr
ibe other forms of whispering-gal
lery waves such as light
Images from WikipediaSlide8
Optical Whispering Galleries
Sound
wave
s
have a wavelength on order of meters. Light,
on the other hand, has a wave
l
engt
h on the order of microns or lessOptical whispering-gallery mode (WGM) occurs in small dielectric circular shapes
such
as spheres, rings, or cylinders, with diameters on the micrometer
scale
Optical
WGM
resona
tors
ar
e
c
haracter
ized as having extremely high Quality factors (Q- factors) and very small mode
volumesSuch features them ideal for
micro/nano photonic devices, such a
s lasers, filters, sensors, and quantum systemsDistinct researchers include Stephen Arnold at NYU-Poly, Kerry Vahala at Caltech, Russi
a
n
scientist
V
.S.
Ilchenko, French scientist Serge Haroche (Nobel Laureate in Physics, 2012), etc.
Whis
p
ering gallery mode resonators
Im
a
ge
s
fro
m
Vaha
la 2
0
0
3
,
Natur
e
4
2
4Slide9
Fabrication of Microbeads &
Tapers
Im
a
ges from Ma, Rossmann
& Guo, 2008,J. Phys. DSlide10
Generation of
Optical
WGM
WGM occurs when light, confin
ed by total internal reflect
i
on
s, orbits near the surface of a dielectric medium of circular
geometr
y and returns in phase after each
revol
u
t
ion.
Th
e
elec
t
r
omagnetic
field can close on itself, giving
rise to resonance.
f / f
r / r n / nTypical resonance spectrumSensing Principle:Slide11
Example: Sensing of A
Sin
g
le
Nano-Entity0.5Single Nano
Particle1.0
0
-0.5
-1.0
W
aveguide
H
.
Quan
&
Z.
Guo
,
Nanotechnolog
y, 2007; or Haiyong Quang, Ph.D. Dissertation, Rutgers University, 2006.
Cavity of 2 µm in diameter
In contact400 nmSlide12
• Science 10
August
2
007: Vol. 317 no. 5839 pp. 783-787Received
for publication 11 May 2007Label
-Fre
e
, Single-Molecule Detection with Optical Microcavities(Dr. Zhixiong Guo proposed such a similar ideal back in
early
2005, See below)NSF Proposal Number: CTS-0541585
. Starting
Date
:
Augus
t
15
,
2005
Princi
pal Investigator: Guo, ZhixiongProposal Title: SGER: Single
Molecule-Radiation Interaction in Whisperin
g GalleryMode Evane
scent Field• Nanotechnology 18 (2007) 375702 (5pp)Received 9 May 2007. Published 22 August 2007
Sim
u
lat
i
on
of
single transparent molecule interaction with an optical microcavit
y.
Haiyong Quan
and Zhixiong GuoResults fromHaiyong
Qua
n
,
Ph.D.
Dis
s
ert
a
ti
o
n
,
Rutger
s
University
,
M
a
y
2006
Chara
c
terization
of Optical Whispering Gallery Mode Resonance and Applications• Nature Methods - 5, 591 - 596 (2008)Whispering-gallery-mode biosensing: label-free detection down to single molecules. Frank Vollmer & Stephen Arnold
Earlier
Literature
on
Sin
g
le
Molecule
DetectionSlide13
• Appl.
Phys.
Le
t
t. 80, 4057 (2002)Protein detection by optica
l shift of a resonant microcavity.
F.
Vollmer, D. Braun, A. Libchaber, M. Khoshsima, I. Teraoka, S. Arnold.Optics Letters, Vol. 28, Issue
4,
pp. 272-274 (2003)Shift of whispering-gallery modes in
microsphere
s
by
prot
e
in
ad
s
orption.
S
. Arnold, M. Khoshsima, I. Teraoka, S. Holler, and F.
VollmerSelected Topics
in Quantum Electronics,
IEEE J, vol.12 (1) , 2006Polymer microring resonators for biochemical sensing applicationsC.Y. Chao, W.
Fu
n
g
,
L
.
J. GuoAdvanced Functional Materials, vol. 15 (11),
pp. 1851
-1859,
2005Macroporous Silicon Microcavities for M
acrom
ol
ecul
e
Dete
c
tion
H.
Ouyan
g
,
M.
Christo
p
he
rse
n
,
R.
Vi
a
r
d
,
B. L. Miller and P. M. Fauchet• JQSRT, vol. 93 (1-3), pp. 231–243, 2005Simulation of whispering-gallery-mode resonance shifts for optical miniature biosensorsH. Quan and Z. Guoand many othersEarlier Literature on Layered DetectionSlide14
Proposed MOEFS with a
WGM
Sensor
Anode
/Gound
Analyt
e
inlet portBuffer
inlet port
Outlet portChannel
Gap
Optical
waveguide
Inciden
t
l
ight
T
otal
internal
r
efle
c
tion
d
ө
WGM
sensor
Charge
d
analyte
flow
di
r
ection
l
h
w
Chan
n
el
Enlarged
simulatio
n
r
egion
G
r
ound/Anod
eSlide15
Adsorption and Sensing
of
Smal
l MoleculesMolecules/AnalytesMethod
II: Filtration and trapping of analytes
in
porous layerLei and Guo 2012, Nanotech.Method I: Surface attachment of analytes Lei and Guo 201
1, Biomic
rofluidicsMolecular monolayerSlide16
Governing Equations
Cha
r
ge transporta
t
ion equationsfor the charged analyte, h
ydroxide ion and hydrogen ion.
