Chemical apparatus and process disinfecting – deodorizing – preser – Control element responsive to a sensed operating condition
Reexamination Certificate
2000-05-25
2003-11-11
Warden, Jill (Department: 1743)
Chemical apparatus and process disinfecting, deodorizing, preser
Control element responsive to a sensed operating condition
C422S068100, C422S105000, C422S105000, C422S105000, C137S827000, C137S833000, C264S259000, C436S180000
Reexamination Certificate
active
06645432
ABSTRACT:
FIELD OF INVENTION
The present invention involves microfluidic network structures, methods for fabricating microfluidic network structures, and methods for using such structures.
BACKGROUND OF THE INVENTION
The need for complexity in microfluidic systems is increasing rapidly as sophisticated functions—chemical reactions and analyses, bioassays, high-throughput screens, and sensors—are being integrated into single microfluidic devices. Complex systems of channels require more complex connectivity than can be generated in conventional two-dimensional microfluidic systems having a single level of channels, since such typical single-level designs do not allow two channels to cross without fluidically connecting. Most methods for fabricating microfluidic channels are based on photolithographic procedures, and yield such two-dimensional systems. There are a number of more specialized procedures, such as stereolithography (see for example, K. Ikuta, K. Hirowatari, T. Ogata,
Proc. IEEE MEMS
'94, Oiso, Japan, Jan. 25-28, 1994, pp. 1-6), laser-chemical three-dimensional writing (see for example, T. M. Bloomstein, D. J. Ehrlich,
J Vac. Sci. Technol. B
, Vol. 10, pp. 2671-2674, 1992), and modular assembly (see for example, C. Gonzalez, R. L. Smith, D. G. Howitt, S. D. Collins,
Sens. Actuators A
, Vol. 66, pp. 315-332, 1998), that yield three-dimensional structures, but these methods are typically time consuming, difficult to perform, and expensive, and are thus not well suited for either prototyping or manufacturing, and are also not capable of making certain types of structures. Better methods for generating complex three-dimensional microfluidic systems are needed to accelerate the development of microfluidic technology. The present invention, in some embodiments, provides such improved methods for generating complex three-dimensional microfluidic systems.
It is known to use a stamp or mold to transfer patterns to a surface of a substrate, (see for example, R. S. Kane, S. Takayama, E. Ostuni, D. E. Ingber, G. M. Whitesides,
Biomaterials
, Vol. 20, pp. 2363-2376, 1999; and Y. Xia, G. M. Whitesides,
Angew. Chem. Int. Ed. Engl
., Vol. 37, pp. 551-575, 1998; U.S. Pat. No. 5,512,131; International Pat. Publication No. WO 97/33737, published Sep. 18, 1997). Most conventional soft lithographic techniques, for example, microcontact printing (&mgr;CP) (see for example, C. S. Chen, M. Mrksich, S. Huang, G. M. Whitesides, D. E. Ingber,
Science
, Vol. 276, pp. 1425-1428, 1997; A. Bernard, E. Delamarche, H. Schmid, B. Michel, H. R. Bosshard, H. Biebuyck,
Langmuir
, Vol. 14, pp. 2225-2229, 1998) and micromolding in capillaries (MIMIC) (see for example, N. L. Jeon, I. S. Choi, B. Xu, G. M. Whitesides,
Adv. Mat
., Vol. 11, pp. 946-949, 1999; E. Delamarche, A. Bernard, H. Schmid, B Michel, H. Biebuyck,
Science
, Vol. 276, pp. 779-781, 1997; E. Delamarche, A. Bernard, H. Schmid, A. Bietsch, B. Michel, h. Biebuyck,
J. Am. Chem. Soc
., Vol. 120, pp. 500-508, 1998; A. Folch, A. Ayon, O. Hurtado, M. A. Schmidt, M. Toner, J.
