Microfilters for collecting micron-size airborne biological agents are designed and fabricated using a micro-electro-mechanical-system (MEMS) fabrication technology. The thickness of the microfilter ranges from 1 μm–3 μm, and the hole diameter from 5 μm–12 μm. Iterations between experimental and numerical studies are carried out to attain efficient microfilter designs with low pressure drop. Two orders of magnitude reduction of viscous power consumption have been achieved. A design rule of the filter in a low Reynolds-number range was first derived from numerical simulations. Highly accurate measurements of the three-dimensional (3-D) geometry, side-wall profile, and diameter of the micron-size holes are critical in validating and modifying the design rule. The effect of the surface slip is found to be small in the tested Knudsen-number range.

Issue Section:
Technical Papers
Keywords:
filters, micromachining, design engineering, power consumption
Topics:
Filters, Pressure drop, Geometry, Micromachining, Particulate matter, Flow (Dynamics), Design, Energy dissipation, Computer simulation
1.
Kittilsland
,
G.
,
Steme
,
G.
, and
Norden
,
B.
,
1990
, “
A Submicron Particle Filter in Silicon
,”
Sens. Actuators A
,
23
, pp.
904
–
907
.
2.
van Rijn, C. J. M., and Elwenspoek, M. C., 1995, “Micro Filtration Membrane Sieve with Silicone Micro Machining for Industrial and Biomedical Application,” Proceedings of IEEE the Eighth Workshop on Micro Electro Mechanical Systems, Amsterdam, the Netherlands, pp. 83–87.
3.
van Rijn
,
C. J. M.
,
van der Wekken
,
M.
,
Hijdam
,
W.
, and
Elwenpoek
,
M. C.
,
1997
, “
Deflection and Maximum Load of Microfiltration Membrane Sieves Made with Silicon Micromachining
,”
J. Microelectromech. Syst.
,
6
, pp.
48
–
54
.
4.
Yang
,
X.
,
Yang
,
J. M.
,
Tai
,
Y.-C.
, and
Ho
,
C.-M.
,
1999
, “
Micromachined Membrane Particle Filters
,”
Sens. Actuators A
,
73
, pp.
184
–
191
.
5.
Chu
,
W.-H.
,
Chin
,
R.
,
Huen
,
T.
, and
Ferrari
,
M.
,
1999
, “
Silicone Membrane Nanofilters from Sacrificial Oxide Removal
,”
J. Microelectromech. Syst.
,
8
, pp.
34
–
42
.
6.
Tu
,
J. K.
,
Huen
,
T.
,
Szema
,
R.
, and
Ferrari
,
M.
,
1999
, “
Filtration of Sub-100 nm Particles Using a Bulk-Micromachined, Direct-Bonded Silicon Filter
,”
Journal of Biomedical Microdevices
,
1
, pp.
113
–
119
.
7.
Ho, C.-M., Huang, P.-H., Yang, J. M., Lee, G.-B., and Tai, Y.-C., 1998, “Active Flow Control by Micro Systems,” FLOWCON, International Union of Theoretical and Applied Mechanics (IUTAM) Symposium of Mechanics of Passive and Active Flow Control, Gottingen, Germany, pp. 18–19.
8.
Wieghardt
,
K. E. G.
,
1953
, “
On the Resistance of Screens
,”
Aeronaut. Q.
,
4
, pp.
186
–
192
.
9.
Derbunovich
,
G. I.
,
Zemskaya
,
A. S.
,
Repik
,
Ye. U.
, and
Sosedko
,
Yu. P.
,
1984
, “
Hydraulic Drag of Perforated Plates
,”
Fluid Mech.-Sov. Res.
,
13
, pp.
111
–
116
.
10.
Sampson
,
R. A.
,
1891
, “
On Stokes’s Current Function
,”
Philos. Trans. R. Soc. London, Ser. A
,
182
, pp.
449
–
518
.
11.
Dagan
,
Z.
,
Weinbaum
,
S.
, and
Pfeffer
,
R.
,
1982
, “
An Infinite Solution for the Creeping Motion Through an Orifice of Finite Length
,”
J. Fluid Mech.
,
115
, pp.
505
–
523
.
12.
Tio
,
K.-K.
, and
Sadhal
,
S. S.
,
1994
, “
Boundary Conditions for Stokes Flows Near a Porous Membrane
,”
Appl. Sci. Res.
,
52
, pp.
1
–
20
.
13.
Hasegawa
,
T.
,
Suganuma
,
M.
, and
Watanabe
,
H.
,
1997
, “
Anomaly of Excess Pressure Drops of the Flow Through Very Small Orifices
,”
Phys. Fluids
,
9
, pp.
1
–
3
.
14.
Ho
,
C.-M.
, and
Tai
,
Y.-C.
,
1998
, “
Micro-Electro-Mechanical Systems (MEMS) and Fluid, Flows
,”
Annu. Rev. Fluid Mech.
,
30
, pp.
579
–
612
.
15.
Harley
,
J. C.
,
Huang
,
Y.
,
Bau
,
H. H.
, and
Zemel
,
J. N.
,
1995
, “
Gas Flow in Micro-Channels
,”
J. Fluid Mech.
,
284
, pp.
257
–
274
.
16.
Ebert
,
W. A.
, and
Sparrow
,
E. M.
,
1965
, “
Slip Flow in Rectangular and Annular Ducts
,”
ASME J. Basic Eng.
,
87
, pp.
1018
–
1024
.
17.
Sreekanth, A. K., 1968, “Slip flow through long circular tubes,” Rarefied Gas Dynamics, Academic Press, pp. 667–680.
18.
Donaldson
,
J. R.
, and
Schnabel
,
R. B.
,
1987
, “
Computational Experience With Confidence Regions and Confidence Intervals for Nonlinear Least Squares
,”
Technometrics
,
29
, pp.
67
–
82
.
19.
Pelka
,
J.
,
Weiss
,
M.
,
Hoppe
,
W.
, and
Mewes
,
D.
,
1989
, “
The Influence of Ion Scattering on Dry Etch Profiles
,”
J. Vac. Sci. Technol. B
,
7
, pp.
1483
–
1487
.
20.
Daubenspeck
,
T. H.
, and
Sukanek
,
P. C.
,
1990
, “
Development of Chlorofluorocarbon/Oxygen Reactive Ion Etching Chemistry for Fine-Line Tungsten Patterning
,”
J. Vac. Sci. Technol. B
,
8
, pp.
586
–
595
.
21.
May
,
P. W.
,
Field
,
D.
, and
Klemperer
,
D. F.
,
1993
, “
Simulation of Sidewall Profiles in Reactive Ion Etching
,”
J. Phys. D: Appl. Phys.
,
26
, pp.
598
–
606
.
Copyright © 2001
 by ASME
You do not currently have access to this content.