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Instituto Nacional de Astrofísica,
Óptica y Electrónica
Rubén Ramos GarcíaDepartamento de Óptica
[email protected] 52 (222) 266 3100 Ext.2214
Massive manipulation of
microparticles
Overview
Optical Tweezers: Background, Basic Principles and Applications
Massive Manipulation
Time-sharing trapping
Non-Gaussian Beams
Interferometry
Opto-Dielectrophoresis
Plasmons
Photorefractive effect
Concluding remarks
Some History…
P.N. Lebedev (1903) measured the light’spressure!!
Maxwell (1873) shown that light, can in fact,exert pressure
Johannes Kepler (1619) suggested thatcomet’s tails are due to light’s pressure
In 1970, Arthur Ashkin (Bell Labs) demonstrate for the first time the
manipulation of microobject by radiation pressure.
Phys. Rev. Lett. 24, 156 - 159 (1970)
Viking space craft (would've missed Mars by
15,000 km)http://www.planetary.org/programs/projects/solar_sailing/
Consider a micromirror of mass of 10-12 kg
Change of momentum (P=2h/l) in a 100%
reflecting mirror
A stream of photons bombarding
something small can have big effects
Fm = 1000g!!
is the "photon flux," or theNumber of photons/sec in a beam
= P / hn
where P is the beam power.
Force= change of momentumx photon flux ~ 7nN (1 Watt)
PicoNewton Forces
1 picoNewton (pN, 10-12 N) is roughly equal to…
… the gravitational attraction between you and a book
at arm’s length
… the radiation pressure on a penny from a flashlight 1
yard away
… 1 millionth the weight of a grain of salt
Atomic Force Microscope
Optical Tweezers
Force (pN)
1 10 100 1000 10,000
http://yakko.bme.virginia.edu/lab/laserpresent.htm
z
pi
Pf
Dps
pi
pf
Dps
Why light can push objects?Radiation Pressure
Fs
Particles are accelerated along the propagation axis!!
dv dpF ma m
dt dt
Radiation Pressure in Action!!
I. Ricárdez-Vargas, M. Iturbe-Castillo, R. Ramos-García, K. Volke-Sepúlveda, V. Ruíz-Corté
7 February 2005 / Vol. 13, No. 3 / OPTICS EXPRESS 969
Optical Levitation
Partícula
Lente
mg
sF
Partícula
Lente
mg
Foptica
Lente
mg
laser
mg
NASA is exploring ways to use light pressure to propel spacecrafts!
http://science.nasa.gov/science-news/science-at-nasa/2011/24jan_solarsail/
D: 0.59 - 2.68
en agua
m
First Trap: Two-Counter Propagating
Beams
•Long working distance
•Particle guiding
•Works well in fiber traps
How optical trapping works?
Net Force
UP!
Longitudinal Gradient Force
pi
pf
Dp
Transversal Gradient Force
Net Force
Higher intensity!!
pi
pf
pf
Dp
Dp
Potential Well and Force
The potential well depth
can be controlled by
the light intensity
Any object can be trapped
in the potential well!!
Several methods can be implemented to measure the trapping
force.
1
0
0( ) ( ) ( )
x
x
U x F x dx U x
For typical biological application we find that the roll-off frequency well below
1 kHz. In fact, it means that inertial and gravitational forces can be ignored
altogether
Optical Basic Trapping Setup
d << l/20
Particle can be seen as a small dipole induced by
an homogeneous electric field
(Ray optics)
Optical force in the Mie Regime (D>>l):Ray Optics
22 220
0 0 2
0 0
sin 2( ) sin 2( , ) sin 2
2 1 2 cos 2
( , )sin 2 cos .
m t
t
n R RF x y T R
c R R
I x y d d
Where , are the polar and azimuthal angles respectively. T, R are the
transmitance and reflectance averaged over the two orthogonal polarizations
However, in most cases D is comparable to l!!
A Lorentz-Mie model is used, no analytical solution exists and therefore
numerical solutions must be sought.
Single-Molecule Motors
Light-induced Neuron Growth
Ehrlicher et al. PNAS December 10, 2002 vol. 99
no. 25 16027
Neuron PC12 cells (a rat neuron precursor cell line)
stimulated to spread with neuronal growth factor
(5x10-5 mg/ml), and NG108 cells, an immortalized
mouse neuroblastoma rat glioma hybrid cell line.
Cells were cultured in medium at 37°C (PC12:
85% RPMI-1640, 10% horse serum, 5% FBS;
NG108: 90% DMEM, 10% FBS)
Question:
“What if I want more than one
trap?”
Acousto-Optic Deflectors (AODs) can be scanned at hundreds of kHz
Time-share: Repositioning the laser on such a short timescale that the trapped particles experience only a timeaveraged potential.If the optical tweezers are absent for 25 microsecs, the diffusion distance is about 5nm.
