Plastic and nonmetallic article shaping or treating: processes – Optical article shaping or treating – Continuous or indefinite length
Reexamination Certificate
1998-06-18
2002-04-23
Vargot, Mathieu D. (Department: 1732)
Plastic and nonmetallic article shaping or treating: processes
Optical article shaping or treating
Continuous or indefinite length
C156S242000, C264S001700, C422S105000
Reexamination Certificate
active
06375871
ABSTRACT:
FIELD OF THE INVENTION
This invention relates to microfluidic articles and methods of manufacturing same.
BACKGROUND OF THE INVENTION
There has been a drive towards reducing the size of instrumentation used for analyzing and otherwise manipulating fluid samples such as biological fluid samples. The reduced size offers several advantages, including the ability to analyze very small samples, increased analytical speed, the ability to use reduced amounts of reagents, and reduced overall cost.
Various devices for microfluid applications have been proposed. These devices typically include a glass or silicon substrate having a lithographically patterned and etched surface provided with one or more structures forming a microfluid processing architecture. Plastic substrates such as polyimides, polyesters, and polycarbonates have been proposed as well.
SUMMARY OF THE INVENTION
There is a need for polymer-based microfluidic articles that can be produced efficiently in commercial-scale quantities, e.g., in the form of a roll good, and that can be selectively tailored to perform a variety of functions, including analytical functions. Accordingly, in a first aspect the invention features a process for preparing a molded article that includes bringing a moldable material and the surface of an open molding tool into line contact with each other to imprint a microfluid processing architecture onto the moldable material. The resulting molded article is then separated from the molding surface of the tool.
A “microfluid processing architecture” refers to one or more fluid-processing structures arranged in a pre-determined, self-contained pattern. Preferably, the architecture includes at least one structure having a dimension no greater than about 1000 micrometers. Moreover, fluid preferably enters and exits the architecture in the z-direction (i.e., the direction perpendicular to the plane of the architecture). For purposes of this invention, examples of suitable microfluid processing architectures include structures selected from the group consisting of microchannels, fluid reservoirs, sample handling regions, and combinations thereof.
An “open molding tool” is a molding tool that lacks a sealed cavity found in closed molds, e.g., of the type used in injection molding.
By “line contact” it is meant that the point at which the tool contacts the moldable material is defined by a line that moves relative to both the tool and the moldable material.
In one embodiment, the moldable material is an embossable polymeric substrate. The microfluid processing architecture pattern is embossed onto the surface of the polymeric substrate to create the molded article.
In another embodiment, the moldable material is a flowable resin composition. One example of such a composition is a curable resin composition, in which case the process includes exposing the composition to thermal or actinic radiation prior to separating the molded article from the molding surface to cure the composition. As used herein, “cure” and “curable resin composition” include crosslinking an already-polymerized resin, as well as polymerizing a monomeric or oligomeric composition, the product of which is not necessarily a crosslinked thermoset resin. An example of a preferred curable resin composition is a photopolymerizable composition which is cured by exposing the composition to actinic radiation while in contact with the molding surface.
Another example of a flowable resin composition is a molten thermoplastic composition which is cooled while in contact with the molding surface to solidify it.
There are two preferred molding processes in the case where the moldable material is a flowable resin composition. According to one preferred process, the flowable resin composition is introduced onto a major surface of a polymeric substrate, and the substrate and molding tool are moved relative to each other to bring the tool and flowable resin composition into line contact with each other. The net result is a two-layer structure in which a microfluid processing architecture-bearing layer is integrally bonded to the polymeric substrate.
A second preferred molding process where the moldable material is a flowable resin composition involves introducing the flowable resin composition onto the molding surface of the molding tool. A separate polymeric substrate may be combined with the flowable resin composition to create a two-layer structure in which a microfluid processing architecture-bearing substrate is integrally bonded to the polymeric substrate.
A substrate may be bonded to the molded article to form a cover layer overlying the microfluid processing architecture. Preferably, the substrate is a polymeric substrate. The molded article may also be provided with one or more microelectronic elements, microoptical elements, and/or micromechanical elements. These microelements may be incorporated in a variety of ways, illustrating the flexibility of the overall process. For example, where the moldable material is an embossable polymeric substrate, that substrate may include the microelements. Where the moldable material is a flowable resin composition and the process involves combining the resin composition with a polymeric substrate during molding, that polymeric substrate may include the microelements. It is also possible to include the microelements in the cover layer. The microelements may also be provided in the form of a separate substrate (preferably a polymeric substrate) that is bonded to the molded article.
The process is preferably designed to operate as a continuous process. Accordingly, moldable material is continuously introduced into a molding zone defined by the molding tool, and the molding tool is continuously brought into line contact with the moldable material to create a plurality of microfluid processing architectures. Preferably, the continuous process yields the article in the form of a roll that includes a plurality of microfluid processing architectures. The roll can be used as is or can be divided subsequently into multiple individual devices. Additional polymeric substrates can be continuously bonded to the article. Examples include cover layers and layers bearing microelectronic, microoptical, and/or micromechanical elements.
In a second aspect, the invention features an article that includes (A) a first non-elastic, polymeric substrate having a first major surface that includes a microfluid processing architecture (as defined above), and a second major surface; and (B) a second polymeric substrate that is integrally bonded to the second major surface of the first substrate. The second substrate is capable of forming a free-standing substrate in the absence of the first substrate. It provides mechanical support for the first substrate and also provides a means for incorporating additional features into the article such as microelectronic, microoptical, and/or micromechanical elements, thereby providing design flexibility.
A “non-elastic” material is a material having insufficient elasticity in the z-direction (i.e., the direction normal to the plane of the substrate) to act as a pump or valve when subjected to a cyclically varying force in the z-direction.
“Integrally bonded” means that the two substrates are bonded directly to each other, as opposed to being bonded through an intermediate material such as an adhesive.
The article preferably includes a cover layer overlying the microfluid processing architecture. The cover layer, which may be bonded to the first surface of the first substrate, preferably is a polymeric layer.
The article preferably includes one or more microelectronic, microoptical, and/or micromechanical elements. The microelements may be included in the first substrate, the second substrate, a polymeric cover layer, or a combination thereof.
In a third aspect, the invention features an article in the form of a roll that includes a first polymeric substrate having a first major surface that includes a plurality of discrete microfluid processing architectures (as defined above), and a second major su
Bentsen James G.
Biernath Rolf W.
Johnston Raymond P.
Poirier Richard J.
3M Innovative Properties Company
Busse Paul W.
Gram Christopher D.
Rogers James A.
Vargot Mathieu D.
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