Optical Tweezers(광집게)의
원리와 응용
Optical tweezers?
두 빔에 의한 포획 광학 부상 (optical levitation)
광 섬 유
빛의 산란에 의한 힘
중력
대물렌즈
Optical tweezers(광집게)
History and Issues
1970, Ashikin : Optical levitation
1986, Ashikin et al : Optical tweezers
1990, Burns et al : Periodic structures by using interference patterns
1997, Chiou et al : Trapping and manipulation of micro particles by using interference fringes
…
<Issues>
- Optical force model
- Manipulation(patterning) of multi-particles
- Bio-Medical applications
1. Optical force models
Optical tweezers
Electromagnetic model
Ray Optics model
- For R <<10
- For R >>10
1) Electromagnetic model
The change in the electrostatic energy ;
1
2
dV t
r dV
W T
V V
2 1 ( 2 1 )( E 2 E 1 ) ( 2 2 1 ) E 1 2 ( , )
1 1
V 1
1 0 2 2 2 2 2 2 2 2
2 exp 2
) 2 2 (
)
(
w z w
y x
w r P
c E r n
I
dV r c I
n n n
V
1
) ) (
(
1
2 1 2
2
0
W F
2 0 2
2
2 2 2
0 2
1
2 1 2
2
0 sinh
exp 2 2
) (
4
w R z a w
R a z
w R erf a
c n
P n
F ax n c c c
0 2 2 2 2 2 0
1 2 1 2
2
0 sinh
exp 2 2
2 )
( 4
w R a
w R a w
R erf a
w R erf a
c n
P n
F tr n c c c c
2) Ray optics model
scattering force
gradient force
A B
F
beam axis
1 4 2 3
y x
z
O O
r
P
RP
TRP
T
2RP
F
AF
sF
gF
AF
BS
c Q P F n
1 collimated beam F g < F s
focused beam F g > F s
Generally, optical trapping force
F g : gradient force F s : scattering force
- Optical force
(1) Axial trapping
dP c q
g n dF
dP c q
s n dF
g g
s s
1 1
ˆ ˆ ,
where,
2 2
1 2
1 2
1
2 2
1 2
1 2
1
2 cos 2
1
] 2 sin )
( 2 2 [sin
cos
2 , cos 2
1
] 2 cos )
( 2 2 [cos
cos 1
R R
R R T
q
R R
R R T
q
g s
g s
net d F d F
F
d
00
2 0 2 2
2 0 0
) sin cos
)(
/ 2 2 exp(
4
g s
ax d dr r r w q q
Q
ax
s g
ax
c Q P n
q q
w r
r dr c d
P F n
1
0
2 0 2 2
2 0 0
1
0) sin cos
)(
/ 2 2 exp(
4
- Axial trapping efficiency
- Axial trapping force
(2) Transverse trapping
IdS q
c q
dF net n 1 ( g sin s cos )
tr
s g
c Q P n
q q
r r
dr c d
P F n
1
0 0
2 0 2
2 0 1
) sin
cos (
) /
2 4 0 exp(
Experimental setup
Laser diode
Objctive lens
lens
PBS
lens1 lens2
CCD
Dichroic mirror
Hallogen lamp
Z-axis
Y-axis Motorized translation
stage
Trapping Image according to trapping direction
Axial trapping
transverse
trapping
논의점 - 광포획 효율의 변화 (포획 깊이)
Laser diode
Lens 1 Lens 2
Dichroic mirror
chamber Cover glass
Slide glass Index matching oil R
(aperture size)
Beam radius
stage
Objctive lens
논의점 - 광포획 효율의 변화 (빔반경)
1.0 1.2 1.4 1.6 1.8 2.0 2.2 2.4 2.6
0.005 0.010 0.015
0.11 0.12 0.13 0.14 0.15 0.16 0.17
Q
ratio (
0
/ R)
For small particle
For big particle
3) Beam optics model
2 0 2
0
2 0 2
0 1
z
r
2 0 2
0
2 0 2 2
0 2
0
2 0 2
0
1 1
z r z
z r
2 R
0 2
0
2 0 2
0
z z r
z
The calculation for existing model was performed the fixed incident angle for all particle. That is, incident angle independent of particle diameter.
2 0 2
0
2 0 2 2
0 2
0
2 0 2
0
2 0 2
0
2 0 2
0
1 1 1
z r z
z r
z r ArcSin
ArcSin R
Incident angle
2. Manipulation(patterning) of multi-particles
CNT
SWNT
( single-walled cabon nanotube)
MWNT
(Mulit-walled cabon nanotube)
1) Carbon nanotubes
CNT trap실험 장치도
Lens 1
Laser diode Dichroic
mirror
Lens 2
Cover glass Slide glass Index matching oil
Objctive lensCCD
Hallogen lamp
PC
5m
HY letters
X
Y
5m
X,Y letters
CCD image of aligned CNT SEM Image of ring pattern
시간에 따른 CNT Ring Pattern 형성
00:03
00:10
22:30
00:05
01:30 00:07
00:00
Laser On 5m
Laser Off
Sequential CCD image of CNT to form ring pattern in the chamber
- OPTICAL TWEEZERS: MICROBUBBLES AND NANOTUBES Dr. Phil Jones , 6 March 2007
- Nanofabrication with Holographic Optical Tweezers
Pamela Korda, Gabriel C. Spalding, Eric R. Dufresne, David G. Grier November 16, 2000
- Single-particle microelectrophoresis with optical tweezers Van Heiningen, Hill, 2007
2) Micro-patterning
Surface tension-enhanced optical trapping for lateral close-packing
Cell-to-cell interactions
Cell fusion dynamics
1) Raman spectroscopy
Rayleigh Scattering
Raman Scattering
E
3. Bio-Medical applications
0
0
0
Rayleigh Stokes Anti-Stoke
m
0 m
0
Schematic Diagram of Experimental Set-up
objective lens CCD camera
chamber dichroic
mirror
beam- splitter
LD
monochromater
PC
PMT
grating dichroic
mirror
source : 0 = 834 nm
The McCreery Research Group
(The Ohio State spectrum)
LTRS system 상용 Raman microscopy
5 m
LTRS system 상용 Raman microscopy
m
2
포획 깊이에 따른 Raman peak 크기 변화
(1) (2)
2) Yeast trap and manipulation
PC Laser
CCD
OL
L L
M M
M
M
L : Lens M : Mirror
BS : Beam Splitter OL : Objective lens
BS Michelson
interferometer
광 포획된 yeast의 발아
발아 하고 있는 yeast
발아하고 있는 yeast의 딸세포에 대한 주위 세포들의 영향
Yeast의 딸세포의 발아.
(a) Living yeast cells (b)Dead yeast cells Changan Xie
et. al
. Optics Letters 27, 4, 2002Tying a knot in the protein actin. By using optical tweezers
to manipulate the ends of the molecule, the chain is curl.
.)3) Biological applications
Calibration of optical trapping efficiency Dependence of the optical trapping efficiency of a biconcave red blood cell flowing in a rectangular microchannel on the sphericity index and the channel geometry
Applicational example) Malaria-infected RBC
Combined microchannel-type erythrocyte (RGB) deformabilitytest with optical tweezers
Cell damage during femtosecond optical trapping
Damagethresholds for biological cells(RBC) Platelet(혈소판)
RBC-under threshold
RBC-above threshold
6 mW 20 mW
Laser power : 90% of the damage threshold (1.8 mW)
t=0 t=7m 30s
t=13m 5s t=20m
t=30m
damage scar
Cell disruption