Lang
m
uir model for adsorptionPoisson equation for electrical potentialE F (c
i z
i )iNavier-Stokes equation
with porous
medium
model
D
2
C
i
,ci i i i i ,d i
K V C
(z w FC
) Ki 1, 2,3iiCt2
E
f
P
2
E
V
V
V
V
t1( C ) K CCsads sdes st
C
K
Slide17
Governing Equations (cont.)
T
im
e
-dependent
Maxwell’s equations
E ; E H
H 0; H J E
t
t
where
1 2
H 2 H 0 1 2 E
2
E
0cc cr0
j
c i
2
c
j=1,2
indicate
the ele
c
trical
condu
c
tivity
of
b
ulk
sol
ution
and
mic
r
o resonator, respectively .In-plane TE wavesE(x, y,t) E (x, y)e eitz zH (x, y,t) [H
(
x
,
y
)
e
H
(
x
,
y
)
e
]
e
i
t
x x y ySlide18
T
i
m
e
(
s
)
R
e
l
a
t
i
v
e
c
o
v
e
r
a
g
e
(
C
s
/
)
0
0
2
0
0
40
0
60
0
0
.
2
0
.
4
0
.
6
0
.
8
U
n
a
ff
e
c
t
E
x
p
e
ri
m
e
n
t
S
i
m
u
l
a
t
i
o
n
2
0
p
M
50
0
p
M
Valid
a
tion
wit
h
Ex
p
eriment
Sampl
e analyt
e
: Bovine
Seru
m
Alb
u
min
(BSA)
proteins that
carry neg
a
tive
cha
r
g
e
s at neutral
pH
O
n
a hy
d
rophilic
surfa
c
e, the ele
c
trostatic
attraction
b
e
tween oppo
sitel
y
cha
r
g
e
d
mat
e
rial
is often the major driving
force for a
d
sor
p
tion
of bio
molecules. In a
S
i
3
N
4
/
H
2
O
solutio
n
,
the
SiN
H
+
sp
e
cies re
m
ains the
c
h
a
r
g
e
d
3
one.
Langm
u
ir
approach
is adopted
to des
c
ribe
the protein ad
sorptio
n proc
e
ss.
The
k
e
y
ass
u
mptions are:
(a) only a mo
n
ola
y
er
for
m
s
by
ad
sor
p
tion;
(b) the ad
sor
b
ing
sur
face is comp
o
se
d
of discrete,
identic
a
l,
and
no
n
-interacting
sites
;
(c) the ad
sor
p
tion
proce
s
s for each
molecule is
ind
e
p
e
ndent;
and
(d) there is no
molecul
e
-molecule interactions
sin
ce the
c
oncentration
is v
e
ry
lo
w
.
Ads
o
rption
of
BSA
at t
w
o
di
f
ferent concentrations
onto
a
si
lica
m
icro
resonator
at p
H
6.6
in
the
absence
of
e
xternal
ele
c
tric
a
l
field
(experi
m
ental
results
by
Y
eung
et
al
.
2009,
Colloids and
s
urfa
c
es
B:
Biointerfac
e
s
)Slide19
Results: Detection of BSA
Pro
t
eins
1
0
0
0
0
1
50
0
0
T
i
m
e
(
s
)
F
r
e
qu
e
n
c
y
do
w
n
s
h
i
f
t
(
M
H
z
)
50
0
0
2
0
4
0
6
0
8
0
L
a
ng
m
u
i
r
f
i
t
t
i
n
g
1
6
.
7
V
/
c
m
50
p
M
2
3
.
3
V
/
c
m
10
p
M
T
ime
trace
of
optic
a
l
resonance
frequency
down
shifts
induced
by
B
S
A
adsorption,
showin
g
t
he
Lang
m
uir
adsorp
t
ion
pa
t
tern
2
0
4
0
6
0
C
on
c
e
n
t
r
a
t
i
o
n
(
p
M
)
F
r
e
qu
e
n
c
y
do
w
n
s
h
i
f
t
(
M
H
z
)
0
8
0
0
5
0
10
0
15
0
20
0
25
0
30
0
40
0
35
0
23
.3
V
/
c
m
16
.7
V
/
c
m
6
.