From the Physics of Complex Systems Group at the Faculty of Sciences of the Vrije Universiteit, Amsterdam.
Time-share the laser beam:
Holography in Liquid Crystal Modulators
J. E. Curtis, B. A. Koss and D. G. Grier, Optics Communications 207, 169-175 (2002)
Mike MacDonald, Gabe Spalding and Kishan Dholakia, Nature 426, 421 - 424 (2003)
Sorting by a 3D Crystalline Optical Array
Modulated Optical Sieve forOptical Fractionation
)/2exp(2
)(cos
4),( 2
0
22
2
0
0 wrt
L
x
w
PtI
x
r
Optical Forces & Potentials of the Interference Pattern
P. Zemánek, et.al JOSA A 19, 1025 (2002)
Sorting by size
1 and 5 m-diameter latex particles mixture
R1=1 m R2=2.5 m
R3=3 m
Spatial Period LX (m)
Max
imu
m T
ran
sver
se F
orc
e (n
orm
aliz
ed)
There is an optimum
spatial period at LX
~ 2R!!
Sorting by refractive index
1 mm latex (darker)
particles are removed from
the vision field.
Optical Force Optical Potential
latex (n1 1.59)
silica (n2 1.45)
R=2.5 m
L= 2R
Sorting with Computer Generated Holograms
Interferometer. Hard to align and unstable
Not easy to modify (grating period)
SLM. Very stable and dynamical reconfiguration
Manipulation with Plasmons
Kretschmann configuration.
Attenuation distance
~ l/50
Propagation distance
~ 10l
Manipulation using Plasmons
V. Chavez-Garces, Phys. Rev. B 73 085417J. Opt. A: Pure Appl. Opt. 10 (2008) 093001
Brownian motion (named in honor of the botanist Robert Brown) is the random movement
of particles suspended in a liquid or gas
Brownian Motion
Taken from Perrin, Les Atomes,
r=0.53µm
Dt=30 sec
3.2µm
The particle do not move in average!!
Brownian ratchet
No work can be done from systems
in thermal equilibrium!!
Rectifying Brownian Motion
Phys. Rev. Lett. 74, 1504 (1995).
Manuscript in preparation
Dielectrophoresis
http://www.ece.rochester.edu/users/jones/
Electric field gradients can produce forces over dielectric particles!!
Microchips for biological applications
Massively parallel manipulation of single cells and
microparticles using optical images Pei Yu Chiou,
Aaron T. Ohta and Ming C. Wu Nature 436, 370-372 (21
July 2005)
Optical DielectrophoresisUnder illumination
15,000 particle traps are created across a 1.3x 1.0 mm2
Optical Dielectrophoresis
Shih-Mo Yang et. al OPTICS LETTERS Vol. 35, 1959-1961 (2010)
a:Si requires plasma-enhanced chemical vapor deposition, ion
implantation, reactive ion etching, and a nitrogen-filled glove box $$$$$
Optical Organic Dielectrophoresis
Photorefractive materials and their applications I & II, P. Gunter and J-P. Huignard Ed. Springer
Verlag, Berlin, 1988.
Photorefractive Effect
BV
BC
Interference Pattern
Fotoconductividad
Carga Espacial
Campo de
Carga Espacial
Cambio en el Indice de refracción
En Fotorrefractivos:
Patrón de
Interferenci
a
Esc~1.5 kV/cm for diffusion dominated
charge transport
Esc~2-20 kV/cm for photovoltaic
charge transport
1/22
0
2 ' 2
0
2
2 ' 2
0
( )
(1 / ) ( / / )
(1 / ) ( / / )
ph
D q q ph q
sc
D
D q q ph q
E E
E E E E E EE
E
E E E E E E
Xinzheng Zhang, et al 2009 / Vol. 17,
No. 12 / OPTICS EXPRESS 9981
Trapping with evanescent fields: PRE
Charged aluminum particles
Nelson V. Tabiryan et al J. Opt. Soc. Am. B/ Vol. 15,
No. 7/July 1998
2 /( , ) sin(2 / )z
scE x z E e x
Esperamos verlos en el INAOE
como estudiantes de nuestro
postgrado!!
Ibis Ricardez Vargas (UPT Villahermosa)
Ulises Ruiz Corona (Postdoc at Calabria University)
Javier Silva Barranco (PhD student INAOE)
Edy Flores (BUAP)
Kei Fujimura (UDLAP)
Isac Olave Cruz (UDLAP)
Carmelo Rosales (PhD ICFO)
Valeria Rodriguez (PhD ICFO)
Dr. Julio Cesar Ramirez San Juan (INAOE)
Dr. Victor Arrizon (INAOE)
Dra. Karen Volke Sepulveda (IFUNAM)
Coworkers