T. Ozaki, K. Sugano, T. Tsuchiya, O. Tabata
Department of Micro Engineering, Kyoto University
, Kyoto, JAPAN
ADVISER: Dr .CHENG-SHINE-LIU
REPORTER: SRINIVASU V P & HSIEH,HSIN-YI
STUDENT ID: 9733881 & 9735803
OUTLINE
 Abstract
 Introduction
 Process overview
 Template assisted self assembly
 Results and discussion
 Transfer of nanoparticles
 LSPR characteristics of assembled Nanoparticle
patterns
 Conclusion
Abstract
 Pattern formation
 Dot and line pattern
 Assembled particle pattern transfer
 Localized Surface Plasmon Resonance (LSPR)
Introduction
 Characteristics of nanoparticles
 Conventional nanopatterning techniques
 Advantages of proposed method
 60-nm diameter gold nanoparticles
PROCESS OVERVIEW
1) Self-assembly step
2)Transfer step
Template assisted self assembly
 Mechanism of TASA
 Aqueous particle
dispersion
 Capillary force
Result and discussion
 Effect of cross sectional shape
 Relation between yield and concentration
 The self-assembly yield is defined as the ratio of the
total dot-patterned area to the properly assembled
area.
SEM images of each crosssection before resist
removal. Shape A, B and
Shape C were fabricated by
SF6 and CF4 dry etching,
respectively.
Relation between a crosssectional profile of a
template pattern and a yield of
self-assembly (the concentration
of particle dispersion: 0.002 wt%)
Relation between
concentration of particle
dispersion and a yield of
self-assembly.
Capillary force
Template transfer process
(1) SiO2/Si substrate with assembled particles
(2) Uncured PDMS was poured onto the template
(base compound : curing agent = 10:1)
(3) Degassing for 30 min
(4) Curing PDMS (60 ℃ for 4 hr)
(5) Peel off PDMS
Au self-assemble on the template
(> 90% successful)
Transferred pattern on the PDMS
LSPR principle
 Noble metal nanoparticles exhibit a strong UV-vis absorption band
that is not present in the spectrum of the bulk metal.
 This absorption band results when the incident photon frequency is
resonant with the collective oscillation of the conduction electrons
and is known as the localized surface plasmon resonance (LSPR).








E(λ) = extinction (viz., sum of absorption and scattering)
NA = area density of nanoparticles
a = radius of the metallic nanosphere
em = dielectric constant of the medium surrounding the metallic nanosphere
λ = wavelength of the absorbing radiation
εi = imaginary portion of the metallic nanoparticle's dielectric function
εr = real portion of the metallic nanoparticle's dielectric function
χ = 2 for a sphere (aspect ratio of the nanoparticle)
LSPR characteristics
 These mechanisms are:
 resonant Rayleigh scattering from nanoparticle labels in a manner
analogous to fluorescent dye labels
 nanoparticle aggregation
 charge-transfer interactions at nanoparticle surfaces
 local refractive index changes
• This approach has many advantages including:
– a simple fabrication technique that can be performed in most labs
– real-time biomolecule detection using UV-vis spectroscopy
– a chip-based design that allows for multiplexed analysis
LSPR applications
 Sensor
 adsorption of small molecules
 ligand-receptor binding
 protein adsorption on self-
assembled monolayers
 antibody-antigen binding
 DNA and RNA hybridization
 protein-DNA interactions
LSPR scattering spectrum
Dot pattern
aperture
Schematic of dark-field microscope
line pattern
Dark-field microscope
Scattering spectrums of line patterns
w/o polarization
line pattern w/o polarization
Refractive
index
Vacuum
air
methanol
water
ethanol
hexane
toluene
xylene
1.0
1.0008
1.329
1.330
1.36
1.3749
1.4963
1.498
Spectrum peak vs. refractive index
p-polarized light
s-polarized light
Polarizing cube
beamsplitter
Non-polarized light
non-polarized light
p-polarized light s-polarized light
Conclusions
 Self-assembly nanoparticle pattern formation method can
be realized more than 90% onto 200 x 200 dots.
 Dot and line patterns of gold nanoparticles in diameter
of 60 nm were transferred on a flexible PDMS substrate.
 LSPR sensitivity will be possible by controlling patterns
of the assembled nanoparticles.
 In the future, it is expected that this method will realize
novel MEMS/NEMS devices with nanoparticles patterns on
various 3D microstructures made of various materials via a
carrier substrate.