JAEA-Review-2010-065.pdf:15.99MB - 日本原子力研究開発機構

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Fabrication of Dielectrophoretic Devices Using
Poly-dimethylsiloxane Microstructures
by Proton Beam Writing
Y. Shiine a) , H. Nishikawa a) , Y. Furuta a) , T. Satoh b) , Y. Ishii b) , T. Kamiya b) ,
R. Nakao c) and S. Uchida c)
a) Department of Electrical Engineering, Shibaura Institute of Technology,
b) Department of Advanced Radiation Technology, TARRI, JAEA,
c) Department of Electrical and Electronic Engineering, Tokyo Metropolitan University
Proton Beam Writing (PBW) is a direct write process
1), 2)
using focused beam of MeV protons . The focused MeV
proton beam has several advantages over other techniques
using sources such as electrons, x-rays, and UV light.
When the high-aspect ratio microstructures such as pillar
arrays produced by PBW were applied to dielectrophoretic
(DEP) devices, it was previously demonstrated that a
spatially modulated electric field can serve as an efficient
trapping sites for microbes such as Escherichia coli
(E.coli) 3) . Since the PBW is serial and a relatively slow
lithographic process, it is time consuming to expose large
area of resists for the whole device including micro fluidic
channels with a length of several tens of millimeters. Such
a drawback can be overcome by a coupled use of soft
lithography techniques 4) with a master produced by PBW on
poly-dimethylsiloxane (PDMS). In this paper, we
demonstrate the fabrication of prototypes of 3D-DEP
devices equipped with high-aspect-ratio pillars, which were
combined with micro fluidic channels produced by a
replication SU-8 master.
High-aspect-ratio pillar arrays with area of 60 × 1000 m2
were fabricated by PBW with a 13-m thick SU-8 on a
SU-8 layer on
silica or silicon
Pour PDMS over the
master
Development
(a) PBW.
Pillar arrays
SU-8 master
PDMS peeled off
from the master
(b) Soft lithography of micro fluidic channel by a
SU-8 master.
Sealed pillar
Cross section image
(c) Sealing pillar arrays on silica with PDMS.
Fig. 1 Fabrication processes of a DEP device by (a)
proton beam writing of SU-8 for pillar arrays and a
master, coupled with (b) a soft lithography using
SU-8 master on PDMS, followed by (c) sealing the
pillar arrays on silica with PDMS.
JAEA-Review 2010-065
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silica substrate. A master for a PDMS micro fluidic
channel was fabricated by PBW on SU-8 layer on a silicon
substrate. The PBW was performed at 1.0-1.7 MeV proton
beam focused around 1 m, using a dedicated PB writer at
the Center for Flexible Micromachining, Shibaura Institute
of Technology, or at the Takasaki Ion Accelerators for
Advanced Radiation Application (TIARA), Japan Atomic
Energy Agency.
Figure 1 shows a process flow of fabricating DEP
devices, including (a) PBW of SU-8 layer, (b) soft
lithography of micro fluidic channel, and (c) sealing the
pillar arrays with the PDMS, where the silica substrate with
pillar arrays is sealed with PDMS with a micro fluidic
channel. Figure 2 (a) show an optical microscope image of
the pillar arrays on silica, which were successfully sealed
with a PDMS micro fluidic channel. Figure 2 (b) shows a
photograph the DEP device with tubing at inlet and outlet
ports.
A soft lithography technique with PDMS was
successfully applied to the fabrication of the 3D-DEP device
equipped with high-aspect-ratio pillar arrays. By the
coupled use of the soft lithography technique with PBW, the
fast prototyping capability of the PBW was highlighted for
the development of the 3D-DEP devices.
References
1) F. Watt et al., Materials Today 10, 6 (2007) 20-29.
2) Y. Furuta et al., J. Vac. Sci. Tech. B. 25 (2007)
2171-2174.
3) Y. Furuta et al., Microelectron. Eng. 86 (2009)
1396-1400.
4) J. C. McDonald and G. M. Whitesides, Acc. Chem. Res.
35 (2002) 491-499.
Pillar arrays
Micro fluidic
channel
200 μm
(a) Optical microscope image
of pillar arrays on silica.
Access port
1mm
(b) Photograph of
the sealed device.
Fig. 2 (a) Optical microscope image of a sealed pillar
arrays on silica and (b) photograph DEP device.