Biomech. Eng
., Vol. 121, pp. 28-34, 1999; A. Folch, M. Toner,
Biotech. Prog
., Vol. 14, pp. 388-392, 1998), have been limited to procedures that pattern one substance at a time, or to relatively simple, continuous patterns. These constraints are both topological and practical. The surface of a stamp in &mgr;CP, or of a channel system in MIMIC, is effectively a two-dimensional structure. In &mgr;CP, this two-dimensionality of the stamp limits the types of patterns that can be transferred to those comprising a single “color” of ink in the absence of a way of selectively “inking” different regions of the stamp with different materials. Patterning of multiple “inks” using conventional methods requires multiple steps of registration and stamping. In MIMIC, the two-dimensional channel system limits patterning to relatively simple, continuous structures or requires multiple patterning steps.
There remains a general need in the art for improved methods for forming patterns on surfaces with soft lithographic techniques, and for providing techniques able to pattern onto a surface arbitrary two-dimensional patterns and able to form complex patterns comprised of multiple regions, where different regions of the pattern can comprise different materials, on a surface without the need for multiple steps of registration or stamping and without the need to selectively “ink” different regions of the stamp with different materials. The present invention, in some embodiments, provides such improved methods for forming patterns on surfaces with soft lithographic techniques.
SUMMARY OF THE INVENTION
The present invention involves, in certain embodiments, improved microfluidic systems and procedures for fabricating improved microfluidic systems, which contain one or more levels of microfluidic channels. The inventive methods can provide a convenient route to topologically complex and improved microfluidic systems. The present invention also, in some embodiments, involves microfluidic systems and methods for fabricating complex patterns of materials, such as biological materials and cells, on surfaces. In such embodiments, the invention involves microfluidic surface patterning systems and methods for fabricating complex, discontinuous patterns on surfaces that can incorporate or deposit multiple materials onto a surface. The present invention, in some embodiments, can provide improved stamps for microcontact surface patterning able to pattern onto a surface arbitrary two-dimensional patterns and able to pattern multiple substances onto a surface without the need for multiple steps of registration or stamping during patterning and without the need to selectively “ink” different regions of the stamp with different materials.
According to one embodiment of the invention, a microfluidic network is disclosed. The microfluidic network comprises a polymeric structure including therein at least a first and a second non-fluidically interconnected fluid flow paths. At least the first flow path comprises a series of interconnected channels within the polymeric structure. The series of interconnected channels includes at least one first channel disposed within a first level of the structure, at least one second channel disposed within a second level of the structure, and at least one connecting channel fluidically interconnecting the first channel and the second channel. At least one channel within the structure has a cross-sectional dimension not exceeding about 500 &mgr;m. The structure includes at least one channel disposed within the first level of the structure that is non-parallel to at least one channel disposed within the second level of the structure.
In another embodiment of the invention, a microfluidic network is disclosed. The microfluidic network comprises an elastomeric structure including therein at least one fluid flow path. The flow path comprises a series of interconnected channels within the structure. The series of interconnected channels includes at least one first channel disposed within a first level of the structure, at least one second channel disposed within a second level of the structure, and at least one connecting channel fluidically interconnecting the first channel and the second channel. At least one channel within the structure has a cross-sectional dimension not exceeding about 500 &mgr;m, and the structure includes at least one channel disposed within the first level of the structure that is non-parallel to at least one channel disposed within the second level of the structure.
In yet another embodiment, a polymeric membrane is disclosed. The polymeric membrane comprises a first surface including at least one channel disposed therein, a second surface including at least one channel disposed therein, and a polymeric region intermediate the first surface and the second surface. The intermediate region includes at least one connecting channel therethrough fluidically interconnecting the channel disposed in the first surface and the channel disposed in the second surface o
Anderson Janelle R.
Cherniavskaya Oksana
Chiu Daniel T.
Jackman Rebecca J.
McDonald Cooper
President & Fellows of Harvard College
Sines Brian J.
Warden Jill
Wolf Greenfield & Sacks P.C.
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