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SEMICONDUCTOR NANOWIRE MANIPULATION USING
IPTOELECTRONIC TWEEZERS
Arsh Jamshidi, Peter J. Pauzauskie, Aaron T. Ohta , Pei-Yu Chiou, Peidong Ya
ng and Ming C, Wu
University of Caligormia, Berkeley,USA
IEEE MEMS2007
報告人 :蘇聖欽
Outline Motivation Theoretical Background
Optical Tweezers Optoelectronic tweezers Theory Optoelectronic tweezers Force Device Structure
Experimental Results Experimental Setup Manipulation of Silicon Nanowires Speed and Trapping Radius Measurements Nanowires Assembly
Conclusion
Motivation
The ability of optical tweezers to perform parallel assembly is hampered by their high optical power density (107w/cm2) and small area (approximately 1 um*1 um) .
Dielectrophoresis can trap nanowires ,but he trapping sites are fixed the electrode pattern .
OET is capable of manipulating a large number of microparticles or cells over a large area .
Outline Motivation Theoretical Background
Optical Tweezers Optoelectronic tweezers Theory Optoelectronic tweezers Force Device Structure
Experimental Results Experimental Setup Manipulation of Silicon Nanowires Speed and Trapping Radius Measurements Nanowire Assembly
Conclusion
Optical Tweezers Mie regime(米氏定理 ) :
適用的粒子大小 diameter of particle >> 。 動量守恆原理。
Rayleigh regime(雷利定理 ) : 適用的粒子大小 diameter of particle << 。 電磁波理論,變動的電場使粒子極化,產生引力。
electric field
particle
Optoelectronic tweezers Theory
They use AC voltage producing electric field .
Arsh Jamshidi,2007
OET
Mechanical
Optical Tweezers Dielectrophoresis
Optical Electrical
Electric field
OET device
Optoelectronic tweezers Force
Optoelectronic tweezers force under an AC bias is given by:
Drag force:
)(Re)6/( 22 EKlrF mDEP
)1)ln(2/(8 lrlvFDrag
η:viscous
V:nanowires velocity
Re(K):depolarization factor
l:nanowirws length
r:nanowires radius
Arsh Jamshidi,2007
Device Structure
OET device apparatus : a top indium-tin–oxide (ITO) electrode a 1–um-thick layer of photoconductive material (amorph
ous silicon) An applied AC bias of 20
Vpp at 50kHz
Arsh Jamshidi,2007
15um ITO
Liquid
1um amorphous silicon
20Vpp
Outline Motivation Theoretical Background
Optical Tweezers Optoelectronic tweezers Theory Optoelectronic tweezers Force Device Structure
Experimental Results Experimental Setup Manipulation of Silicon Nanowires Speed and Trapping Radius Measurements Nanowire Assembly
Conclusion
Experimental Setup
4mW HeNe Laser
Attenuator
40x
OET Device
mirror
Motorizesed stage
20x
CCD Camera
Equipment :
-A 632nm HeNe laser -A 40X objective lens-Solution of DI water and KCl-Olympus BX51M microscopy using a CCD camera
Manipulation of Silicon Nanowires
The long-axis of the nanowires (CdS) aligned with the electric field in the liquid layer .
Si nanowires experienced an attractive force towards the illuminated area after turning on the laser .
Arsh Jamshidi,2007
r:100nm
l:1-5um
Speed and Trapping Radius Measurements
Si nanowires with 390Ω-cm magnitudes comparable to the experimental results .
Figure shows the measured maximum speed of the nanowires versus the applied AC voltage .
Arsh Jamshidi,2007
Max speed:
135um/s
Max radius:
120um
Separation of two nanowires
Nanowires within a trapping radius can still be trapped individually by controlling the scanning speed of the laser spot .
Arsh Jamshidi,2007
r:100nm
l:1-5um
Nanowire Assembly
A spherical lens is used to create a line laser pattern for movement of Si nanowires in arrays of 2 or 3 .
Arsh Jamshidi,2007
Conclusion The flexibility of the optoelectronic tweezers devic
e, low required optical power intensity (optical tweezers power 107w/cm2, OET power 100w/cm2) .
Large working area makes OET a very attractive tool for the manipulation for nanowires (arrays of 2 or 3) .
A maximum velocity of 135um/s and a trapping rad
ius of 122um are achieved using this method .
Reference
[1] Arsh Jamshidi, Peter J. Pauzauskie, Aaron T. Ohta , Pei-Yu Chiou, Peidong Yang and Ming C, Wu, “SEMICONDUCTOR NANOWIRE MANIPULATION USING IPTOELECTRONIC TWEEZERS ”, IEEE MEMS,pp155-158(2007).
[2]Aaron T. Ohta, Pei Yu Chiou, and Min C. Wu, ”Dynamic DMD-Driven Optoelectronic Tweezers for Microscopic Particle Manipulation”, University of California,Los Angeles(2004).
The End