Here we demonstrate the microfabrication of deep (>25 μm) polymeric microstructures created by replica-molding polydimethylsiloxane (PDMS) from microfabricated Si substrates. The use of PDMS structures in microfluidics and biological applications is discussed. We investigated the feasibility of two methods for the microfabrication of the Si molds: deep plasma etch of silicon-on-insulator (SOI) wafers and photolithographic patterning of a spin-coated photoplastic layer. Although the SOI wafers can be patterned at higher resolution, we found that the inexpensive photoplastic yields similar replication fidelity. The latter is mostly limited by the mechanical stability of the replicated PDMS structures. As an example, we demonstrate the selective delivery of different cell suspensions to specific locations of a tissue culture substrate resulting in micropatterns of attached cells.

Issue Section:
Special Papers on Microsystems Technology in Medicine and Biology
Topics:
Microfluidics, Molding, Plasma desorption mass spectrometry, Silicon-on-insulator, Microfabrication, Semiconductor wafers, Biological tissues, Etching, Mechanical stability, Particle spin, Plasmas (Ionized gases), Resolution (Optics), Rotation, Spin (Aerodynamics)
1.
Ayon, A. A., et al, 1998, “Etching characteristics and profile control in a time multiplexed inductively coupled plasma etcher,” presented at the Solid State Sensor and Actuator Workshop, Hilton Head, SC.
2.
Bhatia
S. N.
,
Yarmush
M. L.
, and
Toner
M.
,
1997
, “
Controlling cell interactions by micropatterning in co-cultures: hepatocytes and 3T3 fibroblasts
,”
J. Biomed. Mater. Res.
,
34
(
2
):
189
–
199
.
3.
Bloomstein
T. M.
, and
Ehrlich
D. J.
,
1992
, “
Stereo laser micromachining of silicon
,”
Appl. Phys. Lett
,
61
:
708
708
.
4.
Brody
J. P.
,
Han
Y.
,
Austin
R. H.
, and
Bitensky
M.
,
1995
, “
Deformation and flow of red blood cells in a synthetic lattice: evidence for an active cytoskeleton
,”
Biophys. J.
,
68
(
6
):
2224
–
2232
.
5.
Brunette
D. M.
,
1986
, “
Spreading and orientation of epithelial cells on grooved substrata
,”
Exp. Cell Res.
,
167
(
1
):
203
–
217
.
6.
Chaudhury
M. K.
, and
Whitesides
G. M.
,
1991
, “
Direct Measurement of Interfacial Interactions Between Semispherical Lenses and Flat Sheets of Poly(Dimethylsiloxane) and Their Chemical Derivatives
,”
Langmuir
,
7
(
5
):
1013
1013
.
7.
Chaudhury
M. K.
, and
Whitesides
G. M.
,
1992
, “
Correlation Between Surface Free-Energy and Surface Constitution
,”
Science
,
255
(
5049
):
1230
1230
.
8.
Chaudhury
M. K.
,
1993
, “
Surface Free-Energies of Alkylsiloxane Monolayers Supported on Elastomeric Polydimethylsiloxanes
,”
J. Adhes. Sci. Technol
,
7
(
6
):
669
669
.
9.
Chaudhury
M. K.
, and
Owen
M. J.
,
1993
, “
Correlation Between Adhesion Hysteresis and Phase State of Monolayer Films
,”
J. Phys. Chem.
,
97
(
21
):
5722
5722
.
10.
Delamarche
E.
,
Bernard
A.
,
Schmid
H.
,
Michel
B.
, and
Biebuyck
H.
,
1997
, “
Patterned delivery of immunoglobulins to surfaces using microfluidic networks
,”
Science
,
276
(
5313
):
779
–
781
.
11.
Delamarche
E.
,
Schmid
H.
,
Michel
B.
, and
Biebuyck
H.
,
1997
, “
Stability of molded polydimethylsiloxane microstructures
,”
Adv. Mater.
,
9
(
9
):
741
–
746
.
12.
Folch, A., and M. A. Schmidt, 1998, “Wafer-level in-registry microstamping,” J. Microelectromech. Sys., in press.
13.
Folch
A.
, and
Toner
M.
,
1998
, “
Cellular micropatterns on biocompatible materials
,”
Biotechnol Prog.
,
14
(
3
):
388
–
392
.
14.
Guckel, H., et al., 1996, “Advances in photoresist based processing tools for 3-dimensional precision and micro mechanics,” presented at the Solid-State Sensor and Actuator Workshop, Hilton Head, SC.
15.
Hwang
G. S.
, and
Giapis
K. P.
,
1997
, “
On the origin of the notching effect during etching in uniform high density plasmas
,”
J. Vac. Sci. Technol. B
,
15
(
1
):
70
–
87
.