6
7
V
/
c
m
The
resonance
frequency
shift
s
versus
the
bu
l
k BSA
concen
t
rati
on
for
di
f
ferent
appl
i
ed
voltage
gradien
t
s
at
ste
ady
s
ta
t
eSlide20
Results: Aminoglycoside Adsorption
in
Porous
LayerContour of analyte concentr
ation in the porous resonator
a
nd
the equipotential lines of the electrical potential field for the case with 10 pM feed and 17.7
V/cm
A grounding electrode is placed inside the resonator t
o at
tra
c
t
the
positi
v
el
y
-cha
r
ged neomycin molecules. The porous vicinity surrounding the electrode is t
he most concentrated region, which jus
tifies the fact that,
the applied electrical potential is a predominant driven mechanism over the convection and diffusion for the charged
analyte tran
sp
o
rt.
Mole
cular
concentration near the resonator can be enhanced by a
magnitude
of
order, that is very useful for extremely low-con
c
entration molecule
d
e
tectio
n
.
Sampl
e
molec
u
les:
Ne
o
my
c
in,
an aminoglyc
o
sid
e
antibiotic,
that
carries positive charges at neutral pHSlide21
Influence of Electrical Potenti
a
l
on
AdsorptionThe aminoglycoside concentration profiles along th
e resonator radial direction with a feed concentration
of 10
pM for various applied voltage gradients.
5
1
0
1
5
2
0
2
5
E
l
e
c
t
ri
c
a
l
p
o
t
e
n
t
i
a
l
g
r
a
d
i
e
n
t
(
V
/
c
m
)
A
v
e
r
a
g
e
d
s
u
r
f
a
c
e
d
e
n
s
i
t
y
(
pg
/
c
m
2
)
0
15
0
10
0
5
0
20
0
25
0
1
0
p
M
5
0
p
M
Influ
ence of ele
c
tric
a
l
potentia
l
on t
h
e
surfa
c
e
densit
y insi
d
e
the
po
r
ous
r
eso
natorSlide22
Time Trace of Adsorpt
i
on
and
Induced WGM ShiftsThe time trace of the adsorbed aminoglycosides on the r
esonator surface for three different oper
ation ca
se
s.The resonance frequency down shifts with Langmuir fitting for two different feeding and appli
ed voltage
conditions under the first-order and second-order modes,
respectively
.Slide23
Mode Profile and Sensor
Curves
D
i
st
a
n
c
e
f
r
o
m
t
h
e
r
e
s
o
n
a
t
o
r
c
e
n
t
e
r
(
m)
N
o
r
m
a
li
z
e
d
e
n
e
r
g
y
C
o
n
c
e
n
t
r
a
t
i
o
n
(
p
M
)
0
3
3
.
5
4
4
.
5
5
5
.
5
1
3
3
.
5
4
4
.
5
5
5
.
5
0
.
2
0
.
4
5
0
0
.
6
0
.
8
3
0
4
0
6
0
7
0
8
0
9
0
1
s
t
o
r
d
e
r
m
o
d
e
2
n
d
o
r
d
e
r
m
od
e
C
on
c
e
nt
r
a
t
i
o
n
Energ
y
d
i
strib
u
tions
in
the
r
esonator
radial
di
r
ection for
t
h
e fi
r
s
t
-
and
se
c
on
d
-o
r
der
modes and
t
h
e
a
mi
n
o
c
onc
e
ntrati
o
n
p
r
ofile in and
outside
the
r
eso
nato
r
for
t
h
e
c
ase
of
17.7
V/c
m applied volt
a
ge
g
r
adient and
10
p
M
fe
e
d
co
ncentr
a
tion.
The
optical
senso
r
curves
at
ste
a
d
y
-
sta
te aminogly
c
oside
deposition.Slide24
Conclusions
A
porou
s
ring microresonator integrated in a
microelectrofluidic system can functi
o
n
as both a filter and an optical whispering-gallery mode sensor.The microelectrofluidi
c
forces augment substantially the filtration capability o
f
the
system,
whic
h
separates
the
target
molecules from its solution and enriches the
analyte deposition inside the
porous resonator.
This alters the optical properties of the resonator and shifts the optical WGM resonance frequency,
l
eadin
g
to
label-free ultrasensitive detection of small molecules
a
t pico
molar concentration levels and below
.
The
second
-orde
r
whisper
i
n
g
-galler
y
mode
si
gna
l
i
s
found
to
giv
e
greater resonance frequency shift than the commonly adopted first-order mode of other types of WGM sensors.For large molecules such as proteins, they are detectable via direct surface attachment due
to
s
urfac
e
modif
i
cation
or
electro
s
tatic
force.Slide25
Acknowledgment
This
material
is based upon work supported by NSF grants CBET-1067141 and CTS-0541585, and
by the US Department of Agriculture under grant number 2008
-
01336.
Former graduate students who made great contributions: Dr. Haiyong QuanDr. Lei HuangDr. Qiulin MaUseful discussion with Dr. Guoying Chen, Rese
arch Chemist,
at Eastern Regional Research Center, USDA Agricultural Research Service, is appreciate
d.
Thank
Y
ou!Slide26
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