16.
Kapur
R.
,
Spargo
B. J.
,
Chen
M. S.
,
Calvert
J. M.
, and
Rudolph
A. S.
,
1996
, “
Fabrication and selective surface modification of 3-dimensionally textured biomedical polymers from etched silicon substrates
,”
J. Biomed. Mater. Res.
,
33
(
4
):
205
–
216
.
17.
Kim
E.
,
Xia
Y. N.
, and
Whitesides
G. M.
,
1995
, “
Polymer Microstructures Formed by Molding in Capillaries
,”
Nature
,
376
(
6541
):
581
581
.
18.
Kim
E.
,
Xia
Y. N.
, and
Whitesides
G. M.
,
1996
, “
Micromolding in capillaries: Applications in materials science
,”
J. Amer. Chem. Soc.
,
118
(
24
):
5722
5722
.
19.
Kumar
A.
,
Biebuyck
H. A.
, and
Whitesides
G. M.
,
1994
, “
Patterning Self-Assembled Monolayers—Applications in Materials Science
,”
Langmuir
,
10
(
5
):
1498
1498
.
20.
Kumar
A.
, and
Whitesides
G. M.
,
1993
, “
Features of Gold Having Micrometer to Centimeter Dimensions Can Be Formed Through a Combination of Stamping With an Elastomeric Stamp and an Alkanethiol Ink Followed by Chemical Etching
,”
Appl. Phys. Lett.
,
63
(
14
):
2002
2002
.
21.
Larsson, O., et al., 1997, “Silicon based replication technology of 3D-microstructures by conventional CD-injection molding techniques,” presented at Transducers ’97—International Conference on Solid-State Sensors and Actuators, Chicago, IEEE.
22.
Lee
K. Y.
, et al.,
1995
, “
Micromachining applications of a high resolution ultrathick photoresist
,”
J. Vac. Sci. Technol. B
,
13
(
6
):
3012
3012
.
23.
Li
P. C.
, and
Harrison
D. J.
,
1997
, “
Transport, manipulation, and reaction of biological cells on-chip using electrokinetic effects
,”
Anal. Chem.
,
69
(
8
):
1564
–
1568
.
24.
Lorenz
H.
, et al.,
1997
, “
SU-8: a low-cost negative resist for MEMS
,”
J. Micromechanic. Microengineer.
,
7
(
3
):
121
121
.
25.
Martynova
L.
, et al.,
1997
, “
Fabrication of plastic microfluid channels by imprinting methods
,”
Anal. Chem.
,
69
(
23
):
4783
–
9
.
26.
McCormick
R. M.
,
Nelson
R. J.
,
Alonso-Amigo
M. G.
,
Benvegnu
D. J.
, and
Hooper
H. H.
,
1997
, “
MicroChannel electrophoretic separations of DNA in injection-molded plastic substrates
,”
Anal. Chem.
,
69
(
14
):
2626
–
2630
.
27.
Morra
M.
, et al.,
1990
, “
On the aging of oxygen plasma-treated polydimethylsiloxane surfaces
,”
Journal of Colloid and Interface Science
,
137
(
1
):
11
–
24
.
28.
Mullenborn, M., H. Dirac, J. W. Petersen, and S. Bouwstra, 1995, “Fast 3D laser micromachining of silicon for micromechanical and microfluidic applications,” presented at the 8th International Conference on Solid-State Sensors and Actuators, and Eurosensors IX, Stockolm, Sweden.
29.
Petersen
K. E.
,
1982
, “
Silicon as a mechanical material
,”
Proc. IEEE
,
70
(
5
):
420
–
457
.
30.
Potter, M. C., and J. F. Foss, 1982, Fluid Mechanics, Michigan, Great Lakes Press.
31.
Ratner, B. D., A. S. Hoffman, F. J. Schoen, and J. E. Lemons, 1996, Biomaterials Science: an Introduction to Materials in Medicine, San Diego, Academic Press.
32.
Ristic, L., ed., 1994, Sensor Technology and Devices, Boston, MA, Artech House.
33.
Srinivasan
R.
, et al.,
1997
, “
Micromachined reactors for catalytic partial oxidation reactions
,”
AIChE J.
,
43
(
11
):
3059
3059
.
34.
Woolley
A. T.
, and
Mathies
R. A.
,
1994
, “
Ultra-high-speed DNA fragment separations using microfabricated capillary array electrophoresis chips
,”
Proc. Natl. Acad. Sci. USA
,
91
(
24
):
11348
–
11352
.
This content is only available via PDF.
Copyright © 1999
 by The American Society of Mechanical Engineers
You do not currently have access to this